HEAVY RESISTANCE TRAINING CHANGES THE STRETCH-SHORTENING CYCLE OF THE MOVEMENTS TRAINED BUT POSSIBLY AT DIFFERENT VELOCITIES
Jakobsen, M. D., Sundstrup, E., Krustrup, P., & Aagaard, P. (2009). Does progressive strength training improve stretch-shortening cycle muscle performance? ACSM 56th Annual Meeting, Seattle, Washington, Presentation Number 726.
This study evaluated the effect of strength training on the stretch-shortening cycle of muscle performance during countermovement jumping in untrained men (N = 8). Ss performed progressive heavy-resistance strength training twice a week for 12 weeks. Training loads ranged from 6-10 RM with the first four weeks ranging 12-16 RM. Training exercises were squat, hack squat, incline leg pres, isolated knee extension, hamstring curls and calf raises. All training exercises were performed as slow stretch-shortening cycles. Countermovement jumps were performed with hands on the hips on a force platform.
Maximal countermovement jump height increased 15% with training. Peak and mean power exerted during the concentric phase of the countermovement jump increased by 12 % and 19 %, respectively. Downward peak velocity increased 26% and the deceleration phase was shortened by 17%.
Implication. Progressive heavy strength training enhanced the stretch-shortening cycle performance factors of increased downward velocity, a more rapid eccentric deceleration phase, elevated power production during the propulsive takeoff phase, and increased maximal jump height during countermovement jumping. [The activity trained was altered, however, performance velocity factors not trained appear to have been altered.]
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