Ten‐year longitudinal changes in muscle power, force, and velocity in young, middle‐aged, and older adults

Abstract

Abstract Background Maximum muscle power (P max ) is a biomarker of physical performance in all ages. No longitudinal studies have assessed the effects of aging on P max obtained from the torque‐velocity (T‐V) relationship, which should be considered the ‘gold standard’. This study evaluated the longitudinal changes in the T‐V relationship and P max of the knee‐extensor muscles in young, middle‐aged, and older adults after 10 years of follow‐up. Methods Four hundred eighty‐nine subjects (311 men and 178 women; aged 19–68 years) were tested at baseline and after a 10‐year follow‐up. Anthropometric data, daily protein intake, physical activity level (PAL), and knee‐extension muscle function (isometric, isokinetic, and isotonic) were evaluated. A novel hybrid equation combining a linear and a hyperbolic (Hill‐type) region was used to obtain the T‐V relationship and P max of the participants, who were grouped by sex and age (young: 20–40 years; middle‐aged: 40–60 years; and old: ≥60 years). Linear mixed‐effect models were used to assess effects of time, sex, and age on T‐V parameters, P max , and body mass index (BMI). Additional analyses were performed to adjust for changes in daily protein intake and PAL. Results P max decreased in young men (−0.6% per year; P < 0.001), middle‐aged men and women (−1.1% to −1.4% per year; P < 0.001), and older men and women (−2.2% to −2.4% per year; P ≤ 0.053). These changes were mainly related to decrements in torque at P max at early age and to decrements in both torque and velocity at P max at older age. BMI increased among young and middle‐aged adults (0.2% to 0.5% per year; P < 0.001), which led to greater declines in relative P max in those groups. S /T 0 , that is, the linear slope of the T‐V relationship relative to maximal torque, exhibited a significant decline over time (−0.10%T 0 ·rad·s −1 per year; P < 0.001), which was significant among middle‐aged men and old men and women (all P < 0.05). Annual changes in PAL index were significantly associated to annual changes in P max ( P = 0.017), so the overall decline in P max was slightly attenuated in the adjusted model (−5.26 vs. −5.05 W per year; both P < 0.001). Conclusions P max decreased in young, middle‐aged, and older adults after a 10‐year follow‐up. The early declines in P max seemed to coincide with declines in force, whereas the progressive decline at later age was associated with declines in both force and velocity. A progressively blunted ability to produce force, especially at moderate to high movement velocities, should be considered a specific hallmark of aging.

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