Associations between novel jump test measures, grip strength, and physical performance: the Osteoporotic Fractures in Men (MrOS) Study

Background/aims: Weight-bearing jump tests measure lower extremity muscle power, velocity, and force, and may be more strongly related to physical performance than grip strength. However, these relationships are not well described in older adults. Methods: Participants were 1242 older men (mean age 84 ± 4 years) in the Osteoporotic Fractures in Men (MrOS) Study. Jump peak power (Watts/kg body weight), force (Newton/kg body weight) at peak power, and velocity (m/s) at peak power were measured by jump tests on a force plate. Grip strength (kg/kg body weight) was assessed by hand-held dynamometry. Physical performance included 400 m walk time (s), 6 m usual gait speed (m/s), and 5-repeated chair stands speed (#/s). Results: In adjusted Pearson correlations, power/kg and velocity moderately correlated with all performance measures (range r = 0.41–0.51; all p < 0.001), while correlations for force/kg and grip strength/kg were weaker (range r = 0.20–0.33; all p < 0.001). Grip strength/kg moderately correlated with power/kg (r = 0.44; p < 0.001) but not velocity or force/kg. In adjusted linear regression with standardized βs, 1 SD lower power/kg was associated with worse: 400 m walk time (β = 0.47), gait speed (β = 0.42), and chair stands speed (β = 0.43) (all p < 0.05). Associations with velocity were similar (400 m walk time: β = 0.42; gait speed: β = 0.38; chair stands speed: β = 0.37; all p < 0.05). Force/kg and grip strength/kg were more weakly associated with performance (range β = 0.18–0.28; all p < 0.05). Conclusions/discussion: Jump power and velocity had stronger associations with physical performance than jump force or grip strength. This suggests lower extremity power and velocity may be more strongly related to physical performance than lower extremity force or upper extremity strength in older men.