YOGA VERSUS AEROBIC EXERCISE IN MENTAL WELL-BEING

■/V- A Thesis submitted to the faculty of San Francisco State University In partial fulfillment of KiGtT the requirements for • C 3<£ the Degree

Master of Science

In

Kinesiology: Exercise Physiology

by

Katlyn Rae Camper

San Francisco, California

May 2015 Copyright by Katlyn Rae Camper 2015 CERTIFICATION OF APPROVAL

I certify that I have read Yoga Versus Aerobic Exercise in Mental Well-Being by Katlyn

Rae Camper, and that in my opinion this work meets the criteria for approving a thesis

submitted in partial fulfillment of the requirement for the degree (Master of Science in

Kinesiology: Exercise Physiology at San Francisco State University.

Marialice Kern, Ph.D. Professor

Matt Lee, Ph.D. Professor

Professor YOGA VERSUS AEROBIC EXERCISE IN MENTAL WELL-BEING

Katlyn Rae Camper San Francisco, California 2015

Purpose: The purpose of this study was to evaluate and compare yoga and aerobic exercise in its effects of promoting mental well-being in college students. This study will specifically compare mental well-being and autonomic nervous system function in college students enrolled in yoga and aerobic activity type course. Methods: There were a total of 334 participants enrolled in either a yoga or aerobic type activity course. Each student completed a total of five surveys to assess mental well-being. Based off indicated interest 32 individuals were randomly selected to participate in measures to assess heart rate variability, which is an indicator of autonomic function. Results: There were no significant differences found between activity type and better overall mental well-being indicated by the questionnaire. There were also no significant differences found in heart rate variability indices between groups. Conclusion: Individuals who have been participating in physical activity for longer periods of time tend to have lower levels of stress.

certify that the Abstract is a correct representation of the content of this thesis.

C€< mX D • ‘ I fS Thesis Committee:ee \ Date PREFACE AND/OR ACKNOWLEDGEMENTS

This study would not have been accomplished without the constant encouragement and guidance from my amazingly talented group of committee members, Dr. Kern, Dr. Lee, and Dr. Veri. Thank you all for your support over the last couple year. I could not have picked a better group of mentors to direct me through this journey. I would also like to thank the chair of the Kinesiology Department, Dr. Mi-Sook Kim, for helping with the survey statistics portion. I want to thank my research assistant, Chayanne Robinson, for all her hard work and time in helping assist me with data collection. I also must thank my parents who have pushed me to go above and beyond the norms to pursue my lifelong goals and dreams. Lastly, I want to thank the participants that donated their time to help me complete this study, without all of you, none of this would have been possible.

v TABLE OF CONTENTS

List of Tables...... vii

List of Figures...... viii

Introduction...... 1

Stress/Immune System...... 2

Heart Rate Variability/ ANS ...... 10

Depression/Anxiety...... 11

Y oga...... 13

Aerobic Exercise...... 25

Yoga vs. A erobic...... 31

Research Implications...... 34

Methods...... 35

Participants/Inclusion Criteria...... 35

Procedures...... 36

Statistics...... 37

Results...... 38

Survey M easures...... 38

Physiological Measures...... 41

Discussion...... 44

References...... 48 LIST OF TABLES

Table Page

1. Exercise type vs. Survey ...... 38 2. Pearson Correlation vs. Activity Level ...... 39 3. Sex differences vs. Surveys ...... 40 4. Physiological descriptive information ...... 41 5. Heart Rate Variability Indices ...... 42

vii LIST OF FIGURES

Figures Page

1. Exercise type vs. survey ...... 39 2. Sex differences vs. Stress ...... 41 3. High Frequency Power between groups ...... 42 4. Low Frequency Waves between groups ...... 43 5. Total Power between groups ...... 43 6. LF-HF Ratio between groups ...... 44

viii 1

INTRODUCTION

Stress is a constant factor in today’s society that can potentially jeopardize health if left unchecked. The stress and stress-induced disorders are fast growing epidemics of

“modern society” (135). Stress is a response to physical or psychological distress that generates a large number of chemical and hormonal reactions in the body (6). Daily stressors are necessary for the development of a healthy body, they teach the body to adapt to daily challenges; but when a stressor becomes chronic, individuals are unable to control these stressors which can lead to potential disorders such as depression, anxiety, hypertension, Alzheimer’s and Parkinson’s disease, along with many other health issues

(125). It is now widely believed that the cause of many disease conditions is a complex interaction between genetics, behavioral factors, and stress (39). Upon entering into college, students are immersed into a new, challenging, and stressful environment.

Factors that can lead to this are a competitive curriculum, excessive demands on coping abilities within physical, emotional, intellectual, financial, and social terms, along with many other contributing factors that lead to high levels of stress in college students (84).

Apart from periodically and regularly releasing accumulated stress and tension, it is imperative to move towards a life with eustress. Eustress is essential in the brain’s ability to retain all the powers and capabilities obtained by a sharp intellect, vital for day-to-day functioning in a highly competitive and stressful life as a student (84). Yoga and aerobic exercise are two widely known, supported, and accepted holistic approaches for the treatment and prevention of stress (56, 155). Yoga shifts a balance from the sympathetic 2

nervous system, the flight-or-fight response, to the parasympathetic nervous system, relaxation response (155), while aerobic exercise in contrast is a stressor that stimulates the sympathetic nervous system (125). This brings to question which form is more efficient and beneficial in alleviating the stress that can potentially lead to various diseases and disorders. Both utilize opposite systems, yet promote similar effects.

Though there are numerous studies that support both forms separately, there are minimal studies comparing which modality is more favorable for reducing stress. The purpose of this study was to compare the differences between two different forms of physical activity (i.e. yoga and aerobic) in psychological and physiological indicators of mental well-being among college-aged students.

Stress

The term stress is used to encompass a vast number of differentiated emotional states (108). The processing and handling of stress is based off events or circumstances that are not absolute, but relatively set and reset by positive and negative experiences

(34). Subjective judgments or reactions will be a function of the discrepancies of the present stimuli from a neutral point determined by past experiences (34). Psychological stress occurs when an individual perceives environmental demands to exceed their adaptive capacity (32). Stress may be external (environmental), internal (emotions), or a combination of both (84). Elliot and Eisdorfer (1982) used taxonomy to distinguish stressors and placed them into five categories based on two important dimensions: duration and course (49). The five-categories of stressors are acute time-limited stressors, 3

brief naturalistic stressors, stressful event sequences, chronic stressors, and distant

stressors (133). Public speaking is an example of an acute time-limited stressor that

involves a brief situational challenge. Brief naturalistic stressors involve a person

confronting a real life short-term challenge such as an academic examination (49).

Stressful event sequences involve a focal event that gives rise to a series of related

challenges such as a major natural disaster (49). A chronic stressor usually pervades an

individual’s life, forcing one to restructure their identity or social roles; the individual

does not know whether or when the challenge will end (49). A distant stressor forms

because of a traumatic experience that occurred in the past yet still alters their health

because of the long lasting cognitive and emotional stress (49). Although a certain level

of stress is necessary and results in improved performance, too much stress has negative

effects on health (36).

Stress is not unitary, different demands have different physiological effects (128).

Generally, stressful events are thought to influence the pathogenesis of a disease by

causing negative affective states (feelings of anxiety and depression), which in turn exert

a direct effect on the biological processes or behavioral patterns that influence disease risk (1,31). The stress response involves the release of a variety of substances, including neurotransmitters, neurotropic factors, hormones, and cytokines, that allow the body to deal with the challenges of daily life (125). The ability to successfully recover from stressful events in early life leads to the strengthening of synaptic connections in neural networks and a reduction in vulnerability to succeeding stressors (125). On the other 4

hand, exposure to chronic stress can be pathogenic and most likely result in long-term or permanent changes in emotional, physiological, and behavioral responses that influence susceptibility to diseases and/or disorders such as anxiety, depression, hypertension,

Alzheimer’s disease, and Parkinson’s disease (31). The body can succumb rapidly to physical stressors with the exception of chronic, maladaptive stress that has a significant psychological component (6). It is the psychological and social strain that can continue on for years. A growing body of evidence has suggested that long-term psychological stress can alter basic immune processes (29, 77, 108, 111, 152).

Components of the immune system

In order to understand the relationship between psychosocial stressors and the immune system it is important to distinguish between natural and specific immunity. The cells involved in natural immunity are known as all-purpose-cells. They do not provide defense against any particular pathogen but can attack a number of different pathogens and do so in a short amount of time (minute to hours) (133). The specific immunity is characterized by greater precision but less speed. Even though the specific immunity process is efficient in terms of the number of cells that have to be supported on a daily basis, it creates a delay of up to several days before a full defense is mounted, therefore, the body must rely on natural immunity to contain infection during this time (133). The specific immunity in humans is composed of cellular and humoral responses. The cellular immune response is mounted against intracellular pathogens such as viruses and the humoral immune response fights against extracellular pathogens like parasites and 5

bacteria (82). An individual’s effort to manage the demands of stressful experiences may lead them to engage in certain behaviors that can modify or adapt the immune system processes (133).

Effect of acute and chronic stress on immune response

The natural versus specific immune domains affected by stress are consistent with the duration of a stressor (acute vs. chronic). When stressors are acute and time-limited, there is an adaptive redistribution of cells and a preparation of the natural immune system

(6). Acute stress induces natural immunity, which requires little time and energy investment to act against invaders (44). The immune system loses the ability to adapt when a stressor becomes chronic. With an increase in stressor duration, it results in a shift from potentially adaptive changes to potentially detrimental changes. In comparison with natural immunity, the specific immune response is activated with chronic stress. The specific immune system is time and energy intensive, and is only evoked when either a stressor/ infection persists for a long period of time (6). In general, an appropriate stress response is initiated by a stressor, sustained for an appropriate time, and then switched off, allowing for recovery. In contrast, repeated uncontrollable stressors may result in a lack of adaption, prolonged responses with no recovery period, or inadequate responses

(93). Although there is little known about the psychological pathways that link stressors with the immune system; it is thought that cytokine expression represents a promising example of an avenue for research linking stress, immune changes, and disease (133). It has been hypothesized that chronic stress elicits simultaneous enhancement and 6

suppression of the immune response by altering the patterns of cytokine secretion and

down-regulating the cortisol receptors (86). This down-regulation, in turn, reduces the

cells’ capacity to respond to anti-inflammatory signals and allows cytokine-mediated

inflammatory processes to flourish (101). The activation of the pituitary-adrenocortical

system is thought to occur during threats appraised as overwhelming (61). The activation

of this system often accompanies chronic stress, as well as clinical depression (53). It has

been suggested that by being able to proactively handle stress in everyday life it could

alleviate the constant activation of the endocrine system, which in turn, increases the

effectiveness of the immune system (6). Findings have suggested a biphasic model in

which acute stress enhances and chronic stress suppresses the immune response (133).

Adaptive Response to Stress

Stress adaptations provide a theoretical framework for understanding the effects

of exercise training on mental well-being (128). Adaptive responses to stress affect

various body systems such as the autonomic, cardiovascular, gastrointestinal, and

immune systems (95). In parallel with behavioral adaption, stress causes physiological

adaption via the central nervous system. A stressor activates the sympathetic system and

acutely depletes levels of norepinephrine within the brain. Long-term repeated stressors

preserve brain norepinephrine levels allowing the body to adapt to stress in a healthy

manner (18). When stress becomes chronic, synthesis of norepinephrine is increased to preserve brain concentrations (128). Stress also activates the central and peripheral opioid

systems, which accounts for some instances of analgesic (pain-relieving) response caused 7

by stress (58, 144). The opioid mechanisms have been implicated in mood improvements of regular runners (3, 69). The fundamental importance of the opioid response arises from their inhibitory control of the stress response (128).

The general function of the immune system is to identify and eliminate foreign,

“non-self’ material that contact or enter the body (108). The immune system is comprised of a network of glands, nodes, and organs that work together to protect the body from harmful organisms. The system requires a constant supply of energy and nutrients to maintain its optimal function and performance. The effect of stress on the immune system is mediated by a complex network of signals that function in a bidirectional manner with the nervous, endocrine, and immune systems (6). The nervous system to immune system network involves sympathetic fibers descending from the brain into both primary (bone marrow and thymus) and secondary (spleen and lymph nodes) lymphoid tissues (51). The fibers release a variety of substances that influence the immune response by binding to receptors of white blood cells (2, 51, 76). The neuro-endocrine immune system network involves the hypothalamic-pituitary-adrenal axis (HPA), the sympathetic-adrenal- medullary axis (SAM), and the hypothalamic-pituitary-gonadal axis (HPG) (12). The

HPA axis and SAM axis are two of the endocrine response systems that are particularly reactive to psychological stress (31). Maier and Watkins (1998) discovered that immunological changes associated with stress were adapted from immunological change in response to infection, further supporting the relationship between stress and immune function (83). The immunological activation in human’s results in a syndrome called 8

“sickness behavior”, which consists of behavioral changes as well as an increased

responsiveness to pain and depression (83).

HPA axis on immune response

The homeostatic interactions between the hypothalamus, pituitary, and adrenal

glands constitute the HPA axis. The HPA axis controls reactions to stress and regulates

various body processes including digestion, mood, energy use, and the immune system

(6). The hypothalamus synthesizes two pepetides, vasopressin and corticotrophin

releasing hormone (CRH), that regulate the anterior lobe of the pituitary gland (6). CRH

induces proopiomelanocortin (POMC) synthesis and adrenocorticotropic hormone

(ACTH) (148). ACTH stimulates the synthesis and secretion of adrenal steroid hormones

(glucocorticoids), especially cortisol, a major stress hormone affecting many tissues in the body, including the brain (6). Cortisol is the primary affecter of the HPA axis

activation in humans and regulates a broad range of physiological processes, including the anti-inflammatory response (31). It acts on two types of receptors found within the

brain: mineralocorticoid and glucocorticoid receptors expressed by different neurons (6).

Another important target for cortisol is the hippocampus, a major controlling center of the

HPA axis. Cortisol acts on the hypothalamus and pituitary gland in a negative feedback cycle to suppress CRH and ACTH production (148). The release of CRH from the hypothalamus is influenced by stress, by blood cortisol levels, and by the sleep/wake cycle (6). Besides the role in the release of ACTH, CRH serves as a neurotransmitter in the brain that mediates sympathetic arousal, providing an important link between the 9

adrenocortical and autonomic branches of the stress response (6). Glucocorticoid hormones are capable of inhibiting or down-regulating cytokines, therefore acting as powerful immune regulators (126). They initially stimulate the immune system and then help return it to baseline. It is only with major stressors of long durations or with major exposure to glucocorticoids that the immune system does not return to baseline but into immunosuppression (126). Cytokines and receptors are expressed in the hypothalamus and anterior pituitary cells, where they regulate pituitary development, cell proliferation, and hormone secretion (6). They behave as immune-neuroendocrine modulators by converting signals that interface stress and inflammation with the HPA axis (146).

Cytokines have been shown to elevate plasma ACTH and glucocorticoid levels in both animals and human (62, 106, 113). Excessive HPA axis stimulation leads to immunosuppression and consequently, to an increase susceptibility to infection, thus the negative regulation of pituitary cytokine function is critical (7). Overall, HPA axis activation during inflammation is an important protective mechanism to stress.

SAM axis on immune response

In response to the activation of the SAM axis, catecholamines are released (31).

They work with the autonomic nervous system to exert regulatory effects of the cardiovascular, hepatic, and skeletal muscle; along with a variety of immune functions including cell proliferation, cytokine and antibody production, cytolytic activity, and cell trafficking (76, 129). In humans, approximately 80% of the catecholamine released is epinephrine (55). If acutely activated, the SAM axis can provide the body with a needed 10

boost to deal with an immediate threat. The typical and most obvious threat of the stress-

induced epinephrine and norepinephrine is the fight-or-flight response, in which there is

an increased heart rate and blood flow to skeletal muscles. If the SAM axis is chronically

activated these molecules can dysregulate immune function (50).

Stress and emotions have been known for some time to be associated with

substantial physiological changes, including the activation of the two major stress

systems, the HPA and SAM (108). These two systems mediate the effects of stress on

disease and are engaged during stressful encounters (31). Prolonged or repeated

activation of these systems can interfere with their ability to control other physiological

systems resulting in an increased risk for physical and psychological disorders (30). The

effects of stress on the regulation of the immune and inflammatory processes have the potential to influence depression, infections, autoimmune, and coronary artery disease

(54). Evidence has suggested that psychological stress alters the immune system via

direct innervations of lymphatic tissue, through the release of the HPA and SAM

hormones that bind to and alter the functions of immunologically active cells, or through

stress-induced behavioral changes (31).

Heart Rate Variability and Autonomic Interaction

Heart rate variability (HRV) is thought to be an indicator of the balance of the sympathetic and parasympathetic nervous systems (123). HRV is the beat-to-beat fluctuations in heart rate or variations in consecutive R-R intervals (148). The amplitude 11

and to a lesser degree the frequency of the fluctuations have been shown to continuously change as response of cardiovascular control systems via the autonomic nerves (114).

Fluctuations above 0.15 Hz are due to vagal activity only, whereas fluctuations below

0.15 Hz are mediated by both cardiac vagal and sympathetic fibers (114). This quantitative information of autonomic control can be obtained from HRV. High frequency (HF) and low frequency (LF) are two components of HRV that estimate cardiac vagal (degree of parasympathetic activity) and sympathetic activity (114).

Agreement exists that the HF peak is a good index of vagal activity, thus a decrease in

HF reflects the decrease in vagal activity (21). The interpretation of LF peak is a bit more controversial as an expression of sympathetic activity because of the role of both branches in mediating fluctuations below 0.15 Hz (114). Nevertheless, an increase in LF has been shown to occur during mental stress when sympathetic activity increased (85).

The LF/HF ratio is a marker of autonomic balance.

Depression and Anxiety

Depression and anxiety are two of the most common mental health disorders, with an estimated prevalence of 10-20% at any given period (23). An individual’s personal, social, and occupational functioning, as well as physical health, can be affected considerably by these disorders (37). According to the American Psychological

Association, anxiety is defined as an emotion characterized by feelings of tension, worried thoughts, and physical changes. Individuals suffering from anxiety generally have intrusive, recurring thoughts or concerns that may lead to the avoidance of certain 12

situations out of worry. Individuals with anxiety disorders may experience a variety of

physical symptoms such as elevated blood pressure, sweating, trembling, dizziness, and

an elevated heart rate. The Anxiety and Depression Association of America claim that 40

million adults, ages 18 and older, suffer from anxiety. Anxiety develops from a variety of

complex risk factors including a genetic predisposition, brain chemistry, personality, and

life events (40). Anxiety has been included in the socio-biological organizations for its

probable adaptive values, as it signals potential danger and can contribute to mastery of a

difficult situation and thus personal growth (57). Excessive anxiety, on the other hand, is

maladaptive, either because it is too intense or because it is inappropriately provoked by

events that present no real danger (57). Anxiety becomes pathological when thoughts

become excessive and no longer serve to signal danger. It is considered a major

component of an unhealthy lifestyle and contributes to the pathogenesis of not only

psychiatric but also systemic disorders (66, 130). Therefore, it is important to reduce the

level of anxiety as a part of the prevention and management of disease.

Depression affects the way one thinks, feels, behaves, and functions (147).

Individuals suffering from depression may experience a lack of interest in daily life, have

an inability to concentrate, experience feelings of worthlessness or excessive guilt, and

express recurrent thoughts of death or suicide. They may experience a lack of energy,

significant weight loss or gain, insomnia or excessive sleeping (41). The Anxiety and

Depression Association of America states that at any given point in time, 3-5 percent of people suffer from major depression and the lifetime risk is about 17% (147). Depression 13

is often a chronic relapsing condition, with relapse rates of 50-80% in those who have been depressed in their lifetime (147).

It is not uncommon for someone with an anxiety disorder to also suffer from depression or vice versa. Mood and anxiety disorders tend to be chronic and highly co- morbid with each other (5). Approximately 20-25% of persons who experience major stressful events develop depression and/or anxiety (31). Reduced HRV has been noted in patients with depression and anxiety, indicating decreased activity of the parasympathetic nervous system and increased activity of the sympathetic nervous system (78). Numerous studies have supported and demonstrated the efficacy of yoga and aerobic exercise interventions as methods of managing and reducing stress, anxiety, and depression (155).

While modern medicine has the ability in many cases to heal physical diseases and alleviate psychological disorders, it is argued that purely a medical approach is far less effective in healing the emotional, intellectual, and personality layers of the human entity

(155).

Yoga

Yoga is an ancient discipline designed to bring balance and health to the physical, mental, emotional, and spiritual dimensions of an individual (123, 135). The Sanskrit name for yoga is “yuj” which means union, to join, to direct, and concentrate one’s attention (155). Yoga means union of our individual consciousness with the universal divine consciousness in a super-conscious state known as Samadhi (149). The reflection 14

of the union of the body, mind, and spirit is what differentiates yoga from general

exercise programs (43). The goal of the ancient traditional yoga is the stilling of

restlessness in the mind and the joining of the mind, body, and spirit in the search for

healing self-awareness and spiritual attunement (33). Although yoga developed from and

within Indian philosophy and religion, the practice of yoga itself does not require spiritual

beliefs or religious observation (99). An internationally renowned ashtanga yoga

instructor, Sharath Jois, stated that “yoga itself does not have religion; it is the

transformation for well-being.” The main goals of yoga are to achieve tranquility of the

mind and create a sense of well-being. Yoga suspends the fluctuations of the mind and it

is believed that by acting consciously, we live better and suffer less (155).

Yoga was first described by Patanjali in the classic text, Yoga Sutras (13, 79).

Patanjali defined the purpose of yoga as the knowledge of the true “self’ (16). Yoga

Sutras outlined the eightfold path to awareness and enlightenment called Ashtanga, which

means “eight limbs” (79, 81). The eight limbs are comprised of ethical principles for

living a meaningful and purposeful life (79, 81, 155). They direct attention towards one’s

health while acknowledging the spiritual aspects of one’s nature (155). The eight limbs

are yama (universal ethics), niyama (individual ethics), asana (physical postures),

pranayama (breath control), pratyahara (control of the senses), dharana (concentration), dyana (meditation), and sakadhi (bliss) (93). It is thought that each limb is connected as a whole, in the same way that bodily limbs are all connected. 15

There are four basic principles that underlie the teaching and practices of yoga’s healing system. First, it is important to keep in mind that the human body is a holistic entity comprised of interrelated dimensions that are inseparable from one another (41).

Secondly, every individual and their needs are unique and must be approached in a way that acknowledges this individuality (41). Yoga is self-empowering; the student is their own healer (28). Thirdly, the healing comes from within; yoga only assists in engaging the healing process (155). Lastly, the quality and state of an individual’s mind is crucial to healing, a positive mind state leads to a faster recovery.

Components of yoga

Yoga consists of a complex system of spiritual, moral, and physical practices aimed at attaining ‘self-awareness’ and well-being (117). Integrated yoga practice includes aspects of exercise (asanas), breath manipulation (pranayama), and relaxation

(meditation) (74). It is thought that by unifying the physical body, breath, and concentration while performing postures will clear the blockages in the energy channels of the body and the body’s energy system will become more balanced (33). All the components of yoga play a role and work together collectively to produce the multi­ dimensional positive effects (74).

Asanas are the physical postures that stretch and strengthen different parts of the body. An asana may be one of two types: dhyanasana and shasthyasana. Dhyanasana are postures that keep the spinal cord free and shifts the center of gravity (135). Shasthyasana 16

are the postures that lead to a healthy body (135). Each asana has a purpose, some postures message and bring fresh blood to the internal organs, while simultaneously rejuvenating the nervous system and lubricating the joints, muscles, and ligaments (6).

Others stimulate the nervous and circulatory systems that promote coordination and concentration, and calm the body.

Pranayama involves a variety of techniques for the regulation of breathing (68).

The Sanskrit word ‘prana’ refers to the light force (33). Breathing techniques combine inhalation, breathe retention, and exhalation (67). Inhalation is the process of receiving life energy, retention of breaths holds that energy, and exhalation empties all thoughts and emotions (68). They can be slower, more regular, or more refined. Common yogic breathing includes the complete yoga breath (conscious breathing in the lower, middle, and upper portions of the lungs); interval breathing (duration of inhalation and exhalation are altered); and alternate nostril breathing (33). Breath awareness and synchronization of movement and breath are important in performing the physical postures of yoga (33).

Meditation originated in Asian cultures and is a core component of Buddhism. It was derived from the word “meditari” meaning to think, to dwell upon, and to exercise the mind; as well as the word “mederi” which means to heal (48). The Sanskrit derivation is “medha”, meaning wisdom (48). Meditation is a mental process involving voluntary concentration of thoughts aimed at producing an altered state of awareness that is believed to produce changes in perception, attention, and cognition (122). One of the more commonly explored types of meditation is Mindfulness Meditation (MM). MM 17

originated from ancient Buddhist and Yoga philosophies as a form of Eastern

contemplative practices (48). Mindfulness refers to the process of intentionally bringing

attention, in a nonjudgmental manner, to the internal and external experiences that exist

in the present moment (27). The three fundamental components of mindfulness are

intention, attention, and attitude. Intention involves motivation and knowing the

conscious direction and purpose (136). Attention relates to the moment-to-moment

knowing of what is happening as it is actually happening (136). The attitude aspect

describes how one pays attention and refers to accepting, caring, and discerning qualities

of mindfulness (136). Heightened mindfulness creates a better awareness of sensations,

thoughts, consciousness, bodily states, and the environment while simultaneously

encouraging openness, curiosity, and acceptance (48). It is a process that allows the mind

to be still to permit a greater sense of awareness to the present moment. MM is intended

to cultivate continuous and clear attention to ongoing subjective experiences in

combination with an attitude of acceptance and openness to whatever experiences may

arise (48). The key elements of MM are the ability to intentionally attend to the present

moment regardless of the content observed; the ability to recognize and accurately label

emotions, and creating a refined self-awareness (71). It allows individuals to detach from

thoughts and feelings to gain better insight, awareness, and compassion in order to

facilitate a more flexible and adaptive coping response to stressors (48). Regular practice

of all these techniques is considered to clear body energy channels, improve circulation to vital body organs, promote stillness, and concentration (33, 67). 18

Hatha yoga

In the Western world, the most common aspects of yoga practice are the physical

postures and breathing practices of Hatha Yoga and meditation. It is the most popular

and widely used form in the West, and is a disciplined, individually paced form of yoga

that places more focus on transitional postures, as well as breathing and meditation (121).

It was developed by T. Krishnamacharya in the first part of the 20th century (37). There

are numerous styles of Hatha such as Ashtanga, Iyenger, Intergral, and Kripaln (33).

Most people begin with Hatha yoga in order to promote relaxation, enhance flexibility, or

to heal a body injury (131). It enhances the capacity of the physical body through a series

of body postures, movements, and breathing techniques (33). The physical postures are

performed while standing, sitting, or lying prone or supine on the floor and take each joint through a full range of motion (131). The postures involve bending, twisting, and

balancing of the body, consequently improving flexibility and strength (117). The

controlled breathing helps to focus the mind and achieve relaxation while meditation

aims to calm the mind (121). The aim of Hatha Yoga is to free the body of physical

limitation and to restore balance to the body (131). Frequent mental distress is

increasingly prevalent among U.S. adults; Hatha yoga has claimed to induce stress-

reduction and empowerment in practicing subjects (100).

Benefits of yoga 19

Since the 1970s, meditation and other stress reduction techniques have been studied as possible treatments to promote well-being (135). The earliest reported benefit of yoga in alleviating mood and anxiety symptoms was published by Girodo in 1974

(37). As participation rates in mind-body fitness programs continue to increase, it is important for healthcare professionals to be informed about the nature of yoga and the evidence of its therapeutic effects. Mind-body fitness combines muscular activity and an internally directed mindful focus on awareness of the self, the breath, and energy (33).

Therapeutic yoga is defined as the application of yoga postures and practice to the treatment of health conditions (155). It involves instruction in yoga practices and teachings to prevent, reduce, or alleviate structural, physiological, emotional, suffering, and limitations. Improved flexibility is the first and most obvious benefit of yoga (90). It has been shown to promote strength and endurance, improved concentration, self- confidence, efficacy, lowered irritability, and facilitates in friendliness, compassion, greater self control, and encourages an optimistic outlook by cultivating a sense of calmness and well-being (84). A study on two-weekly (90 minute) yoga sessions over two months, was able to determine the effectiveness of yoga as a tool for reducing anxiety levels (70). The researchers suggested that yoga encourages individuals to become aware of their body’s tension throughout specific body postures. By raising awareness of the body and in learning a method by which stress can be reduced, yoga may serve to increase self-confidence by promoting a personal sense of control (70).

Stress, anxiety, depression, and other psychological debilitating conditions have been 20

associated with cognitive deficits (11). It has been suggested that yoga plays a role in cognitive aspects of psychological functions such as memory improvement (4); it is thought that mind-body techniques can have potential beneficial effects on cognition because they involve active attention exercises (70). Rocha et al. (2012) found reductions in parameters related to stress, depression, and anxiety, as well as improved memory after six months of yoga practice. A study performed on the effects of yoga, over a three-month period, demonstrated improvements in psychological status with significant decreases in scores of anxiety, depression, anger, along with improvements in well-being and significant decrease in sympathetic activity (74). Yoga appears to be an effective method for improving health, and in the prevention and management of diseases.

Yoga has been shown to be a simple and economical therapeutic modality for disease. Viewed as a holistic stress management technique, yoga is a form of complementary and alternative medicine that produces a physiological sequence of events in the body to reduce the stress response (153). The practice of yoga produces a physiological state opposite to that of the flight-or-fight stress response (24). It interrupts the stress response to create a sense of balance and union between the mind and body

(155). Mental health problems such as depression, anxiety, stress, and insomnia are among the most common reasons for individuals to seek treatment with complementary therapies such as yoga (117). Yoga encourages one to relax, slow the breath, and focus on the present moment. It shifts a balance from the sympathetic nervous systems to the 21

parasympathetic nervous systems. The precise mechanism by which yoga causes this shift has yet to be determined but it has been hypothesized to be via direct vagal stimulation (65). By regular practice of the relaxation (parasympathetic) response it increases individual’s resilience to stress (36). Poses that twist and compress organs help message and rejuvenate immune organs and channels by generating balanced energy that is vital energy for the immune system (6). Yoga has been shown to increase blood flow to the intestines and vital organs, therefore increasing levels of hemoglobin and red blood cells which allows for more oxygen to reach body cells thus enhancing their functions

(155). Studies have shown significant decreases in breathing, heart rate, and blood pressure suggesting that yoga has an immediate quieting effect on the HPA axis response to stress (89, 134). An eight-week study on yoga found psychological benefits in mildly depressed patients by inducing an immediate effect on cortisol levels indicating a direct effect on the HPA axis (100).

Yoga has been shown to have an immediate effect on decreasing anxiety (100,

123, 151) and increasing feelings of emotional, social, and spiritual well-being (102). A study on college students and the effects of yoga found reductions in anxiety and irritability scores, improvements in concentration, self-confidence, attentiveness, and an optimistic outlook following yoga practice, suggesting that yoga can be beneficial in achieving a tranquil state of mind during routine activities (84). This study also indicated improvements in concentration and arousal that was essential in demanding or stressful situations like examinations. The researchers emphasized that in challenging situations a 22

certain element of anxiety is beneficial because individuals perform best under optimal

stress but with any additional stress, performance deteriorates. Findings have suggested

that yoga produces these beneficial effects by the inhibition of the posterior or

sympathetic area of the hypothalamus (155). This inhibition optimizes the sympathetic

responses to stressful stimuli and restores autonomic function regulatory reflex

mechanism associated with stress (155). It reduces the areas responsible for fear,

aggression, and rage, and stimulates the rewarding pleasure centers of the brain leading to

bliss and pleasure. Studies have shown that this inhibition results in lower anxiety, heart

rate, respiratory rate, blood pressure, and cardiac output in students practicing yoga and

meditation (10, 16, 41). Yoga further improves cardiovascular efficacy and homeostatic

control of the body and results in improved autonomic balance, respiratory performance, psychological profile, and overall well-being (16).

Yoga practice has been shown to reduce the impact of the exaggerated stress responses associated with anxiety and depression by the down regulation of the HPA axis

(135). The HPA axis generally triggers as a response to physical or psychological demands, leading to a cascade of physiological, behavioral, and psychological effects

(25). This response leads to the mobilization of energy needed to combat the stressor through the classic fight-or-flight response (135). Over time, the constant state of alertness, resulting from repeated firing of the HPA axis, can lead to dysregulation of the immune system and ultimately lead to various diseases and disorders (94, 132). 23

It appears that yoga reduces perceived stress and anxiety by adapting the stress

response systems which in turn decreases physiological arousal and increases HRV (135).

This response demonstrates the body’s ability to be more flexible in response to stress. A

study evaluating the effects of fifteen minutes of stretching in Hatha yoga over four-

weeks found a significant increase in HRV and a marked decrease in heart rate (100).

This study determined that increased flexibility correlated with improvements of cardiac

autonomic function. A German study published in 2005 analyzed individuals over weekly

(90 minute) yoga classes for three months, and found (based on self-reports)

improvements in perceived stress, depression (50%), anxiety (30%), energy, fatigue, and

well-being (65%), indicating a substantial effect of the yoga class on psychological

outcomes (123).

A growing body of evidence supports the belief that yoga benefits physical and

mental health via down-regulation of the HPA axis and SAM axis (74, 123). Brief yoga- based relaxation training normalizes the function of the autonomic nervous system by

moving both the sympathetic and parasympathetic indices toward a more normal region

(117). Yoga postures (asanas) are low intensity usually non-strenuous exercises which affect the HPA axis positively by bringing down sympathetic stimulation and

significantly decreasing the release of catecholamine’s (74). Yoga practice may inhibit the activity of the paraventricular nucleus of the hypothalamus, which in turn affects the anterior pituitary gland to produce less ACTH (6). A decrease in ACTH decreases the synthesis of cortisol by the adrenal gland (72). Cortisol activates the enzyme 24

phenylethanolemine N-methyltransferase (PNMT), which converts norepinephrine to epinephrine (9). With a decrease in cortisol it consequently inhibits sympathetic tone and a decrease in catecholamine formation (6). Decreased levels of corticosteroids and catecholamine’s are known to therefore decrease the stress response (6). It is thought that reduced sympathetic activity and improved parasympathetic drive the normalization of the HPA axis (20).

Although a clear mechanism of change has yet to be identified or empirically supported on a consistent basis, the slow and deep breathing exercises involved in meditation are thought to alleviate bodily symptoms of distress by balancing the sympathetic and parasympathetic nervous system responses, thereby modifying cardiac ventricular activity (37). Meditation has been seen to affect the autonomic nervous system which controls and regulates the overall feeling state of the body through its two systems, the sympathetic and parasympathetic. The sympathetic system activates the body and releases stored energy; and the parasympathetic governs the relaxation, recuperation, and digestive system of the body (63). Meditation involves the intentional and repeated practice of deliberately activating the body’s relaxation response

(parasympathetic), which then counteracts the sympathetic response allowing one to manage stress in an appropriate manner (48).

Among various approaches to reduce the levels of anxiety or depression, yoga is one that combines the physical elements of a healthy lifestyle with prescriptions for abiding mental peace (57). Although the mechanism that mediates the therapeutic 25

benefits of yoga has yet to be clarified specifically, it has been suggested that yoga-based

guided relaxation helps in the reduction of sympathetic activity through the reduction in

heart rate, oxygen consumption, and increase in breath volume, which are the clinical

signs of neurohormonal activity, thus facilitating in the protection effect (135). By

managing stress, especially chronic or long-term stress, through the practice of various

relaxation techniques it may help individuals overcome other co-morbidities associated

with disease and lead to a better quality of life even during periods of stress (6).

Aerobic Exercise

Aerobic exercises, such as running, swimming, and dance, involve prolonged

activity of large muscle groups. In many studies aerobic exercise is defined by physical

exercise implying a regular, structured, leisure-time pursuit (128). Although aerobic

exercise may be demanding and exhausting, individuals have stated that they feel good

after completing the exercise (91). Aerobic exercise is a complex psychobiological

stimulus, meaning that repeated exposure to uncontrollable stressors causes the body to

eventually become resistant to stress, but with exposure to controllable stress this can be

achieved more quickly (83). Aerobic exercise is considered a controllable stressor that

challenges homeostasis by stimulating the sympathetic nervous system to release

adrenaline and noradrenaline (45). It produces many of the same bodily sensations that often elicit anxiety reactions such as an increase in heart rate, respiration, and perspiration (17). It has been suggested that mild repeated stressors may be health promoting by affecting neural networks that are shaped by prior experience, resulting in 26

altered regulations in response to future stress (125). Researchers believe that by

repeated exposure to anxiety related interceptive stimuli, through exercise, may therefore

eliminate the fear response (17).

Benefits of aerobic exercise

Although exercise is regarded, in most research, as a purely physiological

stimulus its emotional effects depend intimately on social and other environmental cues

as well as the expectations of the individual (15, 98). A typical duration of training programs in psychological literature is around 10-12 weeks, reflecting the minimum

period necessary for positive effects (128). Evidence that physical activity is enjoyable

emerged when mood was measured immediately before and after exercise, and was related to lower perceived stress in day-to-day life (140). Cross-sectional studies have

consistently demonstrated the association between high levels of physical activity and better mental health. Steptoe et al. (1997) found, based on self-reported measures of

16,483 undergraduate students, exercise correlated with lower depression rates (139). A

similar study based on self-reported measures of 55,000 individuals found a correlation between recreational activity and better mental health, including fewer symptoms of both anxiety and depression (138). Longitudinal surveys have further confirmed definitively that exercise habits do predict later freedom of stress, anxiety, and depression. A study performed on 4,848 individuals found that an absence of exercise habits was linked to depression later in life across two successive nine-year periods (22). Stewart et al. (1994) evaluated self-reported measures based on 1,758 participants and found that exercise 27

predicted a range of positive health outcomes two years later, including, well-being and

lower levels of anxiety, depression, and fatigue (141). These positive effects have even been seen to last up to 25 years based on a study performed by Paffenbarger et al. (1994)

(110). This suggests the possible long-term psychosocial effects associated with aerobic % exercise that serves to relieve depression and anxiety (91).

Meta-analyses of a variety of studies have estimated that depression scores decrease by between 0.3 to 1.3 of a standard deviation after exercise training in comparison with a variety of control conditions (35, 107), and have also indicated an anxiolytic effect with aerobic exercise training (80, 92, 116). Depression is associated with low levels of norepinephrine, therefore it has been suggested that aerobic exercise may facilitate in the production of that neurotransmitter substance and thereby relieve depression (91). McCann et al. (1984) performed a 10-week study on the effects of aerobic exercise on depression and found that the running group showed greater reductions in depressive symptoms when compared to the no treatment group (91).

Similarly, Brown et al. (1979) assessed depression in subjects that were placed in a jogging or control group, and found a reliably greater decline in depression in the jogging group (19). Aerobic exercise is associated in reduced generalized arousal of anxiety sensitivity, including heart rate and muscle tension (1). Anxiety sensitivity is described as an enduring fear of anxiety and anxiety related sensations brought about from the belief that these sensations can have harmful physical, psychological, or social consequences

(119). A non-experimental study found an inverse relationship between exercise 28

frequency and anxiety sensitivity (96). The researchers suggested a possible explanation for this effect to be due to the fact that exercise produces physiological sensations similar to those feared by individuals with high anxiety sensitivity and it is therefore avoided by participation in exercise (96). Alternatively, the lack of exposure to these sensations, resulting from physical inactivity, promotes anxiety sensitivity (17).

Literature assumes that because exercise training reduces the cardiovascular response to physical stress by improving individual’s fitness level, that it should have a similar effect in psychological stress (128). Research has shown that exercise that is more intense than that of the participant’s habitual level is less likely to improve mood and is liable to worsen the symptoms (156). It has been indicated that anxious mood is reduced by mild exercise training, which is insufficient to increase fitness level; whereas training that is sufficiently intense improves fitness level but is less effective at relieving anxiety

(103). Furthermore, in studies by Roth and Homes (1987) and McCann and Homes

(1984), depression declined within five weeks of training before fitness measures had even changed (91, 124). Overall, these findings suggest that cardiovascular responses do not correlate with mood changes. Conversely, a study by Broman et al. (2004) analyzed the beneficial effects between high and low intensity exercise and found that although both types were successful on average at decreasing overall anxiety sensitivity, the high intensity exercise produced a more rapid reduction over a two-week period (17). Results may have been influenced by the environment of the activity such as social engagement in group based exercise. An increase in social activity is likely to have been a critical 29

feature of exercise. A growing body of evidence has indicated that aerobic exercise is an

effective, accessible, cost-efficient, behavioral manipulation that acts to alleviate

symptoms and reduce the occurrence of stress-related mood disorders (56). Overall, it has

been shown that aerobic exercise is an ideal treatment alternative for a variety of anxiety

and mood disorders.

It is now well accepted that habitual physical activity significantly reduces the

incidence and severity of stress-related mood disorders, such as depression and anxiety

(56). It is believed that physical exercise training produces a protective element from the

harmful effects of stress and the resulting loss of the protective benefits of exercise could

further intensify the response to major stressors (128). Diverse explanations have been proposed for the psychological effects of exercise training. It has been suggested to be due to changes in body temperature or cerebral blood flow, improvement in self-esteem, distractions from negative thoughts, or improved retrieval of positive thoughts (42). The protective effect of exercise against depression or anxiety are large, in fact it is equal to that of the well known protective effect of exercise against cardiovascular disease (107).

Although evidence suggests that exercise can prevent the development of depression and anxiety, the underlying mechanism of this effect remains unsolved (56). Many studies have indicated that after exercise, blood pressure falls below pre-exercise levels (59, 118,

120) and heart rate stays elevated for hours after exercise (46, 73). The mechanism underlying post-exercise hypotension remains controversial (143). It is proposed that after aerobic exercise, the increase in heart rate during the recovery period has been 30

attributed to a persistent increase in sympathetic modulation and a decrease in

parasympathetic modulation to the heart (60). Despite its well-proven acute hypotensive

effect (low blood pressure), evidence is mixed as to whether cardiovascular or

sympathoadrenal responses to psychological stress are reduced by exercise (128).

Endurance training leads to cardiovascular, metabolic, and hormonal adaptations to ensure that there is minimal homeostatic disruption during exercise (150). The HPA

axis is both stimulated by exercise and subjected to adaptation with exercise training by

influencing CRH, ACTH, and corticosterone (109,114). Further indication of the adaptive response of the HPA axis via autonomic activity has been shown by analyzing the HRV effects during exercise (87). Surprisingly, changes in HF and LF powers and the LF/HF ratio observed during exercise have not been shown to decrease vagal activity with increasing the level of intensity (114). One of the first studies on HRV during exercise expected that HF would progressively decrease with intensity indicating a decrease in parasympathetic activity and LF activity would increase implying sympathetic dominance (114). In contrast, HF power was substantially unchanged from rest up to

70% V02Max and LF power significantly decreased at medium-high intensity. Even with these results, the LF/HF ratio clearly indicated sympathetic dominance occurred in autonomic interaction, which is to be expected because exercise produces the stress response (114). Another study analyzed eight-weeks of aerobic training and found that it induced an increase in VO2 peak, a decrease in resting heart rate and arterial pressure, with no change in HRV parameter in elderly subjects (114). This evidence suggested that 31

HRV does not appear to be increased in a dose-dependent manner with increasing levels of physical activity leading to a different outcome than researchers would have expected

(97). These findings may underlie the protective and adaptive effects of exercise training on the hyper-responsiveness of the HPA axis to behavioral stress (87).

Yoga versus Aerobic Exercise

Aerobic exercise, such as running, involves the prolonged activity of large muscle groups; while anaerobic exercise, such as yoga, involves more intense, brief, and non­ sustained movements (128). Yoga, although not entirely risk free, can be considered a safe form of exercise if practiced under the guidance and supervision of a qualified trainer (135). Evidence is growing that yoga practice is a low-risk, high-yield approach to improving overall health. The usual measure of fitness in psychological research has been in aerobic exercise (128). The practice of yoga has now been shown to improve mood in a way comparable to aerobic exercise (70). Over the years non-strenuous procedures, such as relaxation and flexibility training, have been designed to be comparable with exercise for skill mastery, distraction from normal activities, or social interaction (128). Studies comparing the effects of yoga and conventional exercise seem to indicate that yoga may be as effective as, if not even better than exercise at improving a variety of health related outcomes (117). For many individuals dealing with stress yoga may be a very appealing way to better manage symptoms (135). 32

Meditation and relaxation techniques have produced similar improvements in

self-rated depression as compared to exercise training (78). Moderately-intense aerobic

exercise and low-intensity yoga are well known to lower blood pressure, the mechanism

by which they induce blood pressure reductions may be attributed to their beneficial

effects on the autonomic neurological function (135). While aerobic exercise has been

shown to improve parameters of fitness, yoga has improved fitness levels in strength,

endurance, flexibility, and VChmax (145). Yoga techniques are known to improve overall

performance and work capacity (137). Evidence has suggested that yoga interventions

appear to be equal and/or superior to exercise in nearly every outcome measured (123).

In two well-controlled studies looking at the reduction of depressive symptoms,

over 11 weeks of aerobic training in comparison with relaxation, strength, and flexibility,

found a similar correlation between both types of exercise in reducing symptoms (124,

140). During a follow-up period the effects were maintained at three months. Chattha et

al. (2008) compared the effects of 8 weeks of daily yoga to walking exercises, and found

that the yoga group exhibited significant improvements in psychological, somatic, and

vasometer, while the exercise group improved significantly only in the psychological

factor (26). The yoga group also exhibited a significantly greater decrease in levels of

stress. A similar study compared 4 months of daily yoga to exercise, and found that both

groups exhibited significant reductions in psychotic symptoms but the yoga group

improved significantly better (47). A study looking at the short term effects of a single yoga class versus an aerobic dance class, found that the yoga group experienced 33

significant reductions in salivary cortisol while the dance class had a significant increase

in salivary cortisol level (151). These findings indicate that yoga and exercise may both

improve mood but affect the HPA axis differently (123).

Two studies have compared yoga with aerobic exercise in HRV response. Khattab

et al. (2007) compared HRV during a 60-min yoga class versus 60-minutes walking, and

found that yoga exhibited greater HRV particularly in the measures associated with parasympathetic tone (75). A 6 week, randomized control trial, was performed based on the belief that exercise and yoga exert different effects on the sympathetic nervous

system (14). Researchers discovered that HRV remained unchanged in the cycling group while there were significant changes in the yoga group. A change in the HRV by the yoga practice supports the notion that yoga acts on the sympathetic nervous system by increasing parasympathetic arousal (14).

Differences between yoga and aerobic exercise may be a result of how the two differ in their effects upon the HPA axis (123). Low-intensity exercises have repeatedly been shown to lower cortisol levels (38, 52), while high intensity exercise leads to proportional increases in cortisol (64). Perhaps this is why yoga, involving slow and often non-strenuous activity positively affects the HPA axis response to stress by lowering sympathetic stimulation, therefore lowering levels of norepinephrine and epinephrine

(134). Aerobic exercise, on the other hand, appears to stimulate the sympathetic nervous system, therefore raising plasma epinephrine and norepinephrine (13, 115). It is possible that yoga might not only be an acceptable addition to care, but an effective, feasible, and 34

accepted alternative to exercise (123). Similarly to exercise, yoga has advantages in that it is cost-effective, non-invasive, has minimal risk of adverse effects or drug interactions, does not require medical supervision for practice, and has added benefits of improving physical fitness (37).

Study Rationale, Purpose, and Hypotheses

Stress is a major issue for college students as they struggle to balance a variety of academic, personal, and social pressures. The increase in stressful life events in college students has been associated with anxiety and depression (39). Research on college students supports the relationship between heightened levels of stress that alter behavioral patterns leading to a compromised health (104, 127). Given the fact that clear evidence exists regarding the efficacy of both aerobic exercise and yoga interventions in alleviating various symptoms and improving outcomes, it is surprising that researchers have not discriminated more clearly between the effects of the two on improving mental well­ being.

The purpose of this study was to evaluate and compare yoga and aerobic exercise in its effects of promoting mental well-being in college students. This study will specifically compare mental well-being and autonomic nervous system function in college students enrolled in yoga and aerobic activity type course. It is hypothesized that the students engaged in the yoga course will experience improved well-being and the individuals who participate in the activity for longer periods of time will experience mental well-being. 35

METHODS

Participants:

The participants were recruited from activity courses at San Francisco State

University, during the fall 2014 semester. There were a total of 334 subjects

(aerobic=T86, yoga=148) that participated. Thirty-four individuals (aerobic=18, yoga=14) were randomly selected from the large pool of individuals to have physiological measures performed. Two of the individuals were excluded from the study due to abnormal heart rhythms. Individuals were selected based off of indicated interest.

All participants were 18 or older, and had no major health conditions that would impair their ability to participate in each of the exercise courses. All participants read and acknowledged the risks, both physical and mental involved in their participation in exercises courses on the San Francisco State University campus.

Inclusion/Exclusion Criteria:

All participants had to be enrolled in one of the selected activity courses at San

Francisco State University in order to participate in the study. They were excluded if they had any current health conditions that could put them at a potential risk of injury with participation in the exercise courses. Individuals selected for physiological measures were excluded if they were currently taking anti-depressants, anti-anxiety medication, and/or medication for ADHD because of the drug’s effects on the autonomic system.

Procedures: 36

Participants enrolled in activity courses (KIN 100- Aerobic low impact, KIN 103-

Aerobic Step, KIN 139- Jogging, KIN 136- Hatha Yoga) who volunteered to participate

were separated into two groups based on the type of activity course (yoga and aerobic

exercise). In order to assess individuals’ mental well-being they were required to fill out

five self-reported questionnaires during the normal date, time, and location of the activity

course. The questionnaires given were the Penn State Worry Questionnaire, Subjective

Happiness Scale, Perceived Stress Scale, Subjective Vitality Scale, and the Mindful

Attention Awareness Scale.

In the information section, at the conclusion of the questionnaires, there was a

question asking if the individual would be interested in participating in physiological

measures. If the individual answered “yes”, they had the potential to be randomly

selected to have two physiological measures done. Physiological measures obtained were body composition and a 10-minute resting three-lead ECG.

Body Composition Procedure

Body composition was assessed by using a machine called the BodPod®

(Concord, CA). Individuals were instructed to wear tight fitting clothing to ensure most accurate reading. They were placed in the machine which took approximately 5-minutes.

The variables obtained were body fat and fat-free mass percent.

Heart rate Variability Procedure 37

A 5-minute electrocardiography (ECG) tracing was obtained using the Biopac

MP150 Data Acquisition System (San Francisco, CA) while the participant rested in a supine position. The ECG was inspected for irregular beats and if any were found they were removed. A spectral analysis was performed using an autoregressive algorithm. The power spectrum was analyzed for total power (TP) with a power range of 0.0-0.4 Hz,

Low Frequency (LF) power with a power range of 0.04- 0.15 Hz, High Frequency (HF) power with a range of 0.15- 0.4 Hz, and the LF/HF ratio. TP is the integrated power in the observed spectrum between the lower frequency edge and the upper frequency edge of the high frequency. LF is an indicator of the sympathetic system while HF is associated with a heightened parasympathetic system. The LF/HR ration is used to assess autonomic balance.

Statistics:

All quantitative information was analyzed using a one-way ANOVA. The findings were found using Pearson Correlation. An Independent T-test was used to assess all physiological measures. A significance level of < 0.05 was used for all the tests.

RESULTS

Survey Results

The questionnaires given to analyze the overall well-being of individuals participating in either yoga or aerobic exercise looked at levels of mindfulness, worry, vitality, happiness, and stress. There were a total of 334 participants, of which 186 were 38

in the aerobic group (females=l 18, males=68) and 158 were in the yoga group

(females=l 16, males=32). When analyzing group differences in relation to the questionnaires there were no significant differences found on activity type and better overall well-being (Table 1, Graph 1). However, when the Pearson Correlation was performed there was a significant difference found between increased participation in physical activity (1.54 ± 0.82) (Table 2). This correlation was associated with decreased

levels of stress (Table 2). When putting activity type aside and assessing possible sex differences (Table 2), the data showed that females have significantly higher scores in stress levels than men (Graph 2).

Survey Figures and Tables:

Dependent Variable Yoga and Aerobic Mean Std. 95% Confidence Error Interval

Lower Upper Bound Bound

Aerobic 4.030 .057 3.917 4.142 Mindfulness Yoga 3.859 .064 3.733 3.984

Aerobic 51.251 .990 49.305 53.198 Worry Yoga 52.229 1.106 50.054 54.404

Aerobic 4.610 .085 4.443 4.777 Vitality Yoga 4.617 .095 4.430 4.803

Happiness Aerobic 4.969 .080 4.811 5.126 39

Yoga 5.118 .090 4.941 5.294

Aerobic 1.858 .048 1.763 1.953 Stress Yoga 1.886 .054 1.780 1.992

Table 1. Activity type differences between questionnaires.

60

Mindfulness Worry Vitality Happiness Stress

Figure 1. Exercise type versus survey differences. Mean ± Std. Error

Mindfulness Worry Vitality Happiness Stress

Activity 0.005 -0.039 0.096 0.034 -0.109* Level P = 0.928 P = 0.458 P = 0.064 P = 0.518 P = 0.038

Table 2. Pearson correlation between increased participation in activity and questionnaire scores; p-value < 0.05. 40

Dependent Variable Gender Mean Std. 95% Confidence Error Interval

Lower Upper Bound Bound

Mindfulness female 3.900 .052 3.798 4.002

male 4.038 .085 3.871 4.205

Worry female 54.558 .855 52.876 56.240

male 45.347 1.402 42.588 48.105

Vitality female 4.596 .077 4.445 4.747

male 4.702 .126 4.454 4.950

Happiness female 5.057 .073 4.914 5.200

male 5.074 .119 4.839 5.308

Stress female 1.948 .043* 1.863 2.033

male 1.681 .071 1.542 1.820

Table 3. Sex differences versus surveys. 41

Stress

2.05

■Female ■Male

Female Male

Figure 2. Difference between sex and stress levels.

Physiological Measures Results

In order to assess changes within the body associated with activity type individual’s heart rate variability was analyzed. Table 4 shows the participants’ descriptive information obtained for physiological measures. There were a total of thirty- two individuals (aerobic=18, yoga=14) included in the physiological testing, of those twenty -one were female and eleven were male. There were no group differences between groups within the descriptive information. Table 5 summarizes all the Heart

Rate Variability Indices between groups and is depicted within figures 3,4,5, and 6. There were no significant differences found in heart rate variability between groups.

Physiological Measures Figures and Tables:

Group Age % Fat Free Mass % Body Fat 42

Aerobic 22.83 ±0.97 76.84 ±2.40 23.16± 2.40 Yoga 22.00 ±0.93 73.88 ±2.45 8.45 ±0.64 Table 4. Descriptive information. Data are mean ±SD.

Group InLF InHF InTP LF-HF R-RSDNN

Aerobic 8.26 ±0.42 9.10 ±0.76 9.96 ± 0.97 ±0.62 968.23 ± 94.22 ± 0.62 47.62 9.97

Yoga 8.45 ±0.64 8.97 ±1.06 10.04 2.57 ±0.98 901.84± 85.95 ± ±0.88 23.55 13.98 Table 5. Heart Rate Variability Indices. Data are mean ± Standard Error.

10

9.5

Aerobic Yoga

Figure 3. High Frequency (HF) power between exercise type. 10

9.5

(N £c/i U« J c

7.5

7 Aerobic

Figure 4. Low Frequency (LF) power between exercise type.

Aerobic

Figure 5. Total power between exercise type. 44

10 -

8

Aerobic Yoga

Figure 6. LF/HF ratio between exercise type.

DISCUSSION

Based off the questionnaires given, there were no differences found between type of physical activity and a heightened state of well-being. However, there was a significant correlation between increased participation in physical activity and decreased levels of stress (20, 30). Prior research has stated that although both forms of exercise improve psychological well-being, yoga has been found to have a significantly greater decrease in stress levels (29, 55). Psychological research has shown that the minimum period necessary for positive effects is between 10-12 weeks (69, 128). Interestingly, the current research indicated that females had significantly higher stress levels than men. A study looking at stress on first-year undergraduate students in Australia (112) found that

52.9% of students were suffering from some degree of stress but with significantly more 45

female students than males which has similarly been observed on undergrads in Hong

Cong (154) and Turkey (8). Across nations and cultures, women of reproductive age are

approximately two times more likely to suffer from stress related symptoms than men

(105). Although the exact mechanism has yet to be determined, it is thought that there may be sex differences associated in the HPA responses to stress effecting coping behavior (142). It is also thought that social roles may play a part in increased levels of stress for females (88).

Overall the physiological measures that assessed heart rate variability had no significant differences between groups within all indices, meaning there were no differences between groups in autonomic control. The aerobic group had a slightly lower

LF/HF ratio when compared to the yoga group, indicating a heightened parasympathetic activity, although this difference was not considered significant. Studies performed by

Khattab et al. (2007) and Bowman et al.(1997), found greater HRV in yoga individuals particularly in measures associated with parasympathetic tone (16, 100). Both groups had similar heart rates indicative of healthy individuals (Aerobic: 968.2 ms= 62 bpm; Yoga:

901.8 ms= 66.5 bpm) which is to be expected for individuals who are physically active.

In conclusion, individuals who have been participating in physical activity for longer periods of time tend to have lower levels of stress. This may suggest that physical activity acts as a protective mechanism for the prevention of stress related disorders, such as anxiety and depression that are highly prevalent in college students. 46

Study Limitations

The current study had a few limitations that could have affected the results. The

yoga class met once weekly while the aerobic class met twice weekly. This may have had

an effect on the lack of differences between groups. The data was collected after students

had been participating in the course for 8-10 weeks which could explain the lack of

changes in the physiological and psychological parameters. The study also included a

wide range of activity levels from low to high fit ranges based off how long they had

been performing that particular activity. Individuals may have also been participating in

other forms of exercise throughout testing.

FUTURE RESEARCH

Future clinical trials are needed to further examine the distinctions between

aerobic exercise and yoga, particularly on how the two modalities may differ in the

effects on the HPA axis (123). There are several types/different styles of yoga, each with

distinctive challenges and varying levels of difficulty. Each style differs in the emphasis

placed on the various components of yoga. It has been suggested that future studies

analyze the relative effects of these different types of yoga on the HPA axis with acute

and chronic stress (123). It has also been recommended that future research identify which form of yoga-based intervention is most effective and what level of severity of

depression or anxiety are likely to respond the best. There is also a need for more 47

comparisons studies on the effectiveness of aerobic and anaerobic exercise on short-term and long-term psychological effects (117). 48

REFERENCES

1. Abadie, B. (1988). Relating trait anxiety to perceived physical fitness. Perceptual and Motor Skills, 67, 539-543. 2. Ader, R., Cohen, N., & Felten, D. (1995). Psychoneuroimmunology: Interactions between the nervous system and the immune system. The Lancet, 99-103. 3. Allen, M.E., and D Cohen. (1987). Naloxone blocking of running-induced mood changes." Annals of Sports Medicine, 3, 190-195. 4. Andrade, R.L., & Pedrao, L.J. (2005). Some considerations about nurse’s use of nontraditional therapies in psychiatric nursing care. Revista Latino-Americana de Enfermagem 13.5, 737-742. 5. Andrews, G. (2002). Deconstructing current comorbidity: Data from the Australian National Survey of Mental Health and Well-Being. The British Journal of Psychiatry 181.4, 306-314. 6. Arora, S., & Bhattacharjee, J. (2008). Modulation of Immune Responses in Stress by Yoga. International Journal o f Yoga, 7(2), 45-55. 7. Auernhammer, C. J. (1999). Autoregulation of pituitary corticotroph SOCS-3 expression: Characterization of the murine SOCS-3 promoter. Proceedings o f the National Academy of Sciences, 96.12, 6964-6969. 8. Bayram N., Bilgel N. (2008). The prevalence and socio-demographic correlations of depression, anxiety and stress among a group of university students. Social Psychiatry Epidemiology, 43, 667-72. 9. Betito,K., Diorio, J., Meaney, M., & Boksa, P. (1992). Adrenal Phenylethanolamine N-Methyltransferase Induction in Relation to Glucocorticoid Receptor Dynamics: Evidence that Acute Exposure to High Cortisol Levels Is Sufficient to Induce the Enzyme. Journal of Neurochemistry, 58.5, 1853-1862. 10. Bharshankar, J.R., Bharshankar, R., Deshpande, V., & Kaore, S. (2003). Effect of yoga on cardiovascular system in subjects above 40 years. Indian Journal o f Physiology Pharmacology 47, 202-206. 11. Birdee, G., Yeh, G., Wayne, P., Phillips, R., Davis, R., & Gardiner, P. (2009) Clinical Applications of Yoga for the Pediatric Population: A Systematic Review. Academic Pediatrics 9.4, 212-220.e9. 12. Black, P. H. (1994). Central nervous system-immune system interactions: psychoneuroendocrinology of stress and its immune consequences. Antimicrobial Agents and Chemotherapy, 35(1), 1-6. 13. Bloom, S., Johnson, R., & Park, D. (1976). Differences in metabolic and hormonal response to exercise between racing cyclists and untrained individuals. Journal o f Physiology, 258, 1-18. 14. Bowman, A. J., Clayton, R. H., Murray, A., Reed, J. W., Subhan, M. M., & Ford, G. A. (1997). Effects of aerobic exercise training and yoga on the baroreflex in healthy elderly persons. European Journal o f Clinical Investigation, 27(5), 443- 449. 49

15. Breus, M. & O'Connor, P. (1998). Exercise-induced Anxiolysis: A Test Of The "time Out" Hypothesis in High Anxious Females. Medicine & Science in Sports & Exercise 30.7, 1107-1112. 16. Brikel, D. & Edgren, L. (2000). Hatha Yoga: Improved vital capacity of college students. Alternative Therapeutic Health Medicine, 55-63. 17. Broman-Fulks, J. J., Berman, M. E., Rabian, B. A., & Webster, M. J. (2004). Effects of Aerobic Exercise on Anxiety Sensitivity. Behaviour Research and Therapy, 42(2), 125-136. 18. Brown, B., & Huss, W. (1973). Exercise and rate brain catecholamines. Journal of Applied Physiology, 30, 664-669. 19. Brown, R, Ramirez, D., & Taub, J. (1979). The prescription of exercise for depression." The Physician and Sports Medicine, 78, 35-45. 20. Brown, R., & Gerbarg, P. (2005). Sudarshan Kriya yoga breathing in the treatment of stress, anxiety and depression. Journal of Alternative Complementary Medicine, 77(1), 189-201. 21. Cahn, B. R., &Polich, J. (2006) Meditation States and Traits: EEG, ERP, and Neuroimaging Studies." Psychological Bulletin, 132, 180-211. 22. Camacho, R., Roberts, R., Lazarus, N., & Kaplan, G. (1991). Physical activity and depression. American Journal o f Epidemiology, 134, 220-231. 23. Center, C. (2003). Confronting Depression and Suicide in Physicians: A Consensus Statement. The Journal o f the American Medical Association. 289 (23), 3161-3166. 24. Chambers, R., Lo, B. C., & Allen, N. B. (2008). The Impact of Intensive Mindfulness Training on Attentional Control, Cognitive Style, and Affect. Cognitive Therapy and Research, 32(3), 303-322. 25. Chandra, A. K., Sengupta, P., Goswami, H., & Sarkar, M. (2012). Excessive dietary calcium in the disruption of structural and functional status of adult male reproductive system in rat with possible mechanism. Molecular and Cellular Biochemistry, 364(1-2), 181-191. 26. Chattha, R., Nagarathna, R., Venkatram, P., & Hongasandra, N. (2008). Treating the climacteric symptoms in Indian women with an integrated approach to yoga therapy: A randomized control. Menopause, 15, 862-870. 27. Chiesa, A., Calati, R., & Serretti, A. (2011). Does Mindfulness Training Improve Cognitive Abilities? A Systematic Review of Neuropsychological Findings. Clinical Psychology Review, 31(3), 449-464. 28. Chin, R. (1995). The energy within: the science behind Eastern healing techniques. New York: Marlowe and Company. 29. Cohen, J. (1987). Immunity and behavior. Journal of Allergy and Clinical Immunology, 79.1, 2-5. 30. Cohen, S., Kessler, R., & Gordon, U. (1995). Strategies for measuring stress in studies of psychiatric and physical disorder. In: Cohen S, Kessler RC, Gordon 50

UL. Measuring Stress: A guide for Health and Social Scientist. New York, NY: Oxford University Press: 3-26. 31. Cohen, L., Warneke, C., Fouladi, R. T., Rodriguez, M. A., & Chaoul-Reich, A. (2004). Psychological Adjustment And Sleep Quality In A Randomized Trial Of The Effects Of A Tibetan Yoga Intervention In Patients With Lymphoma. Cancer, 700(10), 2253-2260. 32. Cohen, S., Janicki-Deverts, D., & Miller, G. E. (2007). Psychological Stress and Disease. The Journal o f the American Medical Association, 295(14), 1685-1687. 33. Collins, C. (1998). Yoga: Intuition, Preventive Medicine, and Treatment. Journal o f Obstetric, Gynecologic, Neonatal Nursing, 27(5), 563-568. 34. Costa, P.T& McCrae, R.R (1980). Influence of extraversion and neuroticism on subjective well-being: Happy and unhappy people. Journal o f Personality and Social Psychology, 38 (4), 668-678. 35. Craft, L. L. & D. M. Landers. (1998). The Effect of Exercise on Clinical Depression: A Meta-Analysis. Medicine & Science in Sports & Exercise 30.Supplement 117. 36. Creswell, J. D., Way, B. M., Eisenberger, N. I., & Lieberman, M. D. (2007). Neural Correlates of Dispositional Mindfulness During Affect Labeling. Psychosomatic Medicine, 69(6), 560-565. 37. Da Silva, T. L., Ravindran, L. N., & Ravindran, A. V. (2009). Yoga in the Treatment of Mood and Anxiety Disorders: A Review. Asian Journal of Psychiatry, 2(1), 6-16. 38. Davies, C., & Few, J. (1973). Effects of exercise on adrenocorticol function. European Journal of Applied Physiology, 35, 887-889. 39. Deckro, G. R., Ballinger, K. M., Hoyt, M., Wilcher, M., Dusek, J., & Myers, P. (2002). The Evaluation of a Mind/Body Intervention to Reduce Psychological Distress and Perceived Stress in College Students. Journal of American College Health, 50(6), 281-287. 40. "Depression and Anxiety." American Psychological Association. N.p., n.d. Web. 12 Mar. 2014. . 41. Desikachar, K., Bragdon, L., & Bossart, C. (2005). The yoga of healing: Exploring yoga's holistic model for health and well-being. International Journal o f Yoga, 15, 17-39. 42. Dishman, R. K. (1995). Physical Activity and Public Health: Mental Health. Quest, 47(3), 362-385. 43. DiStasio, S. A. (2008). Integrating Yoga into Cancer Care. Clinical Journal of Oncology Nursing, 72(1), 125-130. 44. Dopp, J., Miller G., Myers, H., & Fahey, J. (2000). Increased Natural Killer-Cell Mobilization and Cytotoxicity during Marital Conflict. Brain, Behavior, and Immunity, 14.1, 10-26. 45. Droste, S. K., Chandramohan, Y., Hill, L. E., Linthorst, A. C., & Reul, J. M. (2007). Voluntary Exercise Impacts on the Rat Hypothalamic-Pituitary- 51

Adrenocortical Axis Mainly at the Adrenal Level. Neuroendocrinology, 1), 26- 37. 46. Dujic, I., Valic, Z., Bakovic, D., Marinovic-Terzic, I., Eterovic, D., & Wisloff, U. (2006). Post-exercise hypotension in moderately trained athletes after maximal exercise. Medical Science Sports Exercise, 38, 318-322. 47. Duraiswamy, G., Thirthalli, J., Nagendra, H. R., & Gangadhar, B. N. (2007). Yoga Therapy as an add-on Treatment in the Management of Patients with Schizophrenia? A Randomized Controlled trial. Acta Psychiatrica Scandinavica, 116(3), 226-232. 48. Edenfield, T., & Saeed, S. (2012). An update on mindfulness meditation as a self- help treatment for anxiety and depression. Psychology Research and Behavior Management, 5, 131-141. 49. Elliott, G. R., & Eisdorfer, C. (1982). Stress and human health: analysis and implications o f research: a study. New York: Springer Publishing Co. 50. Felten, S., & Bellinger, D. (1992). Noradrenergic and peptidergic innervation of lymphoid organs. Chemical immunology, 52, 25-48. 51. Felten, S., & Felten, D. (1994). Neural-immune interaction. Progress in Brain Research, 100, 157-162. 52. Few, J. D. (1974). Effect of Exercise on the Secretion and Metabolism of Cortisol in Man. Journal o f Endocrinology, 62(2), 341-353. 53. Gibbons, J.C. (1964). Cortisol secretion rate in depressive illness. Archives if General Psychiatry, 10, 572-575. 54. Glaser, R. (1999). Stress-Induced Immunomodulation: Implications for Infectious Diseases. The Journal o f the American Medical Association, 281(24), 2268-2270. 55. Greenspan, F. S., Gardner, D. G., & Goldfien, A. (2004). Adrenal medulla. Basic & clinical endocrinology (7th ed., pp. 399-421). New York: McGraw-Hill. 56. Greenwood, B. N., & Fleshner, M. (2008). Exercise, Learned Helplessness, and the Stress-Resistant Brain. NeuroMolecular Medicine, 10(2), 81-98. 57. Gupta, N., Khera, S., Vempati, R., Sharma, R., & Bijlani, R. (2006). Effect of yoga based lifestyle intervention on state and trait anxiety. Indian Journal o f Physiology Pharmacology, 56(1), 41-47. 58. Harber, V. & Sutton, J. (1984). Endorphins and Exercise. Sports Medicine, 1(2), 154-171. 59. Hayes, P., Lucas, J., & Shi, X. (2000). Importance of post-exercise hypotension in plasma volume restoration. Acta Physiologica Scandinavica, 169(2), 115-124. 60. Heffernan, K. S., Kelly, E. E., Collier, S. R., & Femhall, B. (2006). Cardiac autonomic modulation during recovery from acute endurance versus resistance exercise. European Journal of Cardiovascular Prevention & Rehabilitation, 73(1), 80-86. 61. Henry, J. P. & Stephens, P. (1997). Stress, health, and the social environment: a sociobiologic approach to medicine. New York: Springer-Verlag. 52

62. Hermus, A. & Sweep, C. (1990). Cytokines and the hypothalamic-pituitary- adrenal axis. The Journal o f Steroid Biochemistry and Molecular Biology, 37(6), 867-871. 63. Hill, M., Hellemans, K., Verma, P., Gorzalka, B., & Weinberg, J. (2012). Neurobiology of chronic mild stress: Parallels to major depression. Neuroscience & Biobehavioral Reviews, 36(9), 2085-2117. 64. Howlett, T. A. (1987). Hormonal Responses to Exercise and Training: A Short Review. Clinical Endocrinology, 26(6), 723-742. 65. Innes, K. E., Bourguignon, C., & Taylor, A. G. (2005). Risk Indices Associated with the Insulin Resistance Syndrome, Cardiovascular Disease, and Possible Protection with Yoga: A Systematic Review. The Journal o f the American Board o f Family Medicine, 18(6), 491-519. 66. Iyengar, B. K., & Moore, D. (1989). The tree o f yoga. Boston: Shambhala. 67. Iyengar, B. K. (1997). The illustrated light on yoga (Abridged ed.). New Delhi: HarperCollins Publishers India. 68. Iyengar, BK. (2001). The path to holisitc health. London: Dorling Kindersley Publishing Inc. 69. Janal, M. (1984). Pain Sensitivity, Mood and Plasma Endocrine Levels in Man Following Long-distance Running: Effects of Naloxone. Pain, 19(1), 13-25. 70. Javnbakht, M., Kenari, R. H., & Ghasemi, M. (2009). Effects of Yoga on Depression and Anxiety of Women. Complementary Therapies in Clinical Practice, 15(2), 102-104. 71. Kabat-Zinn, J. (2003). Mindfulness-based interventions in context: past, present, and future. Clinical Psychology, 10(2), 144-156. 72. Kamei, T., Toriumi, Y., Kimura, H., & Ohno, S. (2000). Decrease in Serum Cortisol during Yoga Exercise is correlated with Alpha Wave Activation. Perceptual and Motor Skills, 90(3), 1027. 73. Kannankeril, P. J., Le, F. K., Kadish, A. H., & Goldberger, J. J. (2004). Parasympathetic Effects on Heart Rate Recovery after Exercise. Journal o f Investigative Medicine, 52(06), 394. 74. Kanojia, S., Sharma, V., Gandhi, A., Kapoor, R., Kukreja, A., & Subramanian, S. (2013). Effect of yoga on autonomic functions and psychological status during both phases of menstrual cycle in young healthy females. Journal of Clinical and Diagnostic Research, 7(10), 2133-2139. 75. Khattab, K., Khattab, A., & Ortak, J. (2007). Iyengar yoga increases cardiac parasympathetic nervous modulation among health yoga practitioners. Evidence Based Complementary Alternative Medicine, 511-517. 76. Kiecolt-Glaser, J. K., Mcguire, L., Robles, T. F., & Glaser, R. (2002). Psychoneuroimmunology: Psychological influences on immune function and health.. Journal of Consulting and Clinical Psychology, 70(3), 537-547. 77. Kimzey, S.L, Johnson, P., Ritzman, S., & Mengel, C. (1976). Hematology and immunology studies. Aviation, Space, and Environmental Medicine, 47, 383-390. 53

78. Klein, M., Greist, J., & Gurman, A. (1985). A comparative outcome study of group psychotherapy vs. exercise treatments for depression. International Journal o f Mental Health, 13, 148-177. 79. Lasater, J. (1997). The heart of pantajali. Yoga Journal, 137, 134-144. 80. Long, B. C., & Stavel, R. V. (1995). Effects of exercise training on anxiety: A meta-analysis. Journal o f Applied Sport Psychology,7(2), 167-189. 81. Maehle, G. (2007). Ashtanga yoga practice and philosophy: a comprehensive description o f the primary series o f Ashtanga yoga, following the traditional Vinyasa count, and an authentic explanation o f the Yoga Sutra o f Patanjali. Novato, Calif.: New World Library. 82. Mahajan, A., Reddy, K., & Sachdeva, U. (1999). Lipid profiles of coronary risk subjects following yogic lifestyle intervention. Indian Heart Journal, 51, 37-40. 83. Maier, S., & Watkins, L. (1998). Cytokines for psychologists: Implication of biodirectional immune-to-brain communication for understanding behavior, mood, and cognition. Psychological Review, 105, 83-107. 84. Malathi, A., & Damodaran, A. (1999). Stress due to exams in medical students- role of yoga. Indian Journal of Physiology Pharmacology, 43, 18-24. 85. Malik, M., Bigger, J., Camm, A., Kleiger, R., Malliani, A., Moss, A., & Schwartz, P. (1996). Heart rate variability: Standards of measurement, physiological interpretation, and clinical use. European Heart Journal, 17 (3), 354-381. 86. Marshall, G. (1998). Cytokine Dysregulation Associated with Exam Stress in Healthy Medical Students. Brain, Behavior, and Immunity, 12(4), 297-307. 87. Martin, C., Duclos, M., Aguerre, S., & Mormede, P. (2000). Corticotropic and serotonergic responses to acute stress with/without prior exercise training in different rat strains. Acta Physiologica Scandinavica, 168(3), 421-430. 88. Matud, P. Gender differences in stress and coping styles. Personality and Individual Differences; 2004; 37: 1401-15. 89. McCaffrey, R., Ruknui, P., Hatthakit, U., & Kasetsomboon, P. (2005). The Effects of Yoga on Hypertensive Persons in Thailand. Holistic Nursing Practice, 19(4),173-180. 90. McCall, T. Yoga is Medicine. New York: Bantam Dell a division of random house Inc, 2007. 91. McCann, I. L., & Holmes, D. S. (1984). Influence of Aerobic Exercise on Depression. Journal o f Personality and Social Psychology, 46(5), 1142-1147. 92. McDonald, D. & Hodgdon, A. (1991). The Psychological Effects o f Aerobic Fitness Training Research and Theory. New York, NY: Springer New York. 93. McEwen, B. S., & Stellar, E. (1993). Stress and the Individual: Mechanisms Leading to Disease. Archives of Internal Medicine, 753(18), 2093-2101. 94. McEwen, B. (2000). Allostasis and Allostatic Load Implications for Neuropsychopharmacology." Neuropsychopharmacology, 22 (2), 108-124. 54

95. McEwen, B. (2008). Central effects of stress hormones in health and disease: Understanding the protective and damaging effects of stress and stress mediators. European Journal o f Pharmacology, 583(2-3), 174-185. 96. McWilliams, L. A., & Asmundson, G. J. (2001). Is there a negative association between anxiety sensitivity and arousal-increasing substances and activities? Journal o f Anxiety Disorders, 15(3), 161-170. 97. Melanson, E. (2000). Resting heart rate variability in men varying in habitual physical activity. Medicine & Science in Sports & Exercise, 32(11), 1894-1901. 98. Meyer, R., Kroner-Herwig, B., & Sporkel, H. (1990). The effect of exercise and induced expectations on visceral perception in asthmatic patients. Journal o f Psychosomatic Research, 34(4), 455-460. 99. Myers, E. & Pottruff, R. (1997). Yoga & you: energizing and relaxing yoga for new and experienced students. Boston, Mass: Shambhala. 100. Michalsen, A., Grossman, P., Acil, A., Langhorst, J., & Ludtke, R. (2005). Rapid stress reduction and anxiolysis among distressed women as a consequence of a three month intensive yoga program. Medical Science Monitor, 11, 555-561. 101. Miller, G., Stetler, C„ Carney, R„ Freedland, K., & Banks, W. (2002). Clinical depression and inflammatory risk markers for coronary heart disease. The American Journal o f Cardiology, 90(12), 1279-1283. 102. Moadel, A., Shaw, C., Wylie-Rossett, J., & Harris, M. (2007). Randomized control trial of yoga among a multiethnic sample of breast cancer patients. Journal o f Clinical Oncology, 25, 1-9. 103. Moses, J., Steptoe, A., Mathews, A., & Edwards, S. (1989). The Effects of Exercise Training on Mental Well-being in the Normal Population: A Controlled Trial. Journal of Psychosomatic Research, 35(1), 47-61. 104. Naquin, M., & Gilbert, G. (1996). College Students' smoking behavior, perceived stress, and coping styles. Journal o f Drug Education, 26(4), 367-376. 105. Nolen-Hoeksema, S. (1987). Sex differences in unipolar depression: Evidence and theory. Psychology Bull, 101, 259-82. 106. Nolten, W., Goldstein, D., Lindstrom, M., Mckenna, M., Carlson, I., Trump, D., et al. (1993). Effects of Cytokines on the Pituitary-Adrenal Axis in Cancer Patients. Journal o f Interferon Research, 13(5), 349-357. 107. North, T. C., McCullagh, P., & Tran, Z. V. (1990). Effect of Exercise on Depression. Exercise and Sport Sciences Reviews, 18(\), 379-416. 108. O'Leary, A. (1990). Stress, emotion, and human immune function. Psychological Bulletin, 108(3), 363-382. 109. Orizio, C., Perini, R., Comand, A., Castellano, M., Beschi, M., & Veicsteinas, A. (1988). Plasma catecholamines and heart rate at the beginning of muscular exercise in man. European Journal o f Applied Physiology and Occupational Physiology, 57(5), 644-651. 55

110. Paffenbarger, R. & Hyde, R. (1988). Exercise adherence, coronary heart disease and longevity. Exercise adherence: Its impact on public health. Champaign, IL: Human Kinetics Book, 41-73. 111. Palmblad, J., Cantell, K., Strander, H., Froberg, J., Karlsson, C.G., Levi, L., Granstrom, M., &Unger, P. (1976). Stressor exposure and immunological response in man: Interferon-producing capacity and phagocytosis. Journal o f Psychosomatic Research, 20(3), 193-199. 112. Papier K, Ahmed F., Lee P., Wiseman, J. (2015). Stress and dietary behavior among first-year university students in Australia: Sex differences. Nutrition, 31, 324-30. 113. Payan, D. G., Hess, C. A., & Goetzl, E. J. (1984). Inhibition by somatostatin of the proliferation of T-lymphocytes and Molt-4 lymphoblasts. Cellular Immunology, 84(2), 433-438. 114. Perini, R., Orizio, C., Baselli, G., Cerutti, S., & Veicsteinas, A. (1990). The influence of exercise intensity on the power spectrum of heart rate variability. European Journal of Applied Physiology and Occupational Physiology, 61(1-2), 143-148. 115. Peronnet, F., Cleroux, J., & Perrault, H. (1981). Plasma norepinephrine response to exercise before and after training in humans. European Journal o f Applied Physiology, 51, 812-815. 116. Petruzzello, S. J., Landers, D. M., Hatfield, B. D., Kubitz, K. A., & Salazar, W. (1991). A Meta-Analysis on the Anxiety-Reducing effects of Acute and Chronic Exercise. Sports Medicine, 77(3), 143-182. 117. Pilkington, K., Kirkwood, G., Rampes, H., & Richardson, J. (2005). Yoga for Depression: The Research Evidence. Journal o f Affective Disorders, 59(1-3), 13- 24. 118. Queiroz, A. C., Gagliardi, J. F., Forjaz, C. L., & Rezk, C. C. (2009). Clinic and Ambulatory Blood Pressure Responses after Resistance Exercise. Journal o f Strength and Conditioning Research, 23(2), 571-578. 119. Reiss, S. & Bootzin, R. (1985). Theoretical issues in behavior therapy. Orlando: Academic Press. 120. Rezk, C. C., Marrache, R. C., Tinucci, T., Mion, D., & Forjaz, C. L. (2006). Post­ resistance exercise hypotension, hemodynamics, and heart rate variability: influence of exercise intensity. European Journal of Applied Physiology, 95(1), 105-112. 121. Riley, D. (2004). Hatha yoga and the treatment of illness. Alternative Therapeutic Health Medicine, 10(2), 20-21. 122. Rocha, K., Riberio, A., Rocha, K., Sousa, M., Albuquerque, F., Riberio, S., & Silva, R. (2012). Improvement in physiological and psychological parameters after 6 months of yoga practice. Consciousness and Cognition, 21, 843-850. 56

123. Ross, A., & Thomas, S. (2010). The Health Benefits of Yoga and Exercise: A Review of Comparison Studies. The Journal o f Alternative and Complementary Medicine, 16( 1), 3-12. 124. Roth, D., & Holmes, D. (1987). Influence of aerobic exercise training and relaxation on physical and psychological health following stressful life events. Psychosomatic Medicine, 49, 355-365. 125. Russell, V. (2014). The interaction between stress and exercise, and its impact on brain function. Metabolic Brain Disease (pp. 1-17). New York: Springer Science + Business Media. 126. Russo-Marie, F. (1992). Macrophages and the glucocorticoids. Journal o f Neuroimmunology, 40(2-3), 281-286. 127. Sadava, S. W., & Pak, A. W. (1993). Stress-related problem drinking and alcohol problems: A longitudinal study and extension of Marlatt's model. Canadian Journal of Behavioural Science/Revue canadienne des Sciences du comportement, 25(3), 446-464. 128. Salmon, P. (2001). Effects of physical exercise on anxiety, depression, and sensitivity to stress: A unifying theory. Clinical Psychology Review, 27(1), 33-61. 129. Sanders, V., & Kohm, A. (2002). Sympathetic nervous system interaction with the immune system. International Review Neurobiology, 52, 17-41. 130. Saper, R., Eisenburg, D., & Davis, R. (2004). Prevalence and patterns of adult yoga use in the United States: results of a national survey. Alternative Therapeutic Health Medicine, 10, 44-49. 131. Schiffmann, E. (1996). Yoga: the spirit and practice o f moving into stillness. New York: Pocket Books. 132. Schulkin, Jay. (2004). Allostasis, homeostasis and the costs o f physiological adaptation. New York: Cambridge University Press. 133. Segerstrom, S. C., & Miller, G. E. (2004). Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry. Psychological Bulletin, 130(4), 601-630. 134. Selvamurthy, W., Sridharan, K., Ray, U., & Tiwary, R. (1998). A new physiological approach to control essential hypertension. Indian Journal o f Physiology Pharmacology, 42, 205-213. 135. Sengupta, P. (2012). Health impacts of yoga and pranayama: A state-of-the-art review. International Journal of Preventative Medicine, 3(1), 444-458. 136. Shapiro, S., Oman, D., Thoresen, C., Plante, T., & Flinders, T. (2008). Cultivating Mindfulness: Effects on Well-Being. Journal o f Clinical Psychology, 64(1), 840- 862. 137. Smith, C., Hancock, H., Blake-Mortimer, J., & Ekert, K. (2007). A randomized comparative trial of yoga and relaxation to reduce stress and anxiety. Complementary Therapies in Medicine, 15, 77-83. 57

138. Stephens, T. (1988). Physical Activity and Mental Health in the United States and Canada: Evidence from Four Population Surveys. Preventive Medicine, 77(1), 35- 47. 139. Steptoe, A. (1997). Leisure-Time Physical Exercise: Prevalence, Attitudinal Correlates, and Behavioral Correlates among Young Europeans from 21 Countries. Preventive Medicine, 26(6), 845-854. 140. Steptoe, A., Kimbell, J., & Basford, P. (1998). Exercise and the experience and appraisal of daily stressors. Journal of Behavior Medicine, 21, 363-374. 141. Stewart, A., Hays, R., Wells, K., Rogers, W., Spritzer, K., & Greenfield, S. (1994). Long-term Functioning and Well-being Outcomes Associated with Physical Activity and Exercise in Patients with Chronic Conditions in the Medical Outcomes Study. Journal o f Clinical Epidemiology, 47(7), 719-730. 142. Stroud L., Salovey, P., & Epel, E. (2002). Sex differences in stress response: Special rejections versus achievement stress. Biology Psychiatry, 52, 318-27. 143. Teixeira, L., Ritti-Dias, R. M., Tinucci, T., Junior, D. M., & Forjaz, C. L. (2011). Post-concurrent exercise hemodynamics and cardiac autonomic modulation. European Journal of Applied Physiology, 777(9), 2069-2078. 144. Thoren, P., Hoffman, P., & Seals, D. (1990). Endorphins and exercise. Medicine and Science in Sports and Exercise, 22, 417-428. 145. Tran, M., Holly, R., Lashbrook, J., & Amsterdam, E. (2001). Effects of Hatha Yoga Practice on the Health-Related Aspects of Physical Fitness. Preventive Cardiology, 4(4), 165-170. 146. Turnbull, A., & Rivier, C. (1999). Regulation of the hypothalamic-pituitary- adrenal axis by cytokines: Actions and mechanisms of action. Physiology Review, 79, 1-71. 147. "Understanding Anxiety and Depression." Anxiety and Depression Association of America, ADAA. N.p., n.d. Web. 12 Mar. 2014. . 148. Vale, W., Spiess, J., Rivier, C., & Rivier, J. (1981). Characterization of a 41- residue Ovine Hypothalamic Peptide that Stimulates Secretion of Corticotropin and Beta-endorphin."Science, 213(4514), 1394-1397. 149. Vivekananda, R. (2007). Yoga (34th Impression). Advaita Asrama. 150. Watanabe, T., Morimoto, K., & Sakata,Y. (1991). The effect of chronic exercise on the pituitary-adrenocortical response in conscious rats. European Journal of Applied Physiology, 439, 691-699. 151. West, J., Otte, C., Geher, K., Johnson, J., & Mohr, D. C. (2004). Effects of Hatha Yoga and African Dance on Perceived Stress, Affect, and Salivary Cortisol. Annals o f Behavioral Medicine, 28(2), 114-118. 152. Wiedenfeld, S., O'leary, A., Bandura, A., & Brown, S. (1990). Impact of perceived self-efficacy in coping with stressors on components of the immune system. Journal o f Personality and Social Psychology, 59(5), 1082-1094. 58

153. Williams, K., Steinberg, L., & Petronis, J. (2003). Therapeutic application if iyengar yoga for healing chronic low back pain. International Journal o f Yoga Therapy, 13,55-67. 154. Wong, J., Cheung, E., Chan, K., Ma, K., & Tan SW. (2006). Web-based survey of depression, anxiety, and stress in first-year tertiary education students in Hong Kong. Aust NZJPsychiatry,40, 777-82. 155. Woodyard, C. (2011). Exploring the therapeutic effects of yoga and its ability to increase quality of life. International Journal o f Yoga, 4(2), 49. 156. Yeung, R. (1996). The Acute Effects of Exercise on Mood State. Journal o f Psychosomatic Research, 40(2), 123-141.