DO EXERCISE INTERVENTIONS RESTORE OLD ADULTSʼ GAIT TO A YOUNG GAIT?
Tibor Hortobágyi – University Medical Center, University of Groningen, Groningen, The Netherlands Relevance.
Walking ability is a cornerstone of quality of life and a disproportionately slow gait in midlife predicts numerous clinical conditions later in life (Abellan van Kan et al., 2009; Studenski et al., 2011). It is thus important to reduce gait speed loss in old adults. Biomechanical analyses of old adultsʼ gait reveal an overreliance on hip muscle mechanical output, inconsistent changes in knee mechanics, and reductions in mechanical output at the ankle joint. Such a distal-to-proximal shift in mechanics, i.e., biomechanical plasticity of gait in old age, occurs independent of gender and speed (DeVita & Hortobágyi, 2000). It is however unknown if the exercise interventions-induced 0.1 m/s or 8.4 % increases in gait speed (Hortobágyi et al., 2015) are accompanied by a reconfiguration of old gait to young gait (Beijersbergen et al., 2013). The aim of this paper is to provide an overview on the effects of lower extremity power training on healthy old adultsʼ gait biomechanics. Methods. Healthy old adults completed a no-intervention control period (69.1 ± 4.4 y, n = 14) or a 10- week-long power training of lower extremity muscles, consisting of 30 sessions (72.9 ± 5.4 y, n = 15). Participants performed comprehensive lower extremity leg muscle power training at 40–60 % of the 3-repetition maximum and were instructed to move the weights as rapidly and explosively as possible during the concentric phase. We measured isokinetic knee extensor and plantarflexor power and hip, knee and ankle kinetics at habitual and fast walking speeds, using inverse dynamics analyses (Beijersbergen et al., 2016). Results and discussion. Isokinetic knee extensor (25 %) and plantarflexor power (43 %), and fast gait velocity (5.9 %) increased after power training of leg muscles (all p < .05). Gait mechanics underlying the increases in fast gait velocity included increases in hip angular impulse (29 %) and hip extensor work (37 %) but no changes in knee and ankle positive (propulsive) muscle work. Thus, a specific form of exercise intervention did not convert healthy old adultsʼ gait mechanics to a gait resembling young gait. Instead, it further increased the age-induced reliance on hip function and did not correct the age-associated reductions in ankle mechanical output (Beijersbergen et al., 2017). Ongoing work, however, does suggest that it may still be possible to improve the age-induced reductions in ankle function during gait because power training of leg muscles using leg press improved ankle muscle power measured during gait by inverse dynamics and these increases correlated with increases in habitual and fast gait velocity, respectively, R 2 = 0.58 and R 2 = 0.67 (both p < .05, n = 15, age 74.3) (Uematsu et al., 2017). In total, lower extremity power training increases healthy old adultsʼ walking speed, but the mechanisms are still unclear and whether such increases are due to a reconfiguration of gait mechanics to a young gait.
