【論文摘要】Effect of Fatigue on Reaction Time and Movement Time During Roundhouse Kick in Taekwondo Athletes

Abstract

Background and Purpose: Taekwondo (TKD) is a combat sport emphasizing sophisticated kick skills. A successful attack depends on a quick response and speedy movement, both probably affected by the accumulation of fatigue. Therefore, this study aims to investigate the effect of fatigue on the reaction time and movement time during roundhouse kick in TKD athletes. Methods: Six TKD athletes (age: 19.7 ± 1.4 years, height: 168.8 ± 9.2 cm, weight: 58.6 ± 5.2 kg, 3 females) were recruited and underwent a simulated game test. The simulated game test included three 2-minute rounds, with a 1-minute inter-round break. In each round, participants were asked to conduct 30 roundhouse kicks according to the instructions displayed on the screen, and the instructions included the standing pose (right or left lead), kick leg (front or rear), and kick position (high, middle, and low). Bilateral hip and knee angles were measured using 6 inertial measurement units placed over lower thorax, sacrum, bilateral thighs, and bilateral legs. Reaction time was the interval between the instruction showed up and the kick leg taking off. The chambering phase was the interval between the kick leg taking off and maximum knee flexion. The attacking phase was the interval between maximum knee flexion and target impact. An analysis of variance (ANOVA) with repeated measures was used to investigate the effect of fatigue (round 1, 2, and 3) and kick position (high, middle, and low) on reaction time, chambering phase, and attacking phase. Results: All participants completed the simulated game test. In reaction time, none of fatigue main effect, position main effect, and the interaction there between were significant. In chambering time, a significant fatigue-position interaction was found (F = 17.59, p ＜ 0.01). Post-hoc analysis showed that the chambering phase in high kicks during round 3 (0.49 ± 0.22 s) was significantly longer than that during round 1 (0.46 ± 0.18 s, p ＜ 0.01) and round 2 (0.47 ± 0.20 s, p = 0.02). In attacking phase, a significant fatigue main effect was found (F = 8.42, p = 0.04). Post-hoc analysis showed that the attacking time during round 3 (0.11 ± 0.04 s) was marginally longer than round 1 (0.09 ± 0.03 s, p = 0.05). Conclusion: Our results showed that the chambering phase that featuring a quick flexion of hip and knee, was substantially slowed down during the last round, especially in high kicks. This might result from the fatigue of hip flexors. Besides, the attacking phase featuring a quick extension of knee was marginally longer during the last round. This probably resulted from the fatigue of knee extensors. Clinical Relevance: This study offers TKD coaches and athletes an important insight into the design of training programs and combat strategies.