Lower-Extremity Torque Capacity and Physical Function in Mobility-Limited Older Adults

• Published in: The Journal of nutrition, health & aging Vol. 23; no. 8; pp. 703 - 709
• Main Authors: Grosicki, Gregory J., Englund, D. A., Price, L., Iwai, M., Kashiwa, M., Reid, K. F., Fielding, R. A.
• Format: Journal Article
• Language: English
• Published: Paris Springer Paris 01.08.2019; Springer Nature B.V
• Subjects: Aged; Aged, 80 and over; Aging; Female; Geriatrics/Gerontology; Humans; Lower Extremity - physiology; Male; Medicine; Medicine & Public Health; Mobility; Muscle Strength - physiology; Muscle, Skeletal - physiology; Musculoskeletal system; Neurosciences; Nutrition; Older people; Primary Care Medicine; Product design; Quality of Life Research; Sarcopenia; Strength training; Torque; older adults; physical function; torque capacity; Skeletal muscle; sarcopenia
• ISSN: 1279-7707; 1760-4788
• DOI: 10.1007/s12603-019-1232-8

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.