| Sumario: | Purpose During hopping, jumping and running, the musculoskeletal structure of the legs is often modelled with a spring-mass model, which consists of a body mass and a linear leg spring supporting the body mass1. In the model, the stiffness of the leg spring (leg stiffness; Kleg) is thought to be an important factor in musculoskeletal performance2. However, despite the fact that many athlete's activities are often measured, little is known about the regulation of Kleg in the elderly. Therefore, the purpose of the present study was to compare the Kleg between the elderly and young subjects in a range of hopping frequency. Method Fourteen elderly and eleven young subjects performed in-place hopping, matching metronome beats at 2.2, 2.6 and 3.0Hz. Based on the spring-mass model, Kleg was calculated as the ratio of maximum ground reaction force to maximum center of mass displacement at the midstance (Figure 1). Results & Discussion In both groups, the Kleg increased with an increase in hopping frequency, but was not significantly different between groups (Figure 2). Statistical analysis revealed the existence of a significant main effect of hopping frequency on Kleg. However, main effect of groups and interaction on Kleg were not observed. The results of the present study indicate that leg stiffness during hopping is invariant with aging. Since too high or too low Kleg is associated with musculoskeletal injury2, footwear and/or surface materials, impact on Kleg2 should be considered for athletic environment in both master and young athletes.
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