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ARS Home » Northeast Area » Boston, Massachusetts » Jean Mayer Human Nutrition Research Center On Aging » Research » Publications at this Location » Publication #226824

Title: Lower Extremity Muscle Mass Predicts Functional Performance in Mobility-Limited Elders

Author
item REID, KIERAN - HNRCA AT TUFTS UNIVERSITY
item NAUMOVA, ELENA - TUFTS UNIVERSITY
item CARABELLO, ROBERT - HNRCA AT TUFTS UNIVERSITY
item PHILLIPS, EDWARD - SPAULDING REHAB HOSPITAL
item Fielding, Roger

Submitted to: Journal of Nutrition Health and Aging
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2008
Publication Date: 8/1/2008
Citation: Reid, K.F., Naumova, E.N., Carabello, R.J., Phillips, E., Fielding, R. 2008. Lower Extremity Muscle Mass Predicts Functional Performance in Mobility-Limited Elders. Journal of Nutrition Health and Aging. 12(7):493-498.

Interpretive Summary: As life expectancy of older adults continues to increase, understanding the factors that lead to functional decline is now of major public health importance. This study investigated the role of physical activity, leg strength, bone density, and body composition and their subsequent influence on functional performance in mobility-impaired older adults. Fifty-seven subjects with moderate to severe functional limitations were studied. The study revealed that the amount of muscle tissue and strength in the legs were independently associated with the level of mobility impairment. In particular, the study demonstrated that there was a strong association between low muscle tissue and the severity of physical impairment. These findings are important because muscle mass and strength deficits are potentially reversible, and imply that preserving both muscle mass and strength could serve to maintain mobility and functioning in later life. We suggest that future studies should explore the role of diet, exercise, lifestyle or possibly pharmacologic interventions designed to increase muscle tissue, strength and function in older adults.

Technical Abstract: Objectives This study examined the influence of lower extremity body composition and muscle strength on the severity of mobility-disability in community-dwelling older adults. Methods Fifty-seven older males and females (age 74.2 +/- 7 yrs; BMI 28.9 +/- 6 kg/m2) underwent an objective assessment of lower extremity functional performance, the Short Physical Performance Battery test (SPPB). Participants were subsequently classified as having moderate (SPPB score > 7: n = 38) or severe mobility impairments (SPPB score L 7: n = 19). Body composition was assessed using dual-energy X-ray absorptiometry and provided measures of bone mineral density (BMD), total leg lean mass (TLM) and total body fat. Maximal hip extensor muscle strength was estimated using the bilateral leg press exercise. Multiple logistic regression analysis was utilized to identify the significant independent variables that predicted the level of mobility-disability. Results TLM was a strong independent predictor of the level of functional impairment, after accounting for chronic medical conditions, BMD, body fat, body weight and habitual physical activity. In a separate predictive model, reduced muscle strength was also a significant predictor of severe functional impairment. The severity of mobility-disability was not influenced by gender (p = 0.71). A strong association was elicited between TLM and muscle strength (r = 0.78, p < 0.01). Conclusions These data suggest that lower extremity muscle mass is an important determinant of physical performance among functionally-limited elders. Such findings may have important implications for the design of suitable strategies to maintain independence in older adults with compromised physical functioning. Additional studies are warranted to assess the efficacy of lifestyle, exercise or therapeutic interventions for increasing lean body mass in this population.