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International Journal of Biotechnology and Bioengineering




With widespread use of pre-exercise stretching methods across sport and exercise, recent studies have questioned the effectiveness of such methods (Kay & Blazevich 2012; Cramer et al., 2005; Curry, Chengkalath, Crouch, Romance, & Manns, 2009). The purpose of this study was to examine how the relationship between pennation angle, proprioception, and muscle power are influenced by a static stretching protocol. Participants (n = 17) from a southeastern university in the United States consented to participate and were divided into an experimental group (n = 12) and control group (n = 5). The experimental group engaged in static stretched by placing the right foot on an incline board and maximally dorsiflexing the ankle joint while keeping the bottom of their foot flush with the board’s surface and the knee fully extended. The control group remained seated for the same amount of time and did not engage in stretching. Both groups were measured for vertical jump using the Vertec force plate, electrical activity of the gastrocnemius via the Terason ultrasound machine, and proprioception of the ankle joint via the Biodex 2 dynamometer pre- and post- stretching and control protocols. Results indicated that static stretching resulted in a decrease in muscle power without change of proprioception or electrical-mechanical delay while accompanied by an increase in pennation angle. The increase in pennation angle may the reason why static stretch resulted in a reduction in muscle power. The results are discussed in regard to previous research and future practical application.


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