Effects of flywheel training with eccentric-overload on standing balance, mobility, physical function, muscle thickness and muscle quality in older adults

The present study investigated the effects of a 6-week eccentric overload flywheel training programme on vastus lateralis (VL) and gastrocnemius medialis (GM) muscle thickness and muscle quality (echo intensity), mobility (Timed-Up-and-Go [TUG]), physical function (sit-to-stand) and balance (postural sway) performance. Nineteen subjects were assigned to either a flywheel training group (n = 11, age = 66.4 ± 5.2 y) or a control group (n = 8, age = 65.9 ± 3.8 y). The flywheel group underwent twice-weekly squat and calf raise exercises for 6 weeks with outcome measures assessed before and after training or a time-matched control period. Throughout the training, participants were instructed to contract as fast as possible with maximal effort during the concentric phase and to maximally resist the pull during the eccentric phase. The alpha value was a priori set at p < 0.05. Statistically significant (p < 0.05) mean [SD] increases in right and left VL (7.6 – 9.6 ± 7.7 – 9.8%) and GM (8.6 – 8.7 ± 6.4 – 11.5%) muscle thickness and a reduction in VL (10.2 – 11.3 ± 5.9 – 7.9 %) and GM (11.7 – 11.9 ±5.6 – 9.6%) echo intensity were accompanied by faster TUG time (13.7 ± 7.0%), improved sit-to-stand performance (17.8 –23.5 ± 7.6 – 13.4%) and reduced postural sway (29.7 – 42.3 ± 13.2 – 24.2%) following 6 weeks of flywheel training. There were no differences in any outcome measures between the treatment and control group at baseline (p > 0.05). Overall, we observed substantial gains in muscle thickness and muscle quality, in addition to enhanced physical function, balance and mobility performance among older adults following flywheel training, which may have important implications for preserving the functional capacity of older adults.