Comparative Study On The Instant Effect Of Squat Jump With Different Load And Heavy Load Squat On Explosive Power

Objectives:the purpose of this study is to measure jumping height,take-off time,power,reactive strength index,impulse and average power these five different index to explore the changes of lower limbs explosive power after the squat and squat jump with different loads instantly and differences between the changes of collection of the subjects by three ways to intervene when muscle EMG amplitude to obtain discharge size and raise degree,bounce power mainly to explore the lower limb muscle group in the activation of various activation methods,and analyze the associations between different indicators and changes.Methods:A three-dimensional force measuring platform was used to collect the CMJ take-off kinetic indexes of subjects before and after intervention for 15s,2min,4min,8min,12min and 16min,and obtain the CMJ kinetic indexes under the condition of 10%body weight,30%MVC,90%1RM or no intervention,respectively.The EMG signals were collected under 10%body weight,30%MVC and 90%1RM load.Results:(1)The jump height of each group was changed as follows:compared with the non-intervention group,the increase of the three intervention groups was significantly increased(P<0.05),but there was no significant difference in the increase rate of the three intervention methods at each time point(P>0.05).(2)The variation of the take-off time of each group was as follows:there were significant differences between the 10%BW weight squat jumping group and the 90%1RM weight squat group and the intervention group(P<0.05),while there were no significant differences between the 30%MVC squat jumping group and the intervention group at each time point.The increment of take-off time of 10%BW squat was significantly higher than that of 30%MVC squat(P<0.05).(3)The changes of reactive strength index in each group were as follows:the increase of intervention means in the three groups was significantly different from that in the non-intervention group(P<0.05).At 15s,the RSI increase rate of 10%BW negative recombination was significantly higher than that of 30%MVC group(P<0.01),but there was no significant difference in the RSI increase rate of the three weight-bearing interventions at other time points(P>0.05).(4)Impulse changes in each group were as follows:Impulse under intervention increased in all three groups and significantly increased compared with non-intervention group(P<0.05),and there was no significant difference in the amplitude of the three weight-bearing intervention methods at each time point(P>0.05).(5)The changes of average power in each group were as follows:the increment of the three groups was significantly increased compared with the non-intervention group,and there was no significant difference in the increment of the intervention groups at each time point(P>0.05).(6)The changes of EMG in each group were as follows:10%BW squat jump stimulated the rectus femoris muscle,medial femoris muscle,semitendinosus muscle and biceps femoris muscle to the greatest extent;30%MVC squat can stimulate the gastrocnemius and vastus lateralis muscle the most.The 90%1RM squat stimulated the gluteus maximus and the tibialis anterior muscle the most.Conclusion:(1)In the aspect of improving the jumping height,the enhancement effect of 10%BW squat jump is faster but the duration is shorter,and the optimal time is 2min.The effect of 30%and 90%enhancement is slower but lasts longer,and the optimal time is 4min.(2)In terms of reducing the take-off and generating time,10%loading has the best effect,PAP is produced quickly and lasts for a long time,and the best time is 2min;90%effect followed,and the best time was 4min.30%MVC does not reduce take-off power generation time.(3)In terms of improving reactive strength,10%BW squat is the best,30%MVC squat and 90%1RM squat are the next.In the aspect of lifting impulse,30%MVC squat jump has the best effect,the largest improvement range and the longest duration.The use of 10%BW squat jump has the fastest speed,the best range and the longest time to improve the average power,followed by 90%1RM squat and 30%MVC squat jump.(5)Different intervention methods have different activation conditions for different muscles,but the activation effect of squat jumping on take-off force muscles is better than that of squat jumping.