Purpose: This study recruited bicycle enthusiasts and investigated lower extremity muscle activation at various seat-tube angles. Methods: Twenty healthy participants (10 males and 10 females) with right dominant leg were recruited for this study. We recorded the rectus femoris, hamstring, tibialis anterior, and gastrocnemius medialis in five different seat-tube angles conditions at 59, 69, 79, 89, 99 degrees. One-way analysis of variance with repeated measures was used to analyze all the data. The level of significance was set at = .05. Results: A large bicycle seat-tube angle reduced the muscle activation of the rectus femoris, hamstring and gastrocnemius during the downstroke phase. However, when the seat-tube angle was increased to 99°, the muscle activation of the rectus femoris and hamstring increased. In addition, the activation of tibialis anterior muscle decreased as the seat-tube angle increased. Conclusions: Lower extremity function can be changed by adjusting the seat-tube angle. At seat-tube angles of less than 90°, a larger seat-tube angle can enhancing pedaling efficiency. For lower extremity, a seat-tube angle greater than 90° can be used for rehabilitation and training.
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