A Study On The Surface Electromyographic Characteristics And Subjective Fatigue Perception Of Lower Limb Muscles In Weight-bearing Deep Squats With Different Movement Rhythms

Objective:This study combines the objective surface electromyographic characteristics and the subjective fatigue perception of the subjects to illustrate the stimulation effect of weighted squats on the muscles of the lower extremities from different angles,and to compare and analyze the root mean square amplitude,muscle contribution rate and subjective fatigue perception indexes of the muscles of the lower extremities of weighted squats with different movement rhythms.The study also explored the corresponding rules of lower extremity muscle stimulation,provided reference for the selection of different squatting rhythms in training practice,further improved the refinement level of resistance training control,and provided theoretical and practical reference for the selection of lower extremity strength training methods and means.Methods:Using a combination of literature,expert interviews,experimental methods,mathematical statistics and logical analysis,20 healthy male college students with solid weight-bearing deep squatting techniques were recruited and screened at Shandong Institute of Physical Education（Jinan Campus）.The mean square root amplitudes of the gluteus maximus（GM）,vastus medialis（VM）,vastus lateralis（VL）,rectus femoris（RF）,biceps femoris（BF）,semitendinosus（ST）,medial head of gastrocnemius（MG）,lateral head of gastrocnemius（LG）,and the lateral head of gastrocnemius（MG）were compared and analyzed using the Noraxon surface EMG tester,MR3.0,and Spss25.0 software to study the effect of the weighted squat on the movement rhythm T₁（5/0/2/0）,T₂（5/0/5/0）,T₃（2/0/2/0）,and T₄（2/0/5/0）,root mean square amplitude values（RMS）,muscle contribution,and subjective fatigue perception.Results:（1）The EMG signal in the centrifugal phase under the same external load was generally lower than in the centripetal action phase;the contractile mechanism of the muscle in the slower-paced centrifugal phase preactivated the muscle and increased force production,with higher levels of muscle activation and greater variation in the resulting EMG amplitude.（2）There was no significant effect（P>0.05）on the muscle contribution of gluteus maximus,vastus medialis,vastus lateralis,rectus femoris,biceps femoris,and semitendinosus during weighted deep squats with four movement rhythms;the muscle contribution of gastrocnemius was significantly higher in T3（2/0/2/0）rhythm than in T1（5/0/2/0）and T2（5/0/5/0）.（3）There were no significant differences in subjective fatigue perceptions during the subjects’four movement rhythms of weighted deep squats（P>0.05）.Conclusions:（1）The four movement rhythms had no significant effect（p>0.05）on the root mean square amplitude values of the gluteus maximus,medial femur,lateral femur,rectus femoris,biceps femoris,semitendinosus,medial head of gastrocnemius,and lateral head of gastrocnemius during weighted deep squats in the subjects.According to the trend of amplitude change corresponding muscles were more activated by centrifugal training than centripetal training muscles.（2）The gastrocnemius is best stimulated in fast-paced weighted squats;you can speed up the tempo of movement in strength training for the gastrocnemius.（3）In the actual training to choose a comprehensive rhythm of movements to prevent monotonous training or over-training.