Chad R. Straight

Sex-specific relationships of physical activity, body composition, and muscle quality with lower-extremity physical function in older men and women.

ObjectiveThis study aims to determine the sex-specific relationships of physical activity, body composition, and muscle quality with lower-extremity physical function in older men and women. MethodsSeventy-nine community-dwelling men (n = 39; mean [SD] age, 76.1 [6.2] y; mean [SD] body mass index, 27.3 [3.8] kg/m2) and women (n = 40; mean [SD] age, 75.8 [5.5] y; mean [SD] body mass index, 27.0 [3.8] kg/m2) were assessed for physical activity via questionnaire, body composition via dual-energy x-ray absorptiometry scanning, leg extension power using the Nottingham power rig, and muscle quality (W/kg; the ratio of leg extension power [W] to lower-body mineral-free lean mass [kg]). A composite measure of physical function was obtained by summing Z scores from the 6-minute walk, 8-ft up-and-go test, and 30-second chair-stand test. ResultsAs expected, men had significantly greater levels of physical activity, lower adiposity, greater lean mass, higher leg extension power, and greater muscle quality compared with women (all P < 0.05). In linear regression analyses, muscle quality and physical activity were the strongest predictors of lower-extremity physical function in men and independently explained 42% and 29% of the variance, respectively. In women, muscle quality (16%) and percent body fat (12%) were independent predictors after adjustment for covariates. ConclusionsMuscle quality is the strongest predictor of lower-extremity physical function in men and women, but sex impacts the importance of physical activity and adiposity. These findings suggest that older men and women may benefit from different intervention strategies for preventing physical disability and also highlight the importance of weight management for older women to preserve physical function.

Resistance training in older adults: are community-based interventions effective for improving health outcomes?

Sarcopenia is associated with substantial health and economic consequences and is emerging as a major public health problem in the older population. The effects of sarcopenia may increase the risk for adverse health outcomes in older adults, and strategies need to be developed to maintain healthy aging. Although several intervention strategies have been proposed, resistance training (RT) has been suggested as the most effective stimulus for optimizing improvements in physical function and body composition with age. Although RT has been established as a safe and efficacious intervention for the prevention and treatment of sarcopenia, very few older adults regularly participate in RT programs. Community-based RT programs may be a feasible strategy because of their accessibility, cost-effectiveness, and lower-intensity training stimuli. However, the effects of these interventions on health outcomes in older adults have not been adequately reviewed. This report will describe the health effects associated with sarcopenia and summarize the major findings from community-based RT interventions on different health outcomes in older adults. Finally, it is suggested that all older adults who demonstrate the ability to safely participate in RT comply with the guidelines recommended by the American College of Sports Medicine.

Asymmetry in leg extension power impacts physical function in community-dwelling older women.

Objective:The aim of this study was to examine the association between asymmetry in leg extension power (LP) and lower-extremity physical function (LEF) in community-dwelling older women. Methods:Older women (n = 94, 74.0 ± 5.5 y) were assessed for unilateral LP (watts) using the Nottingham power rig, and absolute and relative (%ASYM) differences in LP between the dominant and nondominant legs were calculated. LEF was assessed via the 6-minute walk, 8-foot up-and-go and 30-second chair stand, and a composite measure of LEF was calculated by summing z scores of each test. In addition, body composition was measured via dual-energy x-ray absorptiometry and moderate-intensity physical activity was assessed via questionnaire. Results:The absolute difference in LP between the dominant and nondominant legs was 10.2 ± 9.0 watts, which translated to a %ASYM of 11.3% ± 10.5% (P < 0.01). %ASYM had bivariate associations with all individual measures of LEF (r range = −0.22 to −0.34, all P < 0.05). Using multivariate linear regression, %ASYM was an independent predictor of a composite LEF z score (standardized &bgr; = −0.18, P < 0.05) after adjustment for age, comorbidities, physical activity, relative adiposity, and total leg power. Analysis of covariance indicated that women with low asymmetry had a significantly better LEF z score than those with high asymmetry (0.60 vs −0.13, P = 0.04). Conclusions:These findings indicate that a greater magnitude of asymmetry in LP is associated with poorer LEF in older women. Research is needed to determine whether interventions that correct asymmetries in lower-body muscle power confer functional benefits in older women.