STRETCHING REDUCES FUNCTIONAL STRENGTH IN THE HAMSTRINGS AND QUADRICEPS IN WOMEN

Costa, P. B., Ryan, E. D., Herda, T. J., Walter, A. A., Valdez, A. M., & Cramer, J. T. (2011). Effects of dynamic stretching on peak torque and the hamstrings-to-quadriceps conventional and functional ratios. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 1643.

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This study examined the acute effects of dynamic stretching on leg extensor and flexor concentric peak torque, leg flexor eccentric peak torque, and the conventional end functional hamstrings:quadriceps ratios during isokinetic muscle actions. Women (N = 21) performed three maximal voluntary unilateral isokinetic leg extension, flexion, and eccentric hamstring muscle actions at the angular velocities of 60 and 180 per second before and after a bout of dynamic hamstring and quadriceps stretching and a control condition. Four sets of four dynamic stretching exercises were performed with each set lasting 30 seconds with 15 seconds rest periods between sets. Two exercises were for the anterior muscles of the thigh and two for the posterior muscles of the thigh. The control condition consisted of quiet sitting between pre- and post-tests.

Leg flexion peak torque decreased under both control and stretching conditions while eccentric hamstrings peak torque decreased only following the stretching intervention. The results indicated no changes in leg extension peak torque. Conventional hamstrings:quadriceps ratios decreased under both control and stretching conditions, whereas functional hamstrings:quadriceps ratios decreased only after stretching.

Implication. Dynamic stretching caused hamstring concentric peak torque and conventional hamstrings:quadriceps ratio decreases to a greater magnitude than a control condition. In addition, dynamic stretching decreased eccentric hamstring peak torque and the functional hamstrings:quadriceps ratio.

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