Relationship of Body Composition, Strength, and Asymmetry to Lower Extremity Physical Function in Women: Impact of Age and Physical Activity Level
Misic, Mark Mathew
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https://hdl.handle.net/2142/86384
Description
Title
Relationship of Body Composition, Strength, and Asymmetry to Lower Extremity Physical Function in Women: Impact of Age and Physical Activity Level
Author(s)
Misic, Mark Mathew
Issue Date
2007
Doctoral Committee Chair(s)
Evans, Ellen M.
Department of Study
Kinesiology and Community Health
Discipline
Kinesiology and Community Health
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Health Sciences, Recreation
Language
eng
Abstract
Preserving independence in the aging population has become a public health priority; therefore, understanding factors that contribute to physical declines is critical. This study explored the relationships among body composition, strength, and lower extremity physical function (LEPF) in women varying in physical activity and age. Lower extremity asymmetries in strength and muscle mass and the relative contributions of intrinsic electrical, measured by electromyography (EMG), and mechanical, measured by mechanomyography (MMG), properties of muscle function were explored as possible determinants of declines in LEPF across the adult lifespan. One hundred four women were tested (mean +/- standard deviation; age 46.9 +/- 19.9 years, range = 20--83 years; body mass index = 23.9 +/- 4.00 kg/m2; body fat 30.6 +/- 6.9%; average daily steps 9891 +/- 4005). Body composition, including mineral free lean mass (MFLM), was measured using dual energy x-ray absorptiometry. Strength was assessed using an isokinetic dynamometer. LEPF was assessed using a 7-meter walk with and without an obstacle, an up-go speed/agility test, and a lower extremity reach test where the participant stood on one leg and reach maximally with the opposite leg in several directions. The results revealed that strength, MFLM, muscle quality, and physical activity declined; however, declines were often not significant until over 60 years of age. Body fatness increased with age. Age was the best predictor of LEPF overall; however, when age was controlled for, body fatness was the best predictor. When analyzing the data by age groups, the young women were less fat and LEPF was more strongly related to MFLM whereas the women over 40 years of age were fatter and LEPF was more closely related to fatness than MFLM. Leg asymmetries in composition or function explained a very small amount of the variability in LEPF. EMG did not differ significantly across the lifespan but MMG was significantly different among young, middle-aged, and older women. This study offers insights into the interactions between physical activity, body composition and LEPF in women across the adult lifespan to aid the design of appropriate interventions to preserve independence in late life.
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