Experimental Section

Muscle Quality, Aerobic Fitness and Fat Mass Predict Lower-Extremity Physical Function in Community-Dwelling Older Adults
Mark M. Misic^a, Karl S. Rosengren^{a, c}, Jeffrey A. Woods^{a, b}, Ellen M. Evans<sup>a, b

a</sup>Department of Kinesiology and Community Health,
^bDivision of Nutritional Sciences, and
^cDepartment of Psychology, University of Illinois at Urbana-Champaign, Urbana, Ill., USA

Address of Corresponding Author

Gerontology 2007;53:260-266 (DOI: 10.1159/000101826)

  Key Words

• Body composition
• Physical fitness
• Muscle strength

  Abstract

Background: Muscle mass, strength and fitness play a role in lower-extremity physical function (LEPF) in older adults; however, the relationships remain inadequately characterized. Objective: This study aimed to examine the relationships between leg mineral free lean mass (MFLM_LEG), leg muscle quality (leg strength normalized for MFLM_LEG), adiposity, aerobic fitness and LEPF in community-dwelling healthy elderly subjects. Methods: Fifty-five older adults (69.3 ± 5.5 years, 36 females, 19 males) were assessed for leg strength using an isokinetic dynamometer, body composition by dual energy X-ray absorptiometry and aerobic fitness via a treadmill maximal oxygen consumption test. LEPF was assessed using computerized dynamic posturography and stair ascent/descent, a timed up-and-go task and a 7-meter walk with and without an obstacle. Results: Muscle strength, muscle quality and aerobic fitness were similarly correlated with static LEPF tests (r range 0.27-0.40, p < 0.05); however, the strength of the independent predictors was not robust with explained variance ranging from 9 to 16%. Muscle quality was the strongest correlate of all dynamic LEPF tests (r range 0.54-0.65, p < 0.001). Using stepwise linear regression analysis, muscle quality was the strongest independent predictor of dynamic physical function explaining 29-42% of the variance (p < 0.001), whereas aerobic fitness or body fat mass explained 5-6% of the variance (p < 0.05) depending on performance measure. Conclusions: Muscle quality is the most important predictor, and aerobic fitness and fat mass are secondary predictors of LEPF in community-dwelling older adults. These findings support the importance of exercise, especially strength training, for optimal body composition, and maintenance of strength and physical function in older adults.

Copyright © 2007 S. Karger AG, Basel

  Author Contacts

Ellen M. Evans
Department of Kinesiology and Community Health
University of Illinois at Urbana-Champaign
215 Freer Hall, 906 S Goodwin MC-052, Urbana, IL 61801 (USA)
Tel. +1 217 333 6768, Fax +1 217 244 7322, E-Mail elevans@uiuc.edu

  Article Information

Received: September 21, 2006
Accepted: March 3, 2007
Published online: April 18, 2007
Number of Print Pages : 7
Number of Figures : 0, Number of Tables : 4, Number of References : 33