Study On The Myoelectricity And Joint Angle Of Lower Extremity Muscles In Different Seat Height Of A Bicycle

Research purposes:By analyzing the dynamic changes of EMG and joint angle of the muscle surface of the lower limb of the human body,we can provide the basis for choosing the proper height of the pedestal.Object: Sichuan Normal University students 16 people,male and female 8 people(age 23.25±2.24,height 169.62±8.48,weight 62.87±9.16).Methods: Surface electromyography and three-dimensional motion capture were used to study the effect of different height on the level of muscle discharge and joint angle of lower limbs.With 3 seat heights(91% legs long,95% legs long and 99% legs long)for the study variable,let the athlete on the Power bicycle at 50 rpm speed Cycling,exercise load: Start cycling with 50 W power,and then increase the 50 W power every 3minutes until the exhaustion(heart rate reached 90% maximum heart rate)until.Test process: Each subject to undergo three tests,each test requires more than two days interval,each test before the use of 50 rpm rpm,the frequency warm-up 5 minutes,and then the formal test.For each test,use the surface EMG Tester(Noraxon/desktop DTS)to capture the right lower extremity gluteus maximus(Gluteus maximus),femoral two(biceps femoris),and rectus(rectus femoris,),EMG(Vatsus lateralis),gastrocnemius muscle(gastrocnemius),tibial anterior muscle(tibialis anterior),using infrared three-dimensional motion analysis software(Vicon Nexus 2.3)to collect the hip,Knee and ankle angle data.Results: The integral EMG values of the muscles were as follows: The iemg>muscle of the anterior tibial muscle iemg> The femoral rectus iemg> gastrocnemius iemg> femoral two muscle iemg> gluteal muscle iemg.The increase of pedestal height had no significant difference in the mean value of the integral electromyography ofGluteus maximus,and showed the regularity of decreasing first and then increasing.When the seat was elevated to 95%,the integral EMG values of the muscles were generally minimized.With the increase of riding power,the integral EMG value of each muscle showed a positive increasing trend,and the increase of the integral EMG of each muscle increased significantly with the 150 W to 200 W,and there was significant difference between each load.In the three seats of this experiment,the activity range of the hip is between 13° and 70°,the activity range of the knee is between 67° and 165°,the range of ankle activity is between 68° and 116°.Conclusion: 1.When the height of the pedestal rises gradually,the trend of the integral electromyography of each muscle is basically consistent,it is the first to decrease and then increase,the height of the lower limb is too high or too low,and the discharge of partial muscles is too large,which leads to muscle fatigue easily.2,95%High riding the main force of the muscle discharge is relatively small,is the ideal riding seat height.3,cycling in the course of the hip joint activity range between 13° to 70°,the range of activities of the knee between 67° to 165°,the range of activities of the ankle between 68° and 116°,so in the lower limb strength training,you can choose multiple joints angle to practice.