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PHYSIOLOGICAL AREA   

Medicina dello Sport 2021 September;74(3):384-95

DOI: 10.23736/S0025-7826.21.03885-0

Copyright © 2021 EDIZIONI MINERVA MEDICA

language: English, Italian

Changes in isokinetic muscle strength of the knee in elite female adolescent volleyball players after 4 years of systematic training

Liang CHENG 1, Hanxiao XU 2, Benxiang HE 1, Jianan ZHOU 3

1 School of Sports Medicine and Health, Chengdu Sport University, Chengdu, China; 2 College of Physical Education, Chengdu University of TCM, Chengdu, China; 3 Sichuan Sports College, Chengdu, China


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BACKGROUND: There are few reports regarding changes in joint muscle strength in elite-level adolescent athletes after systematic training.
METHODS: This study followed elite-level adolescent female volleyball players for 4 years to analyze changes in knee joint muscle strength after systematic training. We performed isokinetic muscle strength testing of the knee at angular velocities of 60°/s and 240°/s in 16 elite-level adolescent female volleyball players.
RESULTS: Compared with baseline, in adulthood (4 years later), peak torque (240°/s) in the right flexor and extensor increased by 13.94% and 16.02% (P<0.05), but the increase was not statistically significant for the left knee (P>0.05). Left and right flexor endurance ratios increased by 17.00% and 14.75%, respectively (P<0.05). The difference between bilateral homonymous muscles was more than 15%, in adolescence, at 60°/s, N.=1 for flexors, N.=5 for extensors; at 240°/s, N.=2 for flexors, N.=4 for extensors and in adulthood, at 60°/s, N.=1 for flexors, N.=2 for extensors; at 240°/s N.=1 case for flexors, N.=3 for extensors.
CONCLUSIONS: After 4 years of systematic training, elite-level adolescent female volleyball players had significant increased (240°/s) peak torque for the dominant knee, and the endurance ratio of bilateral flexor muscles was improved. We recommend strengthening the knee flexor muscle group during training to increase hamstrings-to-quadriceps ratio values and reduce the risk of knee injury.


KEY WORDS: Female athletes; Adolescent; Knee; Volleyball; Muscle strength

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