Changes in Vertical and Joint Stiffness in Runners With Advancing Age.

Powell, DW and Williams, DSB. Changes in vertical and joint stiffness in runners with advancing age. J Strength Cond Res 32(12): 3425-3431, 2018-Age-related changes in the neuromuscular system underlie reduced performance and injury but may be mitigated through regular physical activity. It was hypothesized that older (OLD) compared with young (YOUNG) adults would exhibit greater vertical and joint stiffness when running at 3.35 m·s. Nine YOUNG and 10 OLD runners performed over ground running trials while three-dimensional biomechanics were recorded. Ankle and knee joint angles, moments and stiffness values were compared between YOUNG & OLD. YOUNG had smaller vertical stiffness (p = 0.01; YOUNG: 32.8 ± 3.6; OLD: 38.1 ± 5.7) and greater joint stiffness than OLD at the ankle (p = 0.04; YOUNG: 0.134 ± 0.021; OLD: 0.118 ± 0.017) and knee (p = 0.01; YOUNG: 0.119 ± 0.016; OLD: 0.098 ± 0.014). YOUNG exhibited greater peak knee flexion angles (p = 0.04; YOUNG: 43.4 ± 6.5°; OLD: 39.1 ± 2.6°), and peak ankle plantarflexion (p = 0.02; YOUNG: -2.8 ± 0.4 Nm·kg; OLD: -2.5 ± 0.1 Nm·kg) and knee extension moments (p < 0.01; 2.6 ± 0.3 Nm·kg; OLD: 2.1 ± 0.2 Nm·kg) than OLD whereas no differences were observed in peak ankle dorsiflexion angles (p = 0.44; YOUNG: 23.6 ± 4.2°; OLD: 23.4 ± 2.1°). The findings of this study suggest that OLD compared with YOUNG adults adopt altered lower extremity biomechanics. These altered running biomechanics by seek to minimize the metabolic cost of running or may be a function of reduced lower extremity strength and power.