Original articles  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2009 December;49(4):401-9

Copyright © 2010 EDIZIONI MINERVA MEDICA

lingua: Inglese

Effects of static stretching on the hamstrings-to-quadriceps ratio and electromyographic amplitude in men

Costa P. B., Ryan E. D., Herda T. J., Defreitas J. M., Beck T. W., Cramer J. T. ✉

Biophysics Laboratory, Department of Health and Exercise Science, University of Oklahoma, Norman, OK, USA

AIM: The purpose of this study was to examine the effects of posterior thigh and leg stretching on leg flexion peak torque (PT), leg extension PT, the hamstrings-to-quadriceps (H:Q) ratio, and electromyographic (EMG) amplitude of the hamstrings and quadriceps in recreationally-active men.
METHODS: Fifteen men (mean age±SD=22.0±4.4 years; body mass=82.7±16.1 kg; height=173.1±6.8 cm) performed three maximal voluntary concentric isokinetic leg extension and flexion muscle actions at three randomly ordered angular velocities (60, 180, and 300°.s-1) before and after hamstring and calf static stretching. The stretching protocol consisted of 1 unassisted and 3 assisted static stretching exercises designed to stretch the posterior muscles of the thigh and leg. Four repetitions of each stretch were held for 30 s with 20-s rest between repetitions.
RESULTS: These findings indicated no significant (P>0.05) stretching-induced changes in leg flexion PT, leg extension PT, or EMG amplitude at 60, 180, or 300°.s-1. However, the non-significant (P>0.05) 2-4% increases in leg extension PT combined with the non-significant (P>0.05) 1-2% decreases in leg flexion PT resulted in the significant (P≤0.05) 2-9% decreases in the H:Q ratio from pre- to post-stretching for all three velocities.
CONCLUSIONS: These findings suggested that static stretching of the hamstrings and calf muscles may decrease the H:Q ratio. These results may be useful for athletic trainers, physical therapists, and other allied health professionals who may use the H:Q ratio as a clinical assessment.