Objective To compare the influence of step frequency change on the impact force and kine-matic parameters of lower limbs of college students when running at the same speed and with different step frequency so as to provide reference for college students to make a reasonable running plan.Methods In this study,15 male college students majoring in physical education were randomly selected to run at the same speed(9 km/h)on a treadmill at high step frequency(190 steps/min),medium step frequency(170 steps/min),and low step frequency(150 steps/min),respectively.A 1 000 Hz three-dimensional force measuring table and a 200 Hz infrared motion capture system were used to collect the impact force on the lower limbs and kinematic parameters of each joint of the lower limbs during the running process.Results With the increase of step frequency,the first and second peak forces of the subjects'vertical ground force decreased gradually,with significant differences(P<0.05).The first peak value and the second peak value of impact load ratio decreased gradually,and there was a very significant difference(P<0.01).At the moment of landing,the knee joint torque decreased with the increase of step frequency,and the moment of ankle joint and hip joint increased with the increase of step frequency(P<0.05).However,the knee joint torque and hip joint torque did not change significantly with the increase of step frequency(P>0.05).At the moment of landing,the angle of ankle joint decreased gradually while the angle of knee joint increased gradually,and the angle of flexion extension and adduction and abduction of hip joint increased gradually,with significant differences(P<0.05).At the time of lifting off the ground,the angle of ankle inversion and ectropion and internal and external rotation gradually decreased,the passive adduction and abduction angle of knee joint gradually increased,and the angle of internal and external rotation of hip joint gradually decreased,with significant differences(P<0.05).During the peri-od of support,the movement amplitude of ankle joint and knee joint decreased gradually,with a significant difference(P<0.05).Conclusion Appropriate increase of step frequency is helpful for reducing the impact force and energy loss of lower limbs,reducing the risk of sports-induced injury,improving the kine-matic parameters during running,and improving the efficiency and comfort of running.
维普
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