Date of Award
Master of Arts
Health, Physical Education & Recreation
Dr. Mark D. Ricard
Masters Thesis-Open Access
The purpose of this study was to test how changing the bicycle frame geometry; from a shallow frame geometry [seat tube angle (STA) of 72°] to a steep frame geometry (STA of 82°) affected the electromyographic (EMG) signal of the hamstrings [biceps femoris (BF) and semitendinosus (ST) muscles] and the quadriceps [vastus medialis (VM) and vastus lateralis (VL)] and power (max, mean, min, and, % drop) during a Wingate anaerobic test (WAT). To measure the muscle recruitment and power, 12 experienced triathletes were prepped with surface electrodes to measure EMG amplitude and an electrogoniometer to measure knee joint angle while performing a WAT. EMG normalization was performed using maximal voluntary contractions of knee flexion and extension at knee joint angle of 45°. Muscle recruitment was not changed across the STA for the BF, VM, and VL.
The ST did show a significant interaction in both STA from the start of the test with EMG amplitudes of 54.61 ± 20.88% MVC and 53.35 ± 27.91% MVC to the end of the test, 65.12 ± 30.86% MVC and 45.44 ± 15.99% MVC (p = 0.049). During a WAT, there are no differences in power production or muscle recruitment patterns for the BF, VM, and VL, however there is a significant difference in muscle recruitment for the ST with less muscle activation at a STA of 82° versus 72°. There were no significant differences in power across the two STA. The reason for the use of a steeper STA in triathlon is not therefore for the power purpose, it is for the comfort and decrease in activation of specific muscles.
Hills-Meyer, Patrick, "The Effects of Differing Bicycle Frame Geometry on Muscle Recruitment Strategies and Power During A 30-Second Wingate Anaerobic Test" (2004). Masters Theses. 5322.