Changes in human cervical and lumbar spine curves while bicycling with different handlebar heights.

Cycling is a daily activity that needs a high demand of human-bicycle fitness. However, studies into the fitness or ergonomic aspects are very little. In this study, the simulated 20 min bicycling test were performed by 26 male participants under 5 handle height conditions. Body joint angles and external cervical/lumbar spine lordosis were measured at the initial and cycling after 20 min. Results show that different handle heights did cause various trunk inclinations. Trunk inclination was negatively and positively correlated with lumbosacral angle (r = -0.620, p < 0.001) and cervical angle (r = 0.510, p < 0.001), respectively. In this study, regression models were also developed to predict the internal cervical and lumbar spine movements by external trunk inclination and head extension, respectively. The explanatory abilities for the variance of the models were 67.2% for LSA and 82.8% for CE prediction. This can be used to understand the cyclist's spine movements while field study of bicycling.