Introduction: Both grip and knee extension strength are often used to characterize overall limb muscle strength. We sought to determine if the measures actually reflect a common construct.
Methods: The isometric grip and knee extension strength of 164 healthy men and women (range, 18-85 years) were measured bilaterally using standard procedures. Pearson correlations (r), Cronbach alpha, principal components analysis, and multiple regression/correlation were used to investigate the dimensionality of the measures.
Results: Left and right grip forces and knee extension torques were highly correlated, internally consistent, and loaded on a single component. Gender and age explained the variance in both measures, but height added to the explanation of grip strength, whereas weight added to the explanation of knee extension strength.
Conclusions: Among healthy adults, grip and knee extension strength reflect a common underlying construct. The measures, however, are affected differently by height and weight.
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