Neuromuscular performance of Bandal Chagui: Comparison of subelite and elite taekwondo athletes

The Cognitive Function and Taekwondo-Specific Kick Performance of Taekwondo Athletes at Different Hydration Statuses

PURPOSE

Successful participation in taekwondo (TKD) requires athletes to possess quick decision-making abilities and demonstrate technical proficiency during competition. Dehydration, occurring during both training and competition, is widely recognized to have various negative effects.

METHODS

This study investigated the impact of different levels of dehydration on cognitive function, as measured by the Vienna Test System, and the specific performance of kicking techniques among TKD athletes. Using a randomized crossover design, 12 participants were involved in the study. Before and after 1 hour of training at 80% of maximal heart rate, participants were weighed and provided urine samples. All participants were randomly assigned to 3 different hydration conditions: the euhydrated (EUH) group had unrestricted access to fluid consumption, while the hypohydrated (HYP) and severely HYP (S-HYP) groups experienced reductions of 2.0% and 4.0% of their initial body weight, respectively.

RESULTS

The EUH group exhibited better reaction speed in reaction-time test-form S1 than the HYP and S-HYP groups. Notably, the EUH group demonstrated a significantly higher success rate in the front-side kick (EUH 98%, HYP 90%, S-HYP 88%; P < .05). However, the success rates of back roundhouse kick and free head kick were similar among the 3 statuses. Furthermore, postexercise heart rates were found to be significantly higher in the HYP and S-HYP groups compared with the EUH group.

CONCLUSIONS

This study provides insight into the negative effects of dehydration on cognitive function and TKD-specific performance. It is recommended that TKD athletes maintain optimal hydration levels during training and competition to ensure optimal performance.

The effects of pre-task music on choice visual reaction time in elite taekwondo athletes

OBJECTIVES

The effects of music on sport performance mainly involved endurance or resistance exercises overlooking possible effects on reaction time, which is deemed essential in martial arts for a proficient performance. Therefore, the aim of this study was to investigate the effects of the exposure to pre-task music on choice visual reaction time in elite taekwondo athletes.

DESIGN

Repeated measure study design.

METHODS

Reaction time and mean Heart Rate (HRmean) were recorded in twenty young taekwondo athletes (17.5 ± 2.5 years old) while performing a roundhouse kick in response to different visual stimuli after three warmup conditions: listening to self-selected music (SM), research-selected music (RM) or no music (CC). Moreover, Feeling Scale (FS), Felt Arousal Scale (FAS) were recorded before (T0) and after warmup (T1) in each testing session.

RESULTS

SM and RM elicited significantly faster reaction times compared to CC (-3.3 % and -5.2 %, respectively). No significant difference in reaction time was observed between SM and RM. The FS and FAS scores were significantly higher at T1 compared to T0 in the SM and RM conditions, whereas no difference between T0 and T1 was observed in the CC condition. No difference was observed for HRmean between SM, RM and CC conditions.

CONCLUSIONS

Listening to SM and RM during the warmup improved choice visual reaction times in elite taekwondo athletes. These results suggest the use of music as a performance-enhancing strategy prior to combat competition or training in martial arts.

Differences in kick-leg kinematics in various side-kick heights

This study aims to explore the variation of lower extremity kinematic characteristics when elite taekwondo athletes perform the side-kick on protective gear placed at various heights. Twenty distinguished male national athletes were recruited and were asked to kick targets at three different heights adjusted according to their body height. A three-dimensional (3D) motion capture system was used to collect kinematic data. Kinematic parameters differences in the side-kick at three different heights were analyzed by using a one-way ANOVA (p < .05). The results revealed significant differences in the peak linear velocities of the pelvis, hip, knee, ankle, and centre of gravity of the foot during the leg-lifting phase (p < .05). Significant differences between heights were noted in the maximum angle of pelvis left tilting and hip abduction in both phases. In addition, the maximum angular velocities of pelvis left tilting and hip internal rotation were only different in the leg-lifting phase. This study found that, to kick at a higher target, athletes increase the linear velocities of their pelvis and all lower extremity joints of attacking leg in the leg-lifting phase; however, they only increase rotational variables on the proximal segment at the peak angle of the pelvis (left tilting) and hip (abduction and internal rotation) in the same phase. As an application in actual competitions, according to the opponent's body height, athletes can adjust both linear and rotational velocities of their proximal segements (pelvis and hip) and deliver into distal segements (knee, ankle, foot) linear velocity to perform accurate and rapid kicks.

A kinematic model for assessment of hip joint range-of-motion in fast sport movements using spreading angles

The work investigates the relationship between the leg spread and hip joint flexibility during kicking action of highly skilled martial artists. Vector-based spreading angles (VSAs), as a simplified way to assess kick execution patterns and movement ranges, are proposed. The first VSA measures the angle between the two femur vectors (i.e., upper leg spread), whereas the second describes the full-leg spread. The proposed measures were applied to 3D motion analysis performed on 33 participants at various skill levels who executed double side kicks and performed two static flexibility tests (hip joint flexion and abduction). Statistical analysis showed that the proposed parameters differentiate between skill levels. Both VSAs and VSA rate of change showed high Pearson correlation to the quality of execution (the average of 10 subjective kickboxing experts' evaluation scores) at critical instants of the kick execution , i.e., during the first leg elevation and kick (angles: ρ > 0.8; p < 0.001). In addition, they significantly correlated to maximum static hip abduction at any instant (ρ = 0.37-0.69; p < 0.05). The work established that both static and dynamic joint flexibility contribute to high-performance levels and could be used for initial selection and assessment of training effectiveness.

Effect of foot orthoses on dynamic balance in taekwondo athletes with flexible flatfoot: A randomized controlled trial

BACKGROUND

Flexible flatfoot (FFF) cause biomechanical and sensorimotor disorders of the foot and ankle complex and reduce of postural stability. Postural stability is an important movement skill that affects the performance of taekwondo (TKD) athletes and can lead to fall injuries. The purpose of this study is the effect 12-week application of foot orthosis (FOs) on dynamic balance in TKD athletes with FFF.

METHOD

In this trial, 30 girls of the TKD athletes with FFF were recruited. They were randomly assigned to experimental and control groups (15 subjects in each group). The experimental group used FOs with medial longitudinal arch support for 12 weeks, and the control group did not have any intervention. The outcome measures include navicular drop and balance in three directions: anterior-posterior, medial-lateral and overall stability. Covariance analysis was used to compare the results between two groups.

RESULTS

The covariance results showed that the experimental group compared to the control group with a high effect size had a significant difference in reducing of navicular drop (P = 0.000, ηp2 =0.512), anterior-posterior sway (P = 0.000, (ηp2 =0.397) medial-lateral sway (P = 0.019, ηp2 = 0.186) and overall stability sway (P = 0.008, ηp2 = 0.232).

CONCLUSIONS

The FOs with medial longitudinal arch support leads to FFF correction and provides mechanical stability of the foot and ankle complex. Also, the impulses sent from plantar receptors are increased and a better understanding of postural sway is transmitted to the central nervous system and balance strategies are improved.

Comparisons of musculoskeletal injuries among three different modalities of Taekwondo (Kyorugi, Poomsae, and Shibum): a one-year follow-up prospective epidemiologic study

The purpose of the study was to report the injury rates and characteristics (body location, type, mechanism, and severity) of musculoskeletal injuries in Kyorugi, Poomsae, and Shibum. A total of 137 Korean collegiate Taekwondo players - Kyorugi (n = 44), Poomsae (n = 46), and Shibum (n = 47) - were prospectively studied in 2019. Injury rates per 1,000 athlete-exposures (AEs) and time-exposures (TEs) during training and competition were calculated. Additionally, body location, type, mechanism, and severity of injury were analysed. The highest injury rate was recorded in Poomsae (172.0/1,000 AEs and 79.5/1,000 TEs) followed by Kyorugi (47.1/1,000 AEs and 25.9/1,000 TEs) and Shibum (57.5/1,000 AEs and 17.0/1,000 TEs). The frequently injured body location was the thigh (Kyorugi = 17%; Poomsae = 25%; Shibum = 18%). The common injury types were muscle cramps/spasms in Kyorugi (33%) and Poomsae (59%), and sprain in Shibum (41%). The common injury mechanisms were gradual onset in Kyorugi (40%) and Shibum (49%), and non-contact trauma in Poomsae (91%). Regarding the severity, the number of days from the injury onset to recovery > 1 week were higher in the order of Kyorugi (78%), Shibum (54%), and Poomsae (28%). Our data provide preliminary evidence that different injury prevention strategies should be applied to each modality of Taekwondo.

Differences in Velocities of Crucial Body Segments while Executing Roundhouse Kicks for Both Sides

Lower limb kinematics of the roundhouse kick is a well-known topic studied by many researchers. However, there is a lack of data about the velocity of the core and upper limbs during the execution of this technique. The aim of this study was to evaluate the differences in velocities of all crucial body segments while executing roundhouse kicks for both sides of the body. Thirteen elite taekwon-do athletes participated in this study. They performed kicks to a table tennis ball three times using each leg. The spatial-temporal data of markers placed on toes, knees, hips, shoulders, elbows, hands, and sternum were captured with the use of the Human Motion Lab equipment composed of 10 infrared cameras NIR Vicon MX-T40. There were statistical differences in the maximal velocity of the sternum and opposite shoulder. There were different correlations between the time of acquiring maximal velocities of specific body segments and the maximal velocity of the toe marker for each kicking side. Higher correlations were observed for the left kick despite the participant’s declaration of their preference for the right leg. The obtained results facilitate the conclusion that small non-resistant targets require different motor control depending on the kicking side, despite not revealing significant differences between maximal velocity. While such an indicator could be perceived as a suitable benchmark of an athlete’s performance, more detailed analysis seems to be required for a better understanding of martial arts techniques.

Kinematic and kinetic demands on better roundhouse kick performances

The roundhouse kick is one of the most widely applied techniques in a taekwondo competition. Because the scoring system of taekwondo has been changed, the skill of roundhouse kick has been affected. Therefore, coaches and athletes are attempting to better understand how to control the movement of the kick to gain points more effectively. The aim of this study was to investigate the differences in the biomechanical characteristics between the roundhouse kicks with higher and lower impact magnitude using an electronic body protector. Eighteen elite college Taekwondo athletes participated in this study. A motion capture system measured the kinematics data of the kicking leg. The results indicated that elite athletes can obtain a high-impact index of the electrical body protector through increasing the peak linear velocity of shank, even with the same foot velocity level. In regard to kinetic skills, the roundhouse kicks a high impact. The velocity of proximal kicking limb could predominantly contribute to the powerful roundhouse kicks to achieve the high-impact force for electrical body protector. Moreover, when the kick cannot be effectively scored during the game, coaches and masters should consider adjusting to increase the velocity of proximal kicking.

Muscle Contraction Adaptations in Top-Level Karate Athletes Assessed by Tensiomyography

BACKGROUND

This paper aimed to compare the involuntary stimulated neuromuscular response of thigh muscles in top-level karate athletes and recreational groups.

METHODS

The study included 13 male karate athletes (KAs) and 14 non-athlete male individuals (NAs). Tensiomyographic (TMG) measurements were obtained from the rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF) and semitendinosus (ST).

RESULTS

Statistically significant differences were observed between KAs and NAs in knee extensor/flexor delay time (Td), contraction time (Tc), total contraction time (Tct), maximal radial displacement of the muscle belly (Dm) and rate of muscle tension development (RMTD). On a group level, KA dominant-leg extensors and flexors and also non-dominant-leg knee flexors had significant differences when compared to NA. Tct is a TMG parameter in which the KAs and NAs differ the most in the case of the knee extensors, while flexor muscles differ the most in the RMTD parameter.

CONCLUSIONS

The lower Tct values indicate an improved ability of top-level karateka to make fast contractions of the agonist muscles. KAs' higher RMTD values suggest on strength characteristics needed in breaking actions of the antagonist muscles. Existence of contraction-relaxation-contraction neuromuscular pattern in the RF muscle suggests on implementation of training strategies that involves both rapid muscle contractions and relaxations.

Kinematic Effects of the Target on the Velocity of Taekwon-Do Roundhouse Kicks

The phenomena of target kinematic effects under different striking conditions and applying different techniques constitute one of the fields of research for sports biomechanics. However, the influence of some kinematic variables which change under different strike conditions for specific parts of the lower limb remains unknown. The aim of this study was to extend the knowledge on how targets of different shapes or the lack of a physical target would affect maximal velocity registered by a marker placed on the foot, knee and hip during the execution of a roundhouse kick. In total, 15 adult males were included in this study. All participants were taekwon-do elite athletes. The displacement of markers placed on the lateral side of the foot, knee and hip during movement execution was registered by a stereophotogrammetry apparatus. Participants performed taekwon-do roundhouse kicks for three target types (into the air, a table tennis ball and a training shield) applying either a sport or a traditional style. The highest maximal velocity was obtained for kicking into the training shield. When applying the sport style, the highest maximal velocity of foot markers for the executed kicks was registered. Kicking into air resulted in higher velocities for proximal body parts than kicking into a tennis ball, but the effect was reversed for the foot marker. In conclusion, a large resistance target is suitable for athletes' motor preparation as it allows the highest maximum velocity to be reached. Small non-resistant targets are recommended for technical training.

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

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.

Reaction time and muscle activation patterns in elite and novice athletes performing a taekwondo kick

Fractionated reaction time can be used to determine distinct epochs known as pre-motor, response and movement times (MTs) of a reaction time task. The purpose of this study was to compare elite and novice athletes performing a taekwondo kick in terms of the fractionated reaction time and electromyography (EMG) activation patterns of the muscles of the striking lower limb and the lower back. We hypothesised that the pre-motor time, response time (RT) and MT would be the shorter for elite athletes compared to novices. We collected data on 13 elite and 10 novice athletes when performing a roundhouse kick. The experiment included EMG electrodes placed on five low back and lower extremity muscles and an electrogoniometer placed on the kicking knee. We found that pre-motor time was shorter and the RT was longer for elite athletes than novice athletes. Moreover, the integrated EMG of the main knee extensor does not differ between groups though other leg and trunk muscles do. The results allow coaches and teachers to understand this particular taekwondo kicking movement which could ultimately improve the technique in order to establish training and teaching goals.

Human Actions Analysis: Templates Generation, Matching and Visualization Applied to Motion Capture of Highly-Skilled Karate Athletes

The aim of this paper is to propose and evaluate the novel method of template generation, matching, comparing and visualization applied to motion capture (kinematic) analysis. To evaluate our approach, we have used motion capture recordings (MoCap) of two highly-skilled black belt karate athletes consisting of 560 recordings of various karate techniques acquired with wearable sensors. We have evaluated the quality of generated templates; we have validated the matching algorithm that calculates similarities and differences between various MoCap data; and we have examined visualizations of important differences and similarities between MoCap data. We have concluded that our algorithms works the best when we are dealing with relatively short (2–4 s) actions that might be averaged and aligned with the dynamic time warping framework. In practice, the methodology is designed to optimize the performance of some full body techniques performed in various sport disciplines, for example combat sports and martial arts. We can also use this approach to generate templates or to compare the correct performance of techniques between various top sportsmen in order to generate a knowledge base of reference MoCap videos. The motion template generated by our method can be used for action recognition purposes. We have used the DTW classifier with angle-based features to classify various karate kicks. We have performed leave-one-out action recognition for the Shorin-ryu and Oyama karate master separately. In this case, 100% actions were correctly classified. In another experiment, we used templates generated from Oyama master recordings to classify Shorin-ryu master recordings and vice versa. In this experiment, the overall recognition rate was 94.2%, which is a very good result for this type of complex action.

Fatigue-related changes in technique emerge at different timescales during repetitive training

Training consisting of numerous repetitions performed as closely as possible to ideal techniques is common in sports and every-day tasks. Little is known about fatigue-related technique changes that emerge at different timescales when repeating complex actions such as a karate front kick. Accordingly, 15 karatekas performed 600 kicks (1 pre-block and 9 blocks). The pre-block comprised 6 kicks (3 with each leg) at maximum intensity (K-100%). Each block comprised 60 kicks (10 with each leg) at 80% of their self-perceived maximum intensity (K-80%) plus 6 K-100%. In between blocks, the participants rested for 90 seconds. Right leg kinematics (peak joint angles, peak joint angular velocities, peak joint linear resultant velocities, and time of occurrence of peaks) and kick duration corresponding to the K-80% were measured resulting in numerous variations with fatigue. At the timescale of tens of seconds, the changes involved variables that were related to velocity of execution (slowed down), while variables related to movement form were hardly affected. At the timescale of tens of minutes, the opposite results were observed. These findings challenge the long-standing rationale underlying repetitive training, suggesting instead that such involuntary variations in technique might play a crucial role in motor skill training.