This study examined the acute effects of passive stretching on electromechanical delay (EMD), peak twitch force (PTF), rate of force development (RFD), and peak-to-peak M-wave (PPM) for the soleus muscle during evoked isometric plantar flexion muscle actions. Fourteen men (mean age ± SD = 21.2 ± 2.4 years; body mass = 80.0 ± 14.9 kg; height = 176.9 ± 7.2 cm) and 20 women (20.9 ± 2.5 years; 61.3 ± 8.9 kg; 165.3 ± 7.5 cm) volunteered for the study. Five single-square, supramaximal transcutaneous electrical stimuli (each separated by 5 s) were delivered to the tibial nerve before and after passive stretching. A time × gender interaction was observed for EMD, and the post hoc dependent-samples t tests indicated that EMD increased 4% for the women (p = .023), but not for the men (p = .191). There were no other stretching-related changes for PTF, RFD, or p-p M-wave for either the men or women (p > .05). These findings tentatively suggested that mechanical factors related to the stiffness of the muscle-tendon unit may contribute to the explanation for why stretching caused an acute increase in the EMD during evoked twitches in the women, but not in the men.
Pablo B. Costa (Corresponding Author) is with the Human Performance Laboratory, Department of Kinesiology, California State University, San Bernardino, CA. Eric D. Ryan is with the Neuromuscular Research Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC. Trent J. Herda is with the Biomechanics Laboratory, Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence, KS. Ashley A. Walter is with the Department of Ophthalmology, University of Kansas School of Medicine, Prairie Village, KS. Katherine M. Hoge is with the Biophysics Laboratory, Department of Health and Exercise Science, University of Oklahoma, Norman, OK. Joel T. Cramer is with the Department of Nutrition and Health Sciences, University of Nebraska–Lincoln, Lincoln, NE.