Are isokinetic leg torques and kick velocity reliable predictors of competitive level in taekwondo athletes?

Author(s)

Sarmet Moreira, Pedro Vieira ^{[1, 2, 3]} ; Falco, Coral ^[4] ; Menegaldo, Luciano Luporini ^[1] ; Goethel, Marcio Fagundes ^[2] ; de Paula, Leandro Vinhas ^[5] ; Goncalves, Mauro ^[2]

Affiliation

^[1] Univ Fed Rio de Janeiro, Biomed Engn Program, COPPE, Rio De Janeiro, RJ - Brazil

^[2] Sao Paulo State Univ UNESP, Lab Biomech, Rio Claro, SP - Brazil

^[3] Tech4Fight Sports Technol, Rio De Janeiro, RJ - Brazil

^[4] Western Norway Univ Appl Sci, Dept Sport Food & Nat Sci, Bergen - Norway

^[5] Univ Fed Minas Gerais, Lab Biomech, Belo Horizonte, MG - Brazil

• Document type: Journal article
• Source: PLoS One; v. 16, n. 6 JUN 9 2021.
• Web of Science Citations: 0

Abstract

The aim of this study is to analyze how isokinetic knee and hip peak torques and roundhouse kick velocities are related to expertise level (elite vs. sub-elite) in taekwondo athletes. Seven elite and seven sub-elite athletes were tested for kick-specific variables (KSV, composed of kinematic variables and power of impact) and for concentric isokinetic peak torque (PT) at 60 degrees /s and 240 degrees /s. First, KSVs and PTs were compared between groups, then PTs were correlated with KSVs. Parametric variables with larger effect sizes (Cohen's d) were entered in a stepwise linear discriminant analysis (LDA), generating an equation to estimate competitive level. Between-group differences were found in hip flexors (p = 0.04, d = 0.92) and extensors (p = 0.04, d = 0.96) with PT at 240 degrees /s. Hip flexion PT at 60 degrees /s and 240 degrees /s correlated negatively with kick time (R = -0.46, p = 0.0499 and R = -0.62, p = 0.01 respectively). Hip flexion torque at 60 degrees /s correlated positively (R = 0.52, p = 0.03) with peak linear velocity of the foot (LVF) and power of impact (R = 0.51, p = 0.03). Peak torque of hip extension at 60 degrees /s and hip abduction at 240 degrees /s also correlated with LVF (R = 0.56, p = 0.02 and R = 0.46, p = 0.0499). Hip extension at 60 degrees /s correlated positively with peak linear velocity of the knee (R = 0.48, p = 0.04). The LDA showed an accuracy of 85.7% (p = 0.003) in predicting expertise level based on hip flexion and extension torques at 240 degrees /s and on knee extension velocity during the kick. The study demonstrates that hip muscle strength is probably the dominant muscular factor for determining kick performance. Knee angular velocity combined with hip torques is the best discriminator for competitive level in taekwondo athletes. (AU)

• FAPESP's process: 12/19093-6 - Neuromuscular and kinematic parameters of performance in Taekwondo kick
• Grantee: Pedro Vieira Sarmet Moreira
• Support Opportunities: Scholarships in Brazil - Doctorate