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

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°/s and 240°/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°/s. Hip flexion PT at 60°/s and 240°/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°/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°/s and hip abduction at 240°/s also correlated with LVF (R = 0.56, p = 0.02 and R = 0.46, p = 0.0499). Hip extension at 60°/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°/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.

Using an artificial neural network to develop an optimal model of straight punch in boxing and training in punch techniques based on this model and real-time feedback

“…Thus, the feedback technique showed high efficiency. This is in good agreement with the work [ 4 ], which describes the use of biofeedback in sports shooting. Feed-back in the work [ 4 ] was made using error recognition based on machine learning and led to an increase in shooting accuracy and a shorter training period.…”

“…A similar approach was applied in a very interesting work [ 4 ], the purpose of which was to determine the level of readiness for the kinematic parameters of the kick of 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 0 / s and 240 0 / s .…”

Comparison of bilateral isokinetic and isometric strength differences in elite young male and female taekwondo athletes

“…Although taekwondo athletes are supposed to achieve scores by using both legs during matches, they prefer to use their dominant leg in practice for a more effective kick, since as a result of chronic repetition, there is a strength increase in favor of the dominant leg, which makes the athlete more vulnerable to injuries due to the increasing strength difference between dominant and nondominant legs ( Croisier et al, 2008 ). On the other hand, stronger limbs may be more advantageous in generating higher scores as they have a greater impact in kicking techniques ( Moreira et al, 2021 ). As a result, assessment of the isokinetic strength difference between legs in elite youth taekwondo athletes may help to prevent injuries and to develop training programs.…”

Effect of Post-Activation Potentiation according to Sequence of Velocity Using Isokinetic Device on Short-Term Performance of Lower Extremity: Taekwondo Athletes and Healthy Adults

“…Therefore, player focus to improve the speed and power of kick during training session. 2,3 To make one's kick faster and powerful, a few factors such as hip, knee might be considered. 3 Among all these factors, we focused on structures which is related with knee extension.…”

“…2,3 To make one's kick faster and powerful, a few factors such as hip, knee might be considered. 3 Among all these factors, we focused on structures which is related with knee extension. A typical muscle that affects knee extension is the quadriceps femoris.…”