| The bicycle sport,as an important part of athletic sports,is an Olympic item.Chinese athletes have not gained too much achievements on it.There is still a research gap between China and the developed countries.Therefore,this thesis tries to improve Chinese bicycle sport through the research of seat height.Purposes:Choosing suitable seat height for cyclists according to their morphologic characteristics and analyzing their technique.Objects and Methods:15 male trained cyclists[19±2 years]were tested at three seat heights(91%,95%and 99%greater trochanteric height) with their own bicycles on the roller.Rode at each height for 40s with the intensity corresponding to the velocity in game.The sEMG activity was recorded from the gluteus maximus,biceps femoris,rectus femoris,vastus lateralis, gastrocnemius and tibialis anterior in the right lower limb while subjects were performing the bicycle movements.Kinematic data was collected at the same time.Results:1.Vastus lateralis and biceps femoris played more important role in pedaling.Anincrease of the seat height increased the muscle activity in the biceps femoris,gastrocnemius and tibialis anterior but decreased the muscle activity in the gluteus maximus,rectus femoris and vastus lateralis.The sEMG will be great if the seat height is too high or too low.2.The starting point of sEMG activity of extensors delayed with the seat height raised.Resulted in the muscle activity range becaming more coincident with the range of pedal and it made for improving pedaling efficiency.3.The seat height that equals to 95%greater trochanteric height was more suitable to the cyclists in this research.4.The working phase of lower limb muscles was the main factor which influenced the technique of straight pedal on flat ground.5.In the speed of 48km/h,the angle velocity of hip-joint and knee-joint was 180°/s and 300°/s respectively.The range of motion of hip-joint,knee-joint and ankle-angle was 60°to 90°,60°to 130°and 80°to 120°respectively.
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