Effect of gradient on cycling gross efficiency and technique

Purpose: The purpose of this study was to determine the effect of gradient on cycling gross efficiency and pedaling technique. Methods: Eighteen trained cyclists were tested for efficiency, index of pedal force effectiveness (IFE), distribution of power production during the pedal revolution (dead center size [DC]), and timing and level of muscle activity of eight leg muscles. Cycling was performed on a treadmill at gradients of 0% (level), 4%, and 8%, each at three different cadences (60, 75, and 90 rev·min^-1). Results: Efficiency was significantly decreased at a gradient of 8% compared with both 0% and 4% (P < 0.05). The relationship between cadence and efficiency was not changed by gradient (P > 0.05). At a gradient of 8%, there was a larger IFE between 45 and 225 and larger DC, compared with 0% and 4% (P < 0.05). The onset of muscle activity for vastus lateralis, vastus medialis, gastrocnemius lateralis, and gastrocnemius medialis occurred earlier with increasing gradient (all P < 0.05), whereas none of the muscles showed a change in offset (P > 0.05). Uphill cycling increased the overall muscle activity level (P < 0.05), mainly induced by increased calf muscle activity. Conclusions: These results suggest that uphill cycling decreases cycling gross efficiency and is associated with changes in pedaling technique.