Allometric analysis of physical performance measures in older adults

BACKGROUND AND PURPOSE: Body mass is a confounding variable in human performance, and adjusting physical performance measures for body mass differences would allow meaningful individual and group comparisons. The purpose of this study was to allometrically determine the relationship between body mass and handgrip and ankle dorsiflexor performance on the Timed "Up & Go" Test (TUGT). SUBJECTS: One hundred thirty-one subjects (33 male and 98 female) participated. METHODS: All physical performance measures were adjusted for the influence of body mass, sex, and age using an allometric scaling procedure. RESULTS: For handgrip force, the body mass exponent from allometric analysis was 0.63. For the TUGT, the body mass exponent was 0.073. For ankle dorsiflexor force and torque, the body mass exponents were 0.82 and 0.91, respectively. DISCUSSION AND CONCLUSION: The body mass exponents for handgrip force and the TUGT agree with previous clinical data and theoretical expectations. Studies investigating normalized handgrip force in older adults should consider an allometric scaling approach.