Repeated sit-to-stand exercise enhances muscle strength and reduces lower body muscular demands in physically frail elders
School of Medical and Health Sciences / Exercise Medicine Research Institute
To examine the effect of a conditioning program consisting of repeated sit-to-stand exercise on knee extensor strength and muscular activities during body mass-based squat movement in physically frail elders.
Fourteen men and women aged 75 to 88 years who used the long-term care insurance system participated in the 12-week training program (48 reps/session, 3 sessions/week). Isometric knee extension torque (KET) during a maximum voluntary contraction (MVC) and electromyogram (EMG) activities of the rectus femoris and vastus lateralis muscles during the MVC and a body mass-based squat task were determined at baseline, and following 4 and 12 weeks training. KET was expressed relative to body mass (KET/BM) and EMG activities during the squat task were normalized to that during a MVC and averaged (QF %EMGmax).
KET/BM increased from 1.07 ± 0.28 Nm/kg at baseline to 1.26 ± 0.26 Nm/kg at week 4 and 1.31 ± 0.28 Nm/kg at week 12 (P < 0.001), and QF %EMGmax decreased from 67.2 ± 17.2% to 49.3% at week 4 (P < 0.001) and 43.5 ± 7.7% at week 12 (P = 0.016). At each of the three measurement time points KET/BM was inversely correlated with QF %EMGmax (r = −0.78 to −0.86, P ≤ 0.001).
For physically frail elders, a short-term conditioning program consisting of repeated sit-to-stand exercise is effective in increasing knee extensor strength and reducing the muscular effort required for lowering and raising the body.
Exercise, nutrition, lifestyle and other interventions for optimal health across the lifespan