Can Isometric Knee Extensor Torque from Hand-held Dynamometry Predict Physical Function in Overweight Older Adults?

Abstract

PURPOSE: Reduced muscular strength is associated with declines in functional capacity in older adults, and more field tests need to be developed in order to predict physical function in those who are at risk of sarcopenia- and obesity-related disability. The relationship between isometric knee extensor (KE) torque, handgrip strength (HGS) and tests of lower-extremity physical function was investigated in overweight and obese, community-dwelling older adults. METHODS: Overweight and obese (BMI = 33.4 ± 0.4 kg/m2), community-dwelling older (age = 68.9 ± 0.6 years) men and women (n = 108) underwent assessments of isometric KE torque, HGS, and completed two different measures of physical function. Maximal isometric KE torque was measured via hand-held dynamometry on the dominant leg and peak HGS values for the dominant hand were obtained using a hand-held dynamometer. Physical function was evaluated by the timed up-and-go test (TUG) and the short physical performance battery (SPPB). Individual subcomponents of the SPPB include a four-meter walk, quantitative assessments of balance, and a timed five chair stand test. The TUG measures the duration required to walk a short distance and provides an indication of functional mobility in older adults. A Spearman"s rank correlation coefficient analysis was conducted to investigate the association between performance on muscular function assessments and physical function tests. RESULTS: Maximal isometric KE torque was weakly but significantly correlated with peak HGS (+0.24, p=0.01). Peak HGS was significantly associated with total score on the SPPB (+0.20, p=0.04). Additionally, there was a significant inverse association between maximal HGS and time required to complete the TUG (-0.22, p=0.02). Interestingly, maximal isometric KE torque was not significantly associated with indices of lower-extremity physical function such as the TUG (-0.01, p=0.92) or the SPPB (+0.06, p=0.49). CONCLUSION: Although isometric KE torque from hand-held dynamometry is associated with HGS in overweight and obese, community-dwelling older adults, it may not adequately predict global measures of physical function. Peak HGS may have a better capacity to predict performance on measures of lower-extremity physical function in overweight and obese older adults.