Agonist and antagonist muscle activation in elite athletes: influence of age

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.

Child-Adult differences in antagonist muscle coactivation: A systematic review

Antagonist coactivation is the simultaneous activation of agonist and antagonist muscles during a motor task. Age-related changes in coactivation may contribute to observed differences in muscle performance between children and adults. Our aim was to systematically summarize age-related differences in antagonist muscle coactivation during multi-joint dynamic and single-joint isometric and isokinetic contractions. Electronic databases were searched for peer-reviewed studies comparing coactivation in upper or lower extremity muscles between healthy children and adolescents/young adults. Of the 1083 studies initially identified, 25 met eligibility criteria. Thirteen studies examined multi-joint dynamic movements, 10 single-joint isometric contractions, and 2 single-joint isokinetic contractions. Of the studies investigating multi-joint dynamic contractions, 83% (11/13 studies) reported at least one significant age-related difference: In 84% (9/11 studies) coactivation was higher in children, whereas 16% (2/11 studies) reported higher coactivation in adults. Among single-joint contractions, only 25% (3/12 studies) reported significantly higher coactivation in children. Fifty six percent of studies examined females, with no clear sex-related differences. Child-adult differences in coactivation appear to be more prevalent during multi-joint dynamic contractions, where generally, coactivation is higher in children. When examining child-adult differences in muscle function, it is important to consider potential age-related differences in coactivation, specifically during multi-joint dynamic contractions.

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.

Lower extremity isokinetic strength characteristics of amateur boxers

Aim: Sufficient strength and dynamic stability of the lower limbs are essential for improving punching force and preventing injury in amateur boxers. However, there are still no comprehensive reports on the isokinetic knee strength of boxers with different performance levels. The current study aimed to profile the isokinetic muscle strength of flexion and extension of the knee in boxers, as well as bilateral, unilateral, and functional ratios, and investigate the variation in these muscle strength characteristics associated with different performance levels.

Methods: Boxers were divided in two performance groups, elite (five males and four females) and non-elite groups (five males and four females). Muscle strength of the knee was determined via an IsoMed2000 device. Parameters examined included peak torque of the hamstring (H) and quadriceps (Q) during concentric (con) and eccentric (ecc) contractions at low (60°/S), medium (180°/S), and high (240°/S) speed and bilateral ratios (BLs), unilateral ratios (ULs), and functional ratios of dominant (D) and non-dominant limbs.

Results: In all angular velocities, the peak torque of H and Q was stronger in the elite group than in the non-elite group. ULs were lower in the elite group than in the non-elite group in Hcon/Qcon at 180D (p < 0.01) and 180ND (p < 0.05) and in Hecc/Qecc at 60D, 180D (p < 0.05) and 240D (p < 0.01). The elite group had higher BLs than the non-elite group in Hcon at 60°/S (p < 0.05) and Qcon at 180°/S (p < 0.05). The non-elite group had a higher functional ratio than elite boxers in Hecc/Qcon at 180D and 240D (p < 0.01).

Conclusion: Elite boxers had stronger knee strength in con and ecc contractions. All boxers had normal Hecc/Qecc and Hcon/Qecc. Hcon/Qcon and Hecc/Qcon were abnormal at lower angular velocity. Elite boxers had higher BLs and lower ULs, indicating that they are at a higher risk of injury.

Movement Patterns of Polish National Paralympic Team Wheelchair Fencers with Regard to Muscle Activity and Co-Activation Time

The aim of this study was to determine muscle co-activation and muscle activity time using EMG in Paralympic wheelchair fencers categorized into two disability-level groups: A (n= 7) and B (n= 9). The study was carried out with the use of a 16-channel EMG system. The surface EMG electrodes were placed on the fencer’s body along nine channels: arm muscles - deltoideus middle head (DEL), triceps brachii (TRI) and biceps brachii (BC); forearm muscles - extensor carpi radialis longus (ECR), flexor carpi radialis (FCR); postural (abdominal and back) muscles - the right and the left external oblique abdominal (EOA RT and LT) and latissimus dorsi (LD RT and LT). To assess the relative level of co-activation (simultaneous contraction of both muscles) for the TRI-BC, ECR-FCR, LD RT-EDA RT and LD LT-EDA LT muscle pairs, the co-activation index (CI) was calculated. The collected data were processed using Jamovi. The study hypotheses were verified at the level of significance of p≤0.05 (Welch’s t-test). The normal distribution of analyzed statistical features was checked with the Shapiro-Wilk test. The analysis of muscle activation time, as a percent ratio of three attempts executed in a series, confirmed the study assumptions. Fencers from Group A had a shorter activation time in all tested muscles, with the exception of the ECR (58.24), than fencers from Group B. This confirms that the activation of antagonist muscles representing a centrally programmed anticipatory mechanism stabilizing technical actions was particularly intensified in Group A fencers. The study results indicate that the standard co-activation index (CI) of key muscles involved in wheelchair fencing ranges from 48 to 51%.

Motor Competence in Individuals with Down Syndrome: Is an Improvement Still Possible in Adulthood?

In children, motor competence (MC) and the amount of physical activity are tightly interconnected. In adults with Down syndrome (DS), MC has been poorly addressed, resulting in a limited understanding of the possibility to improve MC over time. Here, we aim to: (1) investigate MC in adults with DS by comparing them with a group of typically developed peers and (2) verify the effect of an adapted karate program on MC. Adults with DS (DSG; n = 57) and typically developed adults (TDG; n = 21) performed the Test of Gross Motor Development version 3 (TGMD-3). The total TGMD-3 score (^TOTTGMD-3), the locomotor (^LOCTGMD-3), and object control (^OBJTGMD-3) scores were computed. After a 40 week adapted karate program, DSG (n = 37) underwent the post-training TGMD-3 assessment. Compared to TDG, DSG showed lower ^TOTTGMD-3 (DSG: 45.5 ± 17.3; TDG: 77.3 ± 9.5), ^LOCTGMD-3 (DSG: 22.2 ± 10.0; TDG: 36.2 ± 7.6) and ^OBJTGMD-3 (DSG: 23.3 ± 10.9; TDG: 41.1 ± 5.6). After the training, ^TOTTGMD-3, ^LOCTGMD-3 and ^OBJTGMD-3 increased by 35.6%, 30.0% and 40.7%, respectively. Our results suggest that MC acquisition does not evolve into a mature form in adulthood in individuals with DS. Moreover, a brief exposure to an adapted karate program induces an increase in motor competence in DS, even in adulthood.

Effects of Power and Ballistic Training on Table Tennis Players' Electromyography Changes

The aim of the present study was to analyze the effects of ballistic and power training on table tennis players' electromyography (EMG) changes. Thirty male table tennis players, who were able to perform top spin strikes properly, were randomly assigned to three groups: power training (PT; n = 10); ballistic training (BT; n = 10); and no training (CON = control group; n = 10). PT and BT were performed 3 times weekly for 8 weeks. Before and after training programs, a one-repetition maximum test (1RM) and the EMG activity of all the subjects' upper/lower body muscles while performing top spin strokes were analyzed. After training, significant interactions (group × time) were observed in increasing 1RM strength in upper/lower muscles (p < 0.05). However, neither training type had any significant effect on muscle EMG activity. These findings suggest that there should not necessarily be any significant change in the EMG signal after BT and PT despite the increase in muscle strength.

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.

Higher torque and muscle fibre conduction velocity of the Biceps Brachii in karate practitioners during isokinetic contractions

PURPOSE

Although upper limb techniques are largely utilized during karate combat competitions scarce information regarding their NM control is available. This study aims at investigating the effect of karate practice on the NM control of Biceps and Triceps Brachii during isokinetic contractions to enhance current knowledge on neuromuscular control adaptations and training methodologies in combat sports.

METHODS

Torque and surface electromyograms (sEMG) of Biceps Brachii Caput Longum (BB) and Triceps Brachii Lateral Head (TB) were recorded in eight karate practitioners (KA) and eight age-matched sedentary individuals (CO) during isokinetic elbow flexion-extensions (0-240°/s^-1). BB and TB sEMG amplitude (Root Mean Square - RMS) and frequency (Median Frequency - MDF) were computed during agonist and antagonist activity. Moreover, muscle fibre conduction velocity (MFCV) of the BB was computed.

RESULTS

During the isokinetic contractions, KA group demonstrated higher peak torque and higher MFCV in the BB with respect to CO. KA and CO presented comparable activation of agonist and antagonist muscles and comparable frequency content in both BB and TB.

CONCLUSIONS

The greater torque observed in KA should be interpreted in the light of a different motor unit recruitment strategy as suggested by the higher MFCV. Karate and combat sport practitioners should consider including in their training programmes methodologies emphasising neural rather than morphological adaptations.

Biochemical status, oxidative and antioxidant responses after 3-month specific training in elite karate athletes

Aim To investigate the effects of 3-month-long specific training program on biochemical status, oxidative and antioxidant responses in elite karatekas. Methods Twenty male karatekas [BMI: 21.9 ± 2.4 (kg/m²)] participated in this study. They performed a 3-month specific training to prepare for an international competition. We measured selected biochemical parameters, the oxidative and antioxidant responses before (T0) and after 3 months of intense karate training (T1). Results We found significant increases in catalase activity (26.3% ± 21.3%, p < 0.0005), superoxide dismutase activity (15.9% ± 28.8%, p < 0.05), and a significant decrease in malondialdehyde levels (17.2% ± 13.7%, p < 0.0005) after 3 months of karate training. Moreover, the athletes' biochemical status was significantly improved at T1 compared with T0 (for the majority of parameters, p < 0.0005). Conclusions The specific training program improves the prooxidant-antioxidant balance of elite karate athletes. It could be recommended for athletes having similar physical fitness level.

On the skilled plantar flexor motor action and unique electromyographic activity of ballet dancers

The study aimed to compare the ability of dance and non-dance subjects to perform fine control of a simple heel-raising/lowering movement, and to determine if there are any differences in motor unit activity in the primary plantar flexor muscles during the movement. Subjects were instructed to accurately track a sinusoidal trace with a heel-raising and lowering movement at four controlled frequencies (1, 0.5, 0.25, and 0.125 Hz). The ankle joint angle was used to characterize movement errors from the target. Surface electromyography was recorded from the soleus and medial gastrocnemius muscles. One trial including five sinusoidal traces was divided into two phases: an up phase and a down phase. To characterize motor unit activity of the plantar flexor muscles, a wavelet transform was applied to electromyographic signals recorded in each phase. For both phases, errors in movement accuracy were lower in dancers than in controls (8.7 ± 4.6 vs. 11.5 ± 6.8%, P < 0.05) regardless of the frequency of the sinusoidal wave traced. During the down phase, peak power of soleus electromyographic signals at ~ 10 Hz was statistically larger in control subjects than in dancers (10.4 ± 0.7 vs. 6.3 ± 0.4% total power, P < 0.05). These results indicate that dancers have a higher degree of motor skill in a heel raise tracking task and exhibit adaptations in the motor unit activity during skilled dynamic movements.

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

With the aim of comparing kinematic and neuromuscular parameters of Bandal Chagui kicks between 7 elite and 7 subelite taekwondo athletes, nine Bandal Chaguis were performed at maximal effort in a selective reaction time design, simulating the frequency of kicks observed in taekwondo competitions. Linear and angular leg velocities were recorded through 3D motion capture system. Ground reaction forces (GRF) were evaluated by a force platform, and surface electromyographic (sEMG) signals were evaluated in the vastus lateralis, biceps femoris, rectus femoris, tensor fasciae lata, adductor magnus, gluteus maximus, gluteus medius, and gastrocnemius lateralis muscles of the kicking leg. sEMG data were processed to obtain the cocontraction indices (CI) of antagonist vs. overall (agonist and antagonist) muscle activity. CI was measured for the hip and knee, in flexion and extension, and for hip abduction. Premotor, reaction (kinetic and kinematic), and kicking times were evaluated. Timing parameters, except kinetic reaction time, were faster in elite athletes. Furthermore, CI and angular velocity during knee extension, foot and knee linear velocity, and horizontal GRF were significantly higher in elite than in subelite athletes. In conclusion, selected biomechanical parameters of Bandal Chagui appear to be useful in controlling the training status of the kick and in orienting the training goal of black belt competitors.