The Characteristics Of Lower Limb Muscle Activation And Plantar Pressure In Cycling With Different Transmission Ratios

PurposeCycling event is an important part of Olympic Games.It is a question to all the coach and research that how to get excellent results in 2008. Driving cycle multiplied by cadence is the speed of bicycle.The driving cycle is the product of transmission ratio multiplied byπ.Crank inertial load is the direct proportion of transmission ratio's square. The driving cycle and crank inertial load are affected by the transmission ratio of bicycle.Although transmission is so important,there is little experimental study about it.So,in this study,4 different transmission ratios were chosen,to study the characteristics of power output,cadence, speed,sEMG of lower limbs and planar pressures in cycling,hoping to provide evidence for improving purposeful training in professional cyclists.MethodsEight competitive cyclists performed 4 trials with different transmission ratios on a bicycle equipped with a SRM crankset.They were 46/14,47/14,47/13,and 48/13.The power output,speed,cadence,sEMG of 14 muscles,the plantar pressure of both side were measured.Research the characteristics of power,cadence,sEMG curves and planar pressure curves.Results1.The power output was higher with the high transmission ratio(47/13, 48/13) compared with low transmission ration(46/14,47/13).The cadence was lower with the high transmission ratio.When they rode with 47/13, the cyclists' abilities of speed and strength could be performed fully. 2.Muscle activities were influenced by the crank inertial load and cadence which were affected by transmission ratio of the bicycle.The transmission ratio has little effect on the onset,duration and peak time of the muscle activities.TA had two peaks in one cycle.It acted at top dead center and bottom dead center,coordinating with other muscles to help the pedal passing the dead centers smoothly.RF,BF,and GAS were performed strongly when pedaling down,and did not performed positively when up.3.The peak planar pressure could be found after 90°.Compared with the right side,the peak pressures of the left were higher,and the angles were smaller.The curves of plantar pressure were similar with the sEMG curves.And the transmission ratio also has little effect on plantar pressure.Conclusion:The combine of power output,speed and cadence was optimal for these cyclists when the transmission ratio was 47/13,and the characteristic of plantar pressure was optimal,too.Cyclists could cycling with 46/14 and 46/14 to train the ability of speed.