University of Massachusetts Amherst ScholarWorks@UMass Amherst Open Access Dissertations 9-2013 Recovery From Muscle Fatigue in Young and Older Adults: Implications for Physical Function Stephen A. Foulis University of Massachusetts Amherst, [email protected] Follow this and additional works at: https://scholarworks.umass.edu/open_access_dissertations Part of the Kinesiology Commons Recommended Citation Foulis, Stephen A., "Recovery From Muscle Fatigue in Young and Older Adults: Implications for Physical Function" (2013). Open Access Dissertations. 792. https://doi.org/10.7275/bkqg-bt54 https://scholarworks.umass.edu/open_access_dissertations/792 This Open Access Dissertation is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Open Access Dissertations by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. RECOVERY FROM MUSCLE FATIGUE IN YOUNG AND OLDER ADULTS: IMPLICATIONS FOR PHYSICAL FUNCTION A Dissertation Presented by Stephen A. Foulis Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY September 2013 Department of Kinesiology © Copyright by Stephen A. Foulis 2013 All Rights Reserved RECOVERY FROM MUSCLE FATIGUE IN YOUNG AND OLDER ADULTS: IMPLICATIONS FOR PHYSICAL FUNCTION A Dissertation Presented by Stephen A. Foulis Approved as to style and content by: ____________________________________ Jane A. Kent-Braun, Chair ____________________________________ Richard van Emmerik, Member ____________________________________ Edward Debold, Member ____________________________________ John Buonaccorsi, Member __________________________________________ Patty Freedson Chair, Department of Kinesiology DEDICATION To my father, John Foulis. ACKNOWLEDGMENTS To paraphrase Yogi Berra, I’d like to thank all the people who made this day necessary. First and foremost, I’d like to thank Anne Tonson, Jessica Fay, Terri O’Brien, Jacob DeBlois, and all of the undergrads from the Muscle Physiology Lab for all of their assistance on this project. Between recruiting participants, marathon data collections, reviewing documents, and overall keeping me sane, I couldn’t have done this without you guys. Thanks also to the members of the Motor Control Lab, especially Stephanie Jones, Luis Rosado, and Mike Busa for all of the help with Study 2. And to my committee, as well as all of the graduate students, faculty and staff of the Kinesiology department, thanks for all the help, whether it be intellectually, physically, or emotionally. I would be remiss if I didn’t thank all of the Muscle Physiology Lab alumni who helped me get through the last 8 years: Damien Callahan, Ryan Larsen, Anita Christie, Bryce Jones, Linda Chung, Mike Tevald, and Danielle Wigmore. A special thanks to Ian Lanza for convincing me that this was a great lab to work in and mentoring my early days. And thanks especially to my adviser, Jane Kent-Braun. You took a chance allowing this junior pre-med/biology undergrad to do an honors project in your lab, and then took another chance by inviting him to stay for grad school. You’ve shown me the joy of research and will continue to have a lasting influence on the direction of my life. I also wish to thank my family. My mother, brothers, and their families have supported me every step of the way, and given me the strength to persevere. Last, but not least (perhaps even most of all), my wife Stacy. You’ve always been there to share my good days and cheer me up on the bad ones. I can’t possibly thank you enough for all the love, support, and assistance you’ve provided along the way. v ABSTRACT RECOVERY FROM MUSCLE FATIGUE IN YOUNG AND OLDER ADULTS: IMPLICATIONS FOR PHYSICAL FUNCTION SEPTEMBER 2013 STEPHEN A. FOULIS, B.S., UNIVERSITY OF MASSACHUSETTS AMHERST M.S., UNIVERSITY OF MASSACHUSETTS AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Jane A. Kent-Braun As adults age, skeletal muscles become smaller and weaker, which can ultimately lead to declines in physical function and disability. In general, older adults produce less isometric force and dynamic power than younger adults. The effects of this weakness are amplified following a series of muscle contractions that result in muscle fatigue. Since daily routines consist of repeated series of activity followed by rest, it is important to understand how muscle recovers from fatigue. In particular, muscle power has been shown to be related to physical function and balance. Thus, understanding the process of recovery from muscle fatigue will help in preventing declines in physical function in older adults. This dissertation consisted of two studies designed to understand how muscle recover following fatigue and the implications of that recovery on physical function. Study one examined recovery from muscle fatigue following a constrained task. Young and older adults were fatigued to a similar degree using a dynamometer, and recovery of power at 4 velocities, central activation, pre-motor signaling, neural efficiency and contractile properties were recorded over an hour. To evaluate the functional implications of the recovery, ratings of perceived exertion were collected and vi the amount of fatigue following a second fatigue bout was also recorded. The second study associated changes in physical function and balance with power following an ecologically-relevant fatiguing exercise. Following a 30 minute treadmill walk, chair rise time and balance were measured during the period of recovery from this task. As a result of fatigue, we saw increased power loss at high-velocities that did not recover over the course of an hour in older adults. This finding was concurrent with other velocity specific changes in rates of force development, muscle acceleration, and pre-motor neural signaling. Functionally, we saw an increased in perceived effort during contraction in older adults, and an increased fatigue during a second fatigue bout. While chair rise didn’t differ as a group with fatigue, there was a significant relationship with loss of high- velocity power and change in chair rise time over the hour recovery period. Balance declined immediate post-fatigue but appeared to recover to a point of greater stability over an hour. This dissertation provides novel insight about alterations in the recovery process following an acute bout of muscle fatigue, and ultimately provides data that may be useful for developing strategies to prevent disability in older adults. vii PREFACE Chapters 1 through 3 include the dissertation proposal as submitted to the Graduate School in March 2012. During the IRB review process, the maximum vertical jump was removed from Study 2. Chapter 4 and 5 correspond with Study 1 and 2, respectively. In accordance with the wishes of the committee, these chapters are formatted as manuscripts to be submitted for peer-review. viii TABLE OF CONTENTS Page ACKNOWLEDGMENTS .................................................................................................. v ABSTRACT ....................................................................................................................... vi PREFACE ........................................................................................................................ viii LIST OF TABLES ............................................................................................................ xii LIST OF FIGURES ......................................................................................................... xiii GLOSSARY ..................................................................................................................... xv CHAPTER 1: INTRODUCTION .......................................................................................................... 1 Significance of Dissertation .................................................................................... 5 Study 1: Mechanisms of Recovery from Neuromuscular Fatigue in Young and Older Women .............................................................................................. 6 Study 2: Recovery of Physical Function from Neuromuscular Fatigue in Older Women ........................................................................................................ 8 2: LITERATURE REVIEW ............................................................................................. 10 The Aged Neuromuscular System ........................................................................ 10 Muscle Size and Strength .......................................................................... 10 Alterations in Neural Properties ................................................................ 14 Alterations in Physical Function, Balance, and Symptomatic Fatigue ..... 16 Muscle Fatigue ...................................................................................................... 18 Isometric Force and Dynamic Power ........................................................ 18 Mechanisms of Muscle Fatigue ................................................................ 19 Consequences of Muscle Fatigue.............................................................. 23 Recovery from Muscle Fatigue ................................................................. 24 Aging and Muscle Fatigue .................................................................................... 27 Fatigue