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Procedia Social and Behavioral Sciences 15 (2011) 1630–1634

WCES-2011 The effect of 8-weeks aerobic exercise training on serum LEPTIN in un-trained females a* Masoumeh Azizi 1

aDepartment of Sport Science. Islamic Azad University, Abadan Branch. Abadan. Iran

Abstract

Objective No doubt, can cause for some metabolic syndromes, type 2 , , other and osteoarthritis. Given the undeniable role of sport in general health, the aim of this study was to assay the effect of regular exercise on serum level of Leptin in un-trained female. Materials and Methods: 24 untrained-female subjects randomly divided in two groups (Control group and Experimental group). Blood samples were taken 48 h before starting the aerobic training program. Then, experimental group performed the aerobic training program included running with 65-85% of individual maximum heart rate on treadmill for 3 session per week, 30 minute per session and 8 consecutive weeks. Then another blood sample was taken following the training period. Serum levels of leptin of all subjects before and after the training period were measured using standard biochemical methods from all the subjects in both groups again. Results: Our results showed that the aerobic training resulted in a significant decrease in leptin serum in experimental group but no significant difference was seen in leptin serum in control group. Conclusion: The result showed that regular and light aerobic exercise could decrease leptin levels in un-trained female. So, decreases in serum leptin may be one mechanism by which weight loss improves physical function. © 2011 Published by Elsevier Ltd.

Keywords: Exercise training, Leptin, un-trained female.

1. Introduction

Obesity can be titled as the "New World Syndrome" that affecting not only the developed but also developing countries (Ren 2004). It associated with health problems has been rose in all age groups in the world. According to the recent studies, It is estimated that obesity currently affects 25% of children in the United States (Nammi et al 2004). It is also responsible for some metabolic syndromes, type 2 diabetes, hypertension, other cardiovascular disease and osteoarthritis (Nammi et al 2004, Tamer et al 2002]. The pathogenesis of obesity is multi-factorial such as genetics, high fat , lack of exercise and stress that cause obesity and overweight (.Blaak 2000) Numerous advance studies in understanding the frequency of genes that are involved in regulation of body weight have been done, but since 1994 following the discovery of the ob gene that product leptin, these studies have progressed dramatically (Zhang et al 1994). Leptin is single-chain proto hormone with a molecular mass of 16 kDa that is thought to play a key role in the regulation of body weight (Friedman and Halaas 1998). Leptin acts on the central nervous system, in particular the hypothalamic nuclei (Webber 2003). Neurons in the arcuate, ventromedial, and dorsomedial hypothalamic nuclei that are regulation of energy balance (Ahima 2000). Adipose tissue is the major source of leptin expression; however, other sites have been identified, including skeletal muscle, liver, stomach, heart, mammary epithelium, the placenta, and the brain (Bouassida et al 2006). The findings suggest after leptin secretion by adipose tissue, the leptin receptors (with long and short isoforms) are expressed in a variety of tissues including the hypothalamic nuclei (Baratta 2002). Neurons in the arcuate,

* Masoumeh Azizi, Tel.: +98-631-4460-119. E-mail address: [email protected]

1877–0428 © 2011 Published by Elsevier Ltd. doi:10.1016/j.sbspro.2011.03.343 Masoumeh Azizi et al. / Procedia Social and Behavioral Sciences 15 (2011) 1630–1634 1631 ventromedial and dorsomedial hypothalamic nuclei that are sensitive to leptin, express neuropeptidis/ neurotransmitters that are associated with central regulation of appetite, food intake, energy expenditure, and as a consequence body fat and body weight(Ahima 2000 & Hassink et al 1996]. Based on this claim that leptin's actions is on energy balance (Ishii et al 2001), and whereof exercise is a effective way to reduce obesity(fat mass), it is reasonable to speculate that leptin hormone plays a role in predicting weight change in a population, although results from previous studies in this area are conflicting. For example, in young non diabetic, Pima Indians, those that gained weight over a 3-year period, had lower plasma leptin levels at baseline than those who maintained their weight (Robert et al 2002). This indicates a relative deficiency of a satiety signal from adipose tissue. In contrast, other studies in obese children and young men and women show that low plasma leptin levels are predictive of weight loss, suggesting a greater sensitivity to circulating serum leptin (Kohrt et al 1996, Torgerson et al 1999, Verdich et al 2001). Elias et al. stated a decline in leptin concentrations in males (age,18-55) after a graded treadmill exercise test plasma leptin is detectable after 10 months of training to exhaustion (Ravussin et al 1997). Merino et al. reported that after 3 weeks of a military training, leptin concentrations were decreased. The fat mass in this study was not measured, but the body weight remained stable. Bouassida et al indicate that plasma leptin concentration is not sensitive to acute short or prolonged exercise (under 800-kcal of energy expenditure) in elite volleyball players. In addition, plasma leptin concentration was lower in volleyball/anaerobically trained athletes with respect to untrained subjects. It appears that leptin is more sensitive to energy expenditure than hormonal or metabolic modifications induced by acute exercise (hypo insulinemia, hyper secretion of growth hormone and hyper lactatemia) in anaerobically trained athletes as in aerobically trained athletes as shown by past studies (Bouassida(b) et al 2009]. Unal et al (2005) measured leptin concentrations in trained young male athletes and in healthy sedentary subjects. They stated a significant lower leptin after exercise and concluded that regular exercise, by reducing fat percentage, suppresses serum leptin levels. Frank et al (2005) reported that regular, moderate exercise decreases fasting insulin and leptin concentrations in overweight / obese postmenopausal women and that the adoption of regular/ moderate intensity exercise may be particularly useful among post menopausal women who gain mass over time. Some researchers have reported that acute aerobic exercise does not generate decreases on leptin concentration (Rahmani Nia et al 2009). Houmard et al (2000) reported short-term aerobic training (60 minutes at 75% of VO2max during 7 successive days) does not modify leptin concentrations in healthy young and older males. Although the training improved insulin sensitivity, leptin concentration was not affected. In other study, Kraemer et al (2002) measured resting and post maximal exercise leptin concentration of adolescent female runners, over the course of a short track season. Resting leptin levels were not changed over the 7 weeks, nor were the acute responses to intense exercise despite a significant reduction in skin folds (Houmard et al 2000). Zoladz et al (2005) measured the variation of leptin in 8 men following two incremental exercises. The maximal incremental exercise was performed in the fed state however the sub-maximal incremental exercise test up to 150 W was performed in a fasted state; the authors noted no significant differences in leptin concentrations. So, it could be said generally short-term exercise that generated energy expenditure lower than 800 Kcal do not modify the concentration of leptin (Kraemer (a) et al 2001). Therefore, the specific aim of the present study was to investigate whether 8-weeks aerobic exercise training would modulate serum leptin in un-trained females.

2. Materials and Methods

2.1. Subjects Twenty four healthy-untrained females (age 29.8 ± 4.1 yr, height 161 ± 7 cm, body weight 65.6 ± 5.2 kg) volunteered to participate in this investigation. Before initiation of the study, subjects were asked to sign a written, informed consent. All subjects completed a medical questionnaire to ensure that they were not taking any medication, were free of cardiac, respiratory, renal, or metabolic diseases, and were not using steroids. 2.1.1. Methods All subjects randomly divided into2 equal groups: Group 1: Control group (n=12), Group 2: Experimental group (n=12). 48 h before starting the aerobic training program Weight, Height, Blood samples and BMI were taken from all the subjects using proper devices/methods: weight by scale, height by measuring-tape, body mass index (BMI) by the ratio of weight square root of height. Then, experimental group performed the aerobic training program included running with 65-85% of individual maximum heart rate on treadmill for 3 sessions per week, 30 minute per session for 8 consecutive weeks. Then another Weight, Blood sample and BMI was taken in the of the training 1632 Masoumeh Azizi et al. / Procedia Social and Behavioral Sciences 15 (2011) 1630–1634

period. Serum levels of leptin of all subjects before and after the training period were measured using standard biochemical methods from all the subjects in both groups again.

2.1.1.1. Statistical analysis All values are reported as Means ±SE. Differences between exercise-induced changes in plasma leptin concentrations and BMI before and after exercise protocol were evaluated using a Studentƍs t-test for paired samples. A P-value < 0.05 was considered to be statistically significant.

3. Results Mean and standard deviation of variables including weight, BMI and leptin level for each subject of control group (Post-test and Pre-test) are shown in table.1.and for each subject of experimental group (Post-test and Pre-test) in table.2.

Table 1. Control group measures for body weight, BMI, and leptin

Control Group Pre-Test Mean Post-Test Mean Weight(Kg) 66.66±5.99 67.01±5.42 BMI(Kg.m2) 25.72±3.96 25.81±2.95 Leptin Hormone(Ng.ml) 24.72±15.63 27.01±14.14

Table 2. Experimental group measures for body weight, BMI, and leptin

Experimental Group Pre-Test Mean Post-Test Mean Weight(Kg) 62.78±8.92 57.50±5.42 BMI(Kg.m2) 24.72±3.96 22.41±1.95 Leptin Hormone(Ng.ml) 28.42±12.78 17.10±10.54

The changes in the control group were not significant (p>0.05).Table 2 demonstrates the mean changes in leptin level of plasma (before and after 8 weeks aerobic training). All participants who carried out the aerobic training lost some weight. In this group, a significant relationship was observed between the decrease in weight and body mass index (BMI) [p=0.001 and p=0.004, respectively]. And mean Leptin (p=0.001) levels decreased. So, this research showed that there was a significant relationship between the decrease in leptin , weight and body mass index following aerobic training.

4. Discussion

Research evidence shows that the low mobility is a most important factor to be a person obese and overweight, and implementing a training program can be significant changes in weight and body composition created. More ever, many studies have shown, Leptin is an adipocyte -secreted hormone that seems to play an important role in the body weight regulation in humans (Bouassida(b) et al 2009). Based on these finding we decided to do this project. The result of present study demonstrate that moderate-intensity exercise for 8 weeks and three session per week, significant decrease in body weight, BMI and serum leptin level. However, further studies are necessary to clarify this relationship p. Our data consistent with those reported exercise training resulted in decreased leptin concentration (Nammi et al 2004 & Weltman et al 2000). However, these decreases were related mainly to negative energy balance and/or to loss of adipose tissue, and suggested that exercise training does not have an independent effect on circulating leptin. Kohrt et al (1996) for example, who found that long-term exercise training, can decrease plasma leptin concentrations in older women by reducing fat mass. Also, Ishii et al (2001) proved that serum leptin level decreased after 6 weeks of aerobic training exercise in type 2 diabetics’ patients, but there was not any relationship between the decrease in leptin concentration and changes in adipose tissue. Reseland et al (2001) Masoumeh Azizi et al. / Procedia Social and Behavioral Sciences 15 (2011) 1630–1634 1633 concluded that long-term diet and exercise may have direct effects on plasma leptin concentration beyond the effect expected due to changes in fat mass. The results of this study contrast to the results of Weltman et al 2000, who recently reported that 30 min of exercise at various intensities and caloric expenditure (from 150 ± 11 to 529 ± 45 kcals) in 7 healthy young men did not cause modifications in leptin levels during the exercise and during the recovery (3.5 hours). Zoladz et al (2005) and Kraemer et al (2002) also reported no significant changes in leptin concentrations following short-term exercises. There are several factors that can explain this modification of the response of leptin to muscular exercise. That is probably related to the intensity and the duration of the exercise, the nutritional status of the subject, the circadian rhythm of leptin, the hour of blood sampling and the caloric imbalance imposed by the exercise. But, what is known is that leptin act through changes in ob gene expression in adipose tissue. Changes in leptin correlated with the changes in body weight. Some researchers believe that aerobic exercise is the best way to reduce body fat and ultimately in the regulation of leptin level. They are trying to be able to leptin treatment by way easier to find for the treatment of obesity.

5. Conclusion

In summary, the result of present study showed that regular and light aerobic exercise could decrease leptin levels in un-trained females. So, decreases in serum leptin may be one mechanism by which weight loss improves physical function. And finally, it seems that more investigations is need to better define the relation of adiposity in both gender to leptin responses and adaptations to exercise.

Acknowledgement

This study was supported by a grant from Islamic Azad University Abadan Branch (Iran) and this paper was taken from the project titled “The Effect of 8-Weeks Aerobic Exercise on Serum Leptin and some Risk Factors of Coronary Heart Disease in un-trained Females" . We would like to thank a very dedicated group of subjects and their coach who made this project possible.

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