Association between Concentric and Eccentric Isokinetic Torque and Unilateral Countermovement Jump Variables in Professional Soccer Players

Abstract

Isokinetic tests have been highly valuable to athletic analysis, but their cost and technical operation turn them inaccessible. The purpose of this study was to verify the correlation between unilateral countermovement jump variables and isokinetic data. Thirty-two male professional soccer players were subjected to the isokinetic testing of both knee extensors and flexors in concentric and eccentric muscle contractions. They also executed unilateral countermovement vertical jumps (UCMJ) to compare maximum height, ground reaction force, and impulse power with isokinetic peak torque. Data analysis was conducted through Pearson correlation and linear regression. A high correlation was found between dominant unilateral extensor concentric peak torque and the UCMJ maximum height of the dominant leg. The non-dominant leg jump showed a moderate correlation. No other variable showed statistical significance. Linear regression allowed the generation of two formulae to estimate the peak torque from UCMJ for dominant and non-dominant legs. Although few studies were found to compare our results, leading to more studies being needed, a better understanding of the unilateral countermovement jump may be used in the future as a substitute to the expensive and technically demanding isokinetic testing when it is unavailable, allowing the assessment of lower limb physical asymmetries in athletic or rehabilitation environments.

Relationship between unilateral and bilateral countermovement jump performance and force-velocity-power outcome variables

“…However, it was recently proposed that the two-point method is a reliable and valid procedure to determine the individual F-v-P profile from a vertical jump (García-Ramos, Pérez-Castilla, & Jaric, 2021). A linear regression model is typically applied to the recorded force concentric peak torque of knee extensors (Alves, et al, 2022;Fischer, et al, 2017). The reasons for lower force produced bilaterally are due to a reduced neural drive (Škarabot, Cronin, Strojnik, & Avela, 2016).…”

“…The fact that a higher UCMJ height strongly correlates to the knee extensors' strength (Alves, et al, 2022), guided us to the hypothesis that F-v-P outcome variables may be predicted through unilateral and bilateral CMJ performance. We aimed to mimic the concept of the two-point method by utilizing BCMJ and UCMJ force and velocity conditions to map the entire F-v-P spectrum.…”