EMG Onset after a 10-Week Stretching Intervention: A Comparison between Older and Younger Adults

Haab T, Massing M, Wydra G. EMG Onset after a 10-Week Stretching Intervention: A Comparison between Older and Younger Adults. JEPonline 2017;20(4):121-131. The purpose of this study was to investigate the effect of a standardized 10-wk stretch training program on flexibility and EMG onset in older and younger adults. Subjects undertook static stretch training of the ischiocrural muscles. Data were collected using a straight leg raise test. Maximum range of motion ([RoM.sub.max.]) and both absolute EMG onset ([EMG.sub.onset]) and relative EMG onset ([EMG.sub.onset-%]) were recorded. Following training, both age groups showed an increased [RoM.sub.max.] ([degrees]) ([RoM.sub.max.-old]: 86.70 [+ or -] 14.90 vs. 94.72 [+ or -] 15.65, [RoM.sub.max.-young]: 93.00 [+ or -] 15.44 vs. 101.40 [+ or -] 13.01). The absolute [EMG.sub.onset] ([degrees]) remained virtually unchanged over the period of time ([EMG.sub.onset-old]: 69.19 [+ or -] 5.21 vs. 70.67 [+ or -] 4.83, [EMG.sub.onset-young]: 68.66 [+ or -] 17.86 vs. 68.84 [+ or -] 18.13). The relative [EMG.sub.onset-%] (%) decreased in both age groups ([EMG.sub.onset-%-old]: 77.30 [+ or -] 11.64 vs. 71.79 [+ or -] 6.07, [EMG.sub.onset-%-young]: 74.33 [+ or -] 16.57 vs. 68.24 [+ or -] 17.03). Overall, the results showed no difference based on age in the change in flexibility or EMG onset after a long-term stretch training. Both the younger and older age groups benefited to the same extent from the 10-wk stretching intervention. Although flexibility did increase, the absolute EMG onset remained relatively similar over the intervention period. Therefore, it can be assume that EMG onset has no effect on flexibility. Key Words: Age, EMG Onset, Skeletal Muscle, Stretching