The effects of hip angle manipulation on submaximal oxygen consumption in collegiate cyclists
Klippel, Nathan John.
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The purpose of this study was to determine the effects of hip angle (HA) manipulation on submaximal oxygen consumption (VO2SUB) in collegiate cyclists. Sixteen collegiate cyclists (Mean±SD; 23.3±3.5 years; 73.3±5.9 kg body mass; 4.54±0.34 L/min VO2MAX) were tested in five positions, each resulting in a different HA, on a cycling ergometer. The positions tested were centered around the mean HA corresponding to each cyclist's preferred position (P0), defined as the combination of trunk angle (TA) and seat tube angle (STA) in which each cyclist self-reported spending most of their time training on a bicycle. The five positions tested were the cyclist's P0 and positions resulting in mean HA's of +10°, +5°, -5°, and -10° relative to their P₀. All cyclists were tested in each of the positions at a power output corresponding to 85% of ventilatory threshold. Sagittal-view kinematics for mean HA, TA, knee angle (KA) and ankle angle (AA) were recorded to confirm that HA was the only positional measurement being manipulated. Kinematic measures confirmed that mean TA, KA, and AA were not significantly different (P>0.05).Furthermore, it was confirmed that all HA's were significantly different (P>0.05) except between the positions +5° and +10° greater than that that corresponding to P₀. No significant differences were found when comparing VO2SUB (P>0.05), heart rate (P>0.05), or minute ventilation (Ve; P>0.05) across the five positions. Nonsignificant quadratic trends were found for all three physiological measures across the five positions. It appears that VO2SUB, HR, and Ve are all minimized at positions equivalent to P₀ or +5° greater than that corresponding to P₀. In the population tested, it appears that "cross training" may alter the relationship between VO2SUB and HA's greater than that corresponding to P₀, thereby limiting comparison to a professional cyclist. The lack of significant differences between conditions indicates that the prediction algorithm created by Klippel and Heil (2001) may not be applicable to recreationally trained cyclists. According to the revised algorithm, a position that reduces TA, and therefore HA, results in a time trial position that maximizes ground speed for a majority of the collegiate cyclists tested.