Knee extension torque, range of hip joint flexion, and electromyography of the knee extensors before and after dynamic stretching

Abstract

[Purpose] To clarify the effect of dynamic stretching (DS), we compared the range of hip flexion, the peak torque of knee extension, and the characteristics of surface electromyography of the knee extensors between before and after DS. [Subjects] Twenty-three healthy men participated in this study. [Methods] The range of motion of hip flexion and the peak torque of knee extension were measured before, immediately after, and 10 minutes after DS. Surface electromyography was conducted at the same time as the peak torque measurement. [Results] The range of motion, the peak torque and the median power frequency (MdPF) significantly increased immediately after DS, and at 10 minutes after DS, compared with before DS. [Conclusion] The range of motion was increased by DS. With regard to the integrated electromyography, MdPF and scalogram showed no differences in the recruitment of motor units by DS, but the recruitment pattern of motor units qualitatively changed, being concentrated in a short time frame.