The Isometric And Isotonic Barbell Back Squat Exercise's Effect On Strength Performance Of Lower Limb

Objective: This research aim to compare the isometric and isotonic barbell back squat exercise with the normal barbell back squat exercise's effect on the strength performance of lower limbs.This research wish to find a strength exercise that can combine the advantages of various muscle contraction forms,and provide certain theoretical reference for different individuals to choose the strength training method.Methods: In this research,the experimental method was mainly used,and the intergroup and intragroup mixed experiment design was adopted.The intergroup variables was training intervention,the intragroup variables was pre-test and posttest,and the dependent variables were muscle strength index.The subjects were 22 male students with basic strength training ability from Beijing sports university.This research's subjects was divided into experimental group and control group.This research did all index test before training intervention,and after the pre-test preliminary experiment was carried out to determine the training load.During the eight weeks of training intervention,the experimental group used isometric and isotonic barbell back squat exercises,and the control group used normal barbell back squat exercises.Doing each index test again after intervention.In the end,this research used independent sample t-test and paired sample t test for statistical indicators.Results :(1)The experimental group and the control group showed significant increases in 1RM squat,thigh girth,centripetal peak torque,centripetal muscle total work and centrifugal peak torque after the experiment(P < 0.05).(2)The experimental group's centrifugal muscle total work and standing long jump index showed significant increase after the experiment(P < 0.05),while the control group showed no significant difference after the experiment in these two index(P > 0.05).(3)There were significant differences between the experimental group and the control group in the changes of 1RM squat,standing long jump,thigh girth,centrifugal muscle total work and centripetal muscle total work before and after the experiment(P < 0.05),and the changes in the experimental group were greater than those in the control group.There was no significant difference between the experimental group and the control group in the changes of centripetal peak torque and centrifugal peak torque after the experiment(P > 0.05).Conclusion: After the analysis of the experimental data,the following conclusions can be drawn:(1)The training effect of the isometric and isotonic barbell back squat exercise is superior to that of the normal barbell back squat exercise in the maximum strength of the back squat,lower extremity explosive force and thigh muscle cross-sectional area.(2)The training effect of the isometric and isotonic barbell back squat exercise on the maximum strength of quadriceps knee extension has no significant difference compared with the normal barbell back squat exercise,and it is better than the normal barbell back squat exercise in the strength endurance of quadriceps knee extension.