Comparisons of countermovement jump and isokinetic performance in youth athletes: maturation and early sport specialization considerations

Hofmann, C 2022, Comparisons of countermovement jump and isokinetic performance in youth athletes: maturation and early sport specialization considerations , PhD thesis, University of Salford.

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This thesis examines the impact of maturation status and single versus multiple sport participation on the physical performance of adolescent athletes across 6 studies. Study 1 investigated the test – retest reliability of isokinetic knee flexion and extension, countermovement jump (CMJ)performance and muscle architecture in adolescents. Eight ultrasound variables, nine CMJ variables and six isokinetic variables were found to be reliable among this subject group and were subsequently used in the remaining studies. Study 2 investigated the relationships between isokinetic knee flexor and extensor peak torques, muscle architecture and CMJ performance in adolescent athletes. The results showed that there were moderate to strong correlations between vastus lateralis muscle thickness and knee extension peak torque at 60°·s-1 and 300°·s-1 and CMJ height and its determinants (i.e., take-off velocity, propulsion impulse) mean and peak propulsion power, mean and peak propulsion force, mean and peak braking force. Before examining the impact of maturation and sport specialization on physical performance a defined method to establish peak height velocity (PHV) was required (study 3). Using a group (n = 65) of adolescent subjects PHV somatic measurement methods were compared. The results indicated that the equations for PHV estimates in males cannot be used interchangeably and for females even though no statistically significant differences were observed there was a large mean difference between the ages calculated by the different PHV equations. Therefore, practitioners should use consistent methods and only make comparisons with literature that uses the same equation. Study 4 compared isokinetic peak torque and CMJ variables between athletes of different peak height velocity stages using the Mirwald equation (2002). The results showed adolescents that are post-PHV perform better than the subjects that are pre or circa-PHV. Study 5 compared isokinetic peak torque and CMJ performance between average and late maturers based on the Mirwald equation (2002). The results indicate no significant or meaningful differences between the subjects that are classified as average maturers to those that are considered late maturers. The final study (study 6) evaluated subjects based on if they participated in one or multiple sports throughout the year. Subjects that were single sport athletes significantly and meaningfully outperformed multi-sport athletes in the CMJ and isokinetic performance variables. The results of this thesis show that maturation timing as well as participating in a single sport have an impact on how an athlete performs while completing countermovement jumps and isokinetic dynamometer testing. Since most current research concludes that being a single sport athlete leads to negative affects more research needs to be completed since in this study the subjects did outperform the multiple sport athletes. Future research should examine more performance variables to understand the effects of single versus multiple sport participation as adolescents transition through their maturation in order to make it the safest, healthiest and most beneficial transition.

Item Type: Thesis (PhD)
Contributors: Comfort, P (Supervisor)
Schools: Schools > School of Health and Society
Depositing User: Candice Hofmann
Date Deposited: 02 Feb 2023 11:35
Last Modified: 02 Mar 2023 02:30

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