Location: Jean Mayer Human Nutrition Research Center On AgingTitle: Lower-extremity torque capacity and physical function in mobility-limited older adults
|GROSICKI, GREGORY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|ENGLUND, DAVIS - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|PRICE, LORI - Tufts Medical Center|
|IWAI, MEGUMI - Astellas Pharma Inc|
|KASHIWA, MAKOTO - Astellas Pharma Inc|
|REID, KIERAN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
|FIELDING, ROGER - Jean Mayer Human Nutrition Research Center On Aging At Tufts University|
Submitted to: Journal of Nutrition Health and Aging
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2019
Publication Date: 8/3/2019
Citation: Grosicki, G.J., Englund, D.A., Price, L.L., Iwai, M., Kashiwa, M., Reid, K.F., Fielding, R.A. 2019. Lower-extremity torque capacity and physical function in mobility-limited older adults. Journal of Nutrition Health and Aging. 23:703-709. https://doi.org/10.1007/s12603-019-1232-8.
Interpretive Summary: For decades scientists have sought to understand how age-related declines in skeletal muscle size, strength and endurance detract from physical function. This study used a novel leg muscle testing protocol to capture multiple muscle contractile characteristics, and then explored their association with a few highly meaningful measures of physical function (e.g., time to climb a flight of stairs or stand up out of a chair). Strong relationships between leg muscle measures obtained using this novel testing protocol and physical function highlight the utility of this time-efficient assessment technique to identify clinically relevant skeletal muscle deficits. Future studies are encouraged to consider using this innovative muscle testing protocol when evaluating leg muscle contractile performance in older adults.
Technical Abstract: OBJECTIVES: Skeletal muscle weakness and an increase in fatigability independently contribute to age-related functional decline. The objective of this study was to examine the combined contribution of these deficiencies (i.e., torque capacity) to physical function, and then to assess the functional implications of progressive resistance training (PRT) mediated torque capacity improvements in mobility-limited older adults. DESIGN: Randomized controlled trial. SETTING: Exercise laboratory on the Health Sciences campus of an urban university. PARTICIPANTS: Seventy mobility-limited (Short Physical Performance Battery (SPPB) = 9) older adults (~79 yrs). INTERVENTION: Progressive resistance training or home-based flexibility 3 days/week for 12 weeks. MEASUREMENTS: Torque capacity was defined as the sum of peak torques from an isokinetic knee extension fatigue test. Relationships between torque capacity and performance-based and patient-reported functional measures before and after PRT were examined using partial correlations adjusted for age, sex, and body mass index. RESULTS: Torque capacity explained (P<0.05) 10 and 28% of the variance in six-minute walk distance and stair climb time, respectively. PRT-mediated torque capacity improvements were paralleled by increases (P<0.05) in self-reported activity participation (+20%) and advanced lower extremity function (+7%), and associated (P<0.05) with a reduction in activity limitations (r=0.44) and an improved SPPB score (r=0.32). CONCLUSION: Skeletal muscle torque capacity, a composite of strength and fatigue, may be a proximal determinant of physical function in mobility-limited older individuals. To more closely replicate the musculoskeletal demands of real-life tasks, future studies are encouraged to consider the combined interaction of distinct skeletal muscle faculties to overall functional ability in older adults.