The Effect Of Cadence To Muscle Function Of Lower Extremity And Energy Consumption

Purposes:Based on the comprehensive research of surface electromyogram signal in muscles of lower limb and gas metabolic indices under different pedal frequency, Provide the theoretical and empirical basis for pedal frequency selection under the different competition requirements and objectives. Methods:Determine the max power and the cadence when the max power appears when the subjects who come from Beijing Sport University are under sitting position ride,see the cadence as reference point, and then divided into five frequency. The subjects ride 2 minutes remain stable in random cadence, real-time collect the surface electromyogram signal and gas metabolic indices, analyze the IEMG and MF. Amplitude-frequency conjoint analysis is used to observe the muscle activity, and combined with energy consumption and heart rate indexes for comprehensive analysis. Result:1 Between 7 gear gear, gear of 9 and 11 in SRM training system, the bigger the gear, the greater the max power and the cadence when appears the max power, and when they are in different gears and different cadences all have significant difference(P<0.05), and for the extremely significant difference(P<0.01). Fixed gear when the foot pedal, the greater the foot pedal frequency, the greater the foot pedal speed; Different gear when the foot pedal, when foot pedal percentage is consistent, the bigger the gear, the lower the cadence, the faster the speed. The cadence and the speed in different gears and different cadences when cycling all have significant difference(P<0.05), and for the extremely significant difference(P<0.01).2 In 7 gear gear, gear of 9 and 11, the integrated EMG rise with the increase of the foot pedal frequency, Most muscle integral value above the cadence when appear the max power in 7gaer is significantly higher than 9 gear and 11 gear. Most muscles median frequency decrease with the increase of the gear, but the significant change of proportion is less. The integrated EMG of Vastus lateralis muscle and the median frequency of Vastus lateralis muscle and gastrocnemius medial in cadences all have significant difference(P<0.05). Part of the muscle fatigue during 7 gear in the cadence when max power appears, 9 gear in the 60% and 140% cadence and 11 gear in the 60% cadence when max power appears.3 Energy consumption and heart rate in 7 gear, gear of 9 and 11 gear is linearly increased with the increase of foot pedal frequency, and has a very significant difference(P < 0.01),and during different cadence in different gears, 9 gear energy consumption and heart rate showed the lowest in the cadence when max power appears. Conclusion:1 The greater the gear, the smaller the maximum power and maximum power frequency which the subjects can achieve.2 With the cadence increase, muscle force increase; and energy consumption and heart rate are rising which have significant difference.3 Small transmission ratio(7 gear) can get better output power and larger muscle strength, and with the advantages of relatively small energy consumption and heart rate when use the cadence less than the cadence when appear the max power, but when greater than the cadence, the energy consumption and heart rate all have a higher, and body load has increased dramatically; Big transmission ratio(11 gear) can get faster speed,but it has a relatively small output power and the muscle is easy to fatigue, and the energy consumption and heart rate all have a higher and great body load; Medium transmission ratio(9 gear) had better comprehensive benefits, although the output power is less than small transmission ratio(7 gear), it had lower energy consumption and heart rate and smaller body load when under different pedal cadence. Suggestion:When select low gear ratio, it’s better to choose the cadence which near by the cadence that when the max power appears,which can get larger muscle force and relatively small energy consumption; When select high gear ratio, can get faster speed, but easy fatigue, so it is appropriate under the condition of physical ability better choose when to maintain a high speed.When use lager cadence to keep higher speed, it is better to select medium transmission ratio.So when the actual training game,to comprehensive transmission ratio and training requirements.