Effects of Stable and Unstable Resistance Training in an Altered-G Environment on Muscle Power

Abstract The study evaluated the effect of 4 weeks of combined resistance-balance training and resistance training alone in a 90° tilted environment on muscle power. Two groups of healthy young subjects performed leg extensions while in a supine position, either on a firm surface along a linear track or on an unstable surface requiring mediolateral balancing movements. Power and force during squats were measured at isokinetic velocities of 10 and 35 deg/s. Results showed significantly greater gains in peak force (44.1%; F 1,21 =8.876, p =0.026), mean force (58.6%; F 1,21 =16.136, p =0.013), peak power (58.7%; F 1,21 =18.754, p =0.009), and mean power (59.2%; F 1,21 =23.114, p =0.007) at the velocity of 35 deg/s after stable than unstable resistance training. However, there were no significant between-groups differences in pre-post training gains in peak force (10.4%; F 1,21 =1.965, p =0.74), mean force (10.3%; F 1,21 =1.889, p =0.80), peak power (12.9%; F 1,21 =2.980, p =0.49), and mean power (19.1%; F 1,21 =3.454, p =0.36) during squats at the velocity of 10 deg/s. Resistance exercises under stable conditions performed in a 90° tilted environment are more effective in the improvement of high velocity muscle power than their use in combination with balance exercises. Such training may be applicable in pre- and in-flight exercise regimens for astronauts and in functional rehabilitation of bed-ridden patients.