The effect of match fatigue in elite badminton players using plantar pressure measurements and the implications to injury mechanisms

Robust fatigue markers obtained from muscle synergy analysis

This study aimed to utilize the nonnegative matrix factorization (NNMF) algorithm for muscle synergy analysis, extracting synergy structures and muscle weightings and mining biomarkers reflecting changes in muscle fatigue from these synergy structures. A leg press exercise to induce fatigue was performed by 11 participants. Surface electromyography (sEMG) data from seven muscles, electrocardiography (ECG) data, Borg CR-10 scale scores, and the z-axis acceleration of the weight block were simultaneously collected. Three indices were derived from the synergy structures: activation phase difference, coactivation area, and coactivation time. The indicators were further validated for single-leg landing. Differences in heart rate (HR) and heart rate variability (HRV) were observed across different fatigue levels, with varying degrees of disparity. The median frequency (MDF) exhibited a consistent decline in the primary working muscle groups. Significant differences were noted in activation phase difference, coactivation area, and coactivation time before and after fatigue onset. Moreover, a significant correlation was found between the activation phase difference and the coactivation area with fatigue intensity. The further application of single-leg landing demonstrated the effectiveness of the coactivation area. These indices can serve as biomarkers reflecting simultaneous alterations in the central nervous system and muscle activity post-exertion.

Does lower extremity stiffness influence change of direction speed in badminton athletes after dynamic loaded warm-up?

This study investigated whether lower extremity stiffness plays a role in the enhancement of change of direction speed (CODS) and the duration of this enhancement after dynamic loaded warm-up (DLWU). Fifteen badminton athletes underwent DLWU, and CODS, individual muscle and tendon stiffness, and vertical stiffness were measured before DLWU and 6, 12, and 18 min after DLWU. The data were analyzed using ANOVA and covariance analysis. Significant improvements in CODS were found at 6, 12, and 18 min post-DLWU compared to pre-DLWU (p < 0.05). The Achilles tendon stiffness of the dominant leg increased at 6 min (p = 0.039) and 18 min (p = 0.024) post-DLWU compared to pre-DLWU. Achilles tendon stiffness of the dominant leg had a significant effect on improving CODS (p > 0.05). CODS improvement lasted up to 18 min after DLWU in badminton athletes, potentially related to increased Achilles tendon stiffness of the dominant leg.

Impact of specialized fatigue and backhand smash on the ankle biomechanics of female badminton players

During fatigued conditions, badminton players may experience adverse effects on their ankle joints during smash landings. In addition, the risk of ankle injury may vary with different landing strategies. This study aimed to investigate the influence of sport-specific fatigue factors and two backhand smash actions on ankle biomechanical indices. Thirteen female badminton players (age: 21.2 ± 1.9 years; height: 167.1 ± 4.1 cm; weight: 57.3 ± 5.1 kg; BMI: 20.54 ± 1.57 kg/m2) participated in this study. An 8-camera Vicon motion capture system and three Kistler force platforms were used to collect kinematic and kinetic data before and after fatigue for backhand rear-court jump smash (BRJS) and backhand lateral jump smash (BLJS). A 2 × 2 repeated measures analysis of variance was employed to analyze the effects of these smash landing actions and fatigue factors on ankle biomechanical parameters. Fatigue significantly affected the ankle-joint plantarflexion and inversion angles at the initial contact (IC) phase (p < 0.05), with both angles increasing substantially post-fatigue. From a kinetic perspective, fatigue considerably influenced the peak plantarflexion and peak inversion moments at the ankle joint, which resulted in a decrease the former and an increase in the latter after fatigue. The two smash landing actions demonstrated different landing strategies, and significant main effects were observed on the ankle plantarflexion angle, inversion angle, peak dorsiflexion/plantarflexion moment, peak inversion/eversion moment, and peak internal rotation moment (p < 0.05). The BLJS landing had a much greater landing inversion angle, peak inversion moment, and peak internal rotation moment compared with BRJS landing. The interaction effects of fatigue and smash actions significantly affected the muscle force of the peroneus longus (PL), with a more pronounced decrease in the force of the PL muscle post-fatigue in the BLJS action(post-hoc < 0.05). This study demonstrated that fatigue and smash actions, specifically BRJS and BLJS, significantly affect ankle biomechanical parameters. After fatigue, both actions showed a notable increase in IC plantarflexion and inversion angles and peak inversion moments, which may elevate the risk of lateral ankle sprains. Compared with BRJS, BLJS poses a higher risk of lateral ankle sprains after fatigue.

Comparison of mechanical energy transfer during right-forward lunge between female amateur and professional badminton players

BACKGROUND

Regarding their skill levels, badminton players present different movement patterns during front and right lunging. The main objective of this study was to compare the mechanical energy transfers attributable to right-forward lunges between amateur and professional badminton players to study variations in mechanical efficiency at various skill levels.

METHOD

In this cross-sectional study, twenty female badminton players were recruited (Professional group n = 10 and Amateur group n = 10). The kinematics and kinetics of the lower extremities were recorded while performing right-forward lunges using Vicon motion capture and Kistler force plates. Mechanical energy expenditures (MEE) were extracted in eccentric transfer, concentric transfer, and no-transfer phases for the hip, knee, and ankle joints. At each joint, mechanical energy compensations (MEC) were also determined. Independent samples t-tests were used to analyze data at a significance level of α = 0.05.

RESULT

Regards to mechanical energy expenditures at the initial heel contact phase, the professional players demonstrated statistically significant more ankle no-transfer (p < 0.003), less knee concentric transfer (p < 0.026), more knee eccentric transfer (p < 0.001), and less hip no-transfer (p < 0.001). At the same time, the amateur athletes showed significantly more ankle eccentric transfer (p < 0.042) at maximal knee flexion angle time point. Analyzing mechanical energy compensation coefficients showed that the professional athletes had significantly less ankle concentric transfer (p < 0.001), more knee concentric transfer (p < 0.001), more knee eccentric transfer (p < 0.001), and more hip eccentric transfer (p < 0.001) at initial contact phase. While they found to have significantly more ankle eccentric transfer (p < 0.007), less knee concentric transfer (p < 0.001), less knee eccentric transfer (p < 0.001), more hip concentric transfer (p < 0.001), and more hip eccentric transfer (p < 0.001) at maximal knee flexion angle.

CONCLUSION

it is shown that the mechanical energy efficiency of the right-forward lunge is skill-related. It seems that altered lunge landing biomechanics may increase the risk of ankle and knee injuries and muscular damages in amateur athletes. It is recommended for amateur players to follow a injury prevention training program that promotes proper lunging technique.

Dose-response effect of incremental lateral-wedge hardness on the lower limb Biomechanics during typical badminton footwork

Badminton footwork has been characterised with jump-landing, cross step, side side and lunges, which requires movement agility to facilitate on-court performance. A novel badminton shoe design with systematic increase of lateral wedge hardness (Asker C value of 55, 60, 65, and 70) was developed and investigated in this study, aiming to analyse the dose-response effect of incremental wedge hardness on typical badminton footwork. Stance time and joint stiffness were employed to investigate the footwork performance, and the factorial Statistical non-Parametric Mapping and Principal Component Analysis (PCA) were used to quantify the biomechanical responses over the stance. As reported, shorter contact times (decreased by 8.9%-13.5%) and increased joint stiffness (in side step) of foot-ankle complex were found, suggesting improved footwork stability and agility from increased hardness. Time-varying differences were noted during the initial landing and driving-off phase of cross and side steps and drive-off returning of lunges, suggesting facilitated footwork performance. The reconstructed modes of variations from PCA further deciphered the biomechanical response to the wedge dosage, especially during drive-off, to understand the improved footwork agility and stability.

The effects of ankle dorsiflexor fatigue on lower limb biomechanics during badminton forward forehand and backhand lunge

Background: Local muscle fatigue may have an adverse effect on the biomechanics of the lunge movement and athletic performance. This study analyzed the biomechanical indicators of the forward lunge in badminton players before and after fatigue of the ankle dorsiflexors. Methods: Using the isometric muscular strength testing system, 15 badminton players underwent an ankle dorsiflexor fatigue test. Before and after the fatigue experiment, five lunges were done in both the forehand forward (FH) and backhand forward (BH) directions, five in each direction. A Vicon motion capture system and an AMTI force measuring station were used to record lower limb kinematic and ground reaction force (GRF). Pre-fatigue and post-fatigue variability were determined using paired-samples t-tests, Wilcoxon signed rank test, and Statistical Non-parametric Mapping (SNPM). Result: The results showed that after fatigue, the peak angle of ankle dorsiflexion was significantly reduced (p = 0.034), the range of motion (ROM) of the ankle sagittal plane (p = 0.000) and peak angle of ankle plantarflexion (p = 0.001) was significantly increased after forehand landing. After fatigue, ankle inversion was significantly increased after forehand and backhand landings (FH: p = 0.033; BH: p = 0.015). After fatigue, peak knee flexion angles increased significantly (FH: Max: p = 0.000, Min: p = 0.000; BH: Max: p = 0.017, Min: p = 0.037) during forehand and backhand landings and ROM in knee flexion and extension increased (p = 0.009) during forehand landings. Knee inversion range of motion was significantly increased after fatigue (p = 0.024) during forehand landings. Peak hip flexion angle (p = 0.000) and range of motion (p = 0.000) were significantly reduced in forehand landings after fatigue. The mean loading rate (p = 0.005) and the maximum loading rate (p = 0.001) increased significantly during backhand landings after fatigue. Post-fatigue, the center of pressure (COP) frontal offset increased significantly (FH: p = 0.000; BH: p = 0.000) in the forehand and backhand landings. Conclusion: These results indicate that when the ankle dorsiflexors are fatigued, the performance of the forehand is significantly negatively affected, and the impact force of the backhand is greater.

Vision-based movement recognition reveals badminton player footwork using deep learning and binocular positioning

Coordinating dynamic interceptive actions in sports like badminton requires skilled performance in getting the racket into the right place at the right time. For this reason, the strategic movement and placement of one's feet, or footwork, is an important part of competitive performance. Developing an automated, efficient, and economical method to record individual movement characteristics of players is critical and can benefit athletes and motor control specialists. Here, we propose new methods for recording data on the footwork of individual badminton players, in which deep learning is used to obtain image coordinates (2D) of their shoes and binocular positioning to reconstruct the 3D coordinates of the shoes. Results show that the final positioning accuracy is 74.7%. Using the proposed methods, we revealed inter-individual adaptations in the footwork of several participants during competitive performance. The data provided insights on how individual participants coordinated footwork to intercept the projectile, by varying the distance traveled on court and jump height. Compared with visual observations by biomechanists and motor control specialists, the proposed methods can obtain quantitative data, provide analysis and evaluation of each participant's performance, revealing personal characteristics that could be targeted to shape the individualized training programs of players to refine their badminton footwork.

Smart Insole Based on Flexi Force and Flex Sensor for Monitoring Different Body Postures

This study aims to fabricate smart insoles using wireless Flexi force and bend sensing technology. Polyvinyl chloride (PVC) film was chosen as the substrate to hold all the sensors. The developed smart insole has a three-layer structure (insole-PVC layer-fabric layer) and is calibrated in an isolation laboratory to evaluate its measurement performance. One male volunteer subject exhibited four different body postures, namely tree pose, forward-leaning, squatting, and forward folding pose. Changes in pressure distribution were considered to be similar for the forward, squat, and forward-folded positions. When subjects performed a full squat, the flex sensor exhibited maximum flexion during the squat position, and the flex sensor response against the squat pose was found to be higher by about 18.18% than in the forward lean, respectively. The tree pose has the highest error rate at the first metatarsal, about 18.6%, of which the maximum absolute relative error of the sensor is less than 5%. Plantar pressure distribution and body posture measurements were successfully validated using Flexi force and flex sensors embedded in the smart insole. The smart insole proposed in this research work has broader prospects for clinical application.

Effects of badminton insole design on stress distribution, displacement and bone rotation of ankle joint during single-leg landing: a finite element analysis

Previous research has reported that up to 92% of injuries amongst badminton players consist of lower limb, whereby 35% of foot fractures occurred at the metatarsal bone. In sports, insoles are widely used to increase athletes' performance and prevent many injuries. However, there is still a lack of badminton insole analysis and improvements. Therefore, this study aimed to biomechanically analyse three different insole designs. A validated and converged three-dimensional (3D) finite element model of ankle-foot complex was developed, which consisted of the skin, talus, calcaneus, navicular, three cuneiform, cuboid, five metatarsals and five phalanges. Three existing insoles from the market, (1) Yonex Active Pro Truactive, (2) Victor VT-XD 8 and (3) Li-Ning L6200LA, were scanned using a 3D scanner. For the analysis, single-leg landing was simulated. On the superior surface of the skin, 2.57 times of the bodyweight was axially applied, and the inferior surface of the outsole was fixed. The results showed that Insole 3 was the most optimum design to reduce peak stress on the metatarsals (3.807 MPa). In conclusion, the optimum design of Insole 3, based on the finite element analysis, could be a justification of athletes' choices to prevent injury and other complications.

Activity recognition using multiplex limited penetrable visibility graph

To solve the dynamic problem of different activities in human activity recognition research, an activity recognition method based on a multiplex limited penetrable visibility graph is proposed. The 21 pressure values for each sampling are mapped to nodes in the first-layer network; then the average path length of nodes in the asynchronous periodic network is obtained, and the second-layer network used to explore different activities is built. Finally, the characteristic parameters and dynamic characteristics of different activities are explored and analyzed. The experimental results demonstrate that through the joint distribution of the average clustering coefficient and the maximum degree parameter of the node, the discrimination problems of different postures can be better realized, and it has good adaptability. It provides a new approach to gait recognition research that can be used in medical clinical diagnosis, rehabilitation training, and public health.

Plantar Pressure Variability and Asymmetry in Elderly Performing 60-Minute Treadmill Brisk-Walking: Paving the Way towards Fatigue-Induced Instability Assessment Using Wearable In-Shoe Pressure Sensors

Evaluation of potential fatigue for the elderly could minimize their risk of injury and thus encourage them to do more physical exercises. Fatigue-related gait instability was often assessed by the changes of joint kinematics, whilst planar pressure variability and asymmetry parameters may complement and provide better estimation. We hypothesized that fatigue condition (induced by the treadmill brisk-walking task) would lead to instability and could be reflected by the variability and asymmetry of plantar pressure. Fifteen elderly adults participated in the 60-min brisk walking trial on a treadmill without a pause, which could ensure that the fatigue-inducing effect is continuous and participants will not recover halfway. The plantar pressure data were extracted at baseline, the 30th minute, and the 60th minute. The median of contact time, peak pressure, and pressure-time integrals in each plantar region was calculated, in addition to their asymmetry and variability. After 60 min of brisk walking, there were significant increases in peak pressure at the medial and lateral arch regions, and central metatarsal regions, in addition to their impulses (p < 0.05). In addition, the variability of plantar pressure at the medial arch was significantly increased (p < 0.05), but their asymmetry was decreased. On the other hand, the contact time was significantly increased at all plantar regions (p < 0.05). The weakened muscle control and shock absorption upon fatigue could be the reason for the increased peak pressure, impulse, and variability, while the improved symmetry and prolonged plantar contact time could be a compensatory mechanism to restore stability. The outcome of this study can facilitate the development of gait instability or fatigue assessment using wearable in-shoe pressure sensors.

Delayed peroneal muscle reaction time in male amateur footballers during a simulated prolonged football protocol

Peroneal muscle fatigue could result in ankle inversion sprain injuries. This study investigated the peroneal muscle reaction time during a simulated prolonged football protocol. Nine male footballers completed a 105-minute simulated prolonged football protocol. The peroneal muscle reaction time to an ankle inversion perturbation was measured every 15 minutes by a surface electromyography system sampling at 1000 Hz. One-way repeated ANOVA with post-hoc paired t-test showed a steady upward trend starting from 48.9 ms at baseline to 57.1 ms at the end of the first half, followed by a recovery back to 50.9 ms at the start of the second half and a further delay in the last 30 minutes to 60.2 ms at the end of the protocol. Delayed peroneal muscle reaction was found after 30 minutes of the first half and 15 minutes of the second half of a football match. The risk of ankle sprain could increase in the latter minutes in each half protocol. Thus, prevention injury training strategies should focus on these specific durations in football matches.

Biomechanics of lower limb in badminton lunge: a systematic scoping review

Background

Badminton is a popular sport activity in both recreational and elite levels. A lot of biomechanical studies have investigated badminton lunge, since good lunge performance may increase the chances to win the game. This review summarized the current trends, research methods, and parameters-of-interest concerning lower-extremity biomechanics in badminton lunges.

Methodology

Databases including Web of Science, Cochrane Library, Scopus, and PubMed were searched from the oldest available date to September 2020. Two independent authors screened all the articles and 20 articles were eligible for further review. The reviewed articles compared the differences among playing levels, footwear designs, and lunge directions/variations, using parameters including ground reaction forces, plantar pressure distribution, kinematics, and kinetics.

Results

Elite badminton players demonstrated higher impact attenuation capability, more aggressive knee and ankle strategy (higher mechanical moment), and higher medial plantar load than amateur players. Footwear modifications can influence comfort perception and movement mechanics, but it remains inconclusive regarding how these may link with lunging performance. Contradicting findings in kinematics is possibly due to the variations in lunge and instructions.

Conclusions

Playing levels and shoe designs have significant effects on biomechanics in badminton lunges. Future studies can consider to use an unanticipated testing protocol and realistic movement intensity. They can study the inter-limb coordination as well as the contributions and interactions of intrinsic and extrinsic factors to injury risk. Furthermore, current findings can stimulate further research studying whether some specific footwear materials with structural design could potentially compromise impact attenuation, proprioception, and performance.

Delayed ankle muscle reaction time in female amateur footballers after the first 15 min of a simulated prolonged football protocol

PURPOSE

Ankle sprain injury rate is reported to be higher towards the end of a football match. Muscle fatigue may contribute to the delayed muscle reaction and subsequent injury. This study investigated the ankle muscle reaction time during a simulated, prolonged football protocol.

METHODS

Seven amateur female football players participated in a 105-min simulated, prolonged football protocol. An ankle muscle reaction test was conducted with a pair of ankle sprain simulators at a scheduled interval every 15-min. The reaction times of peroneus longus, tibialis anterior, and lateral gastrocnemius were collected using an electromyography system sampling at 1000 Hz. Repeated measures one-way multivariate analysis of variance with post-hoc paired t-tests were conducted to evaluate if the reaction time at each time point significantly differed from baseline. Statistical significance was set at p < 0.05 level.

RESULTS

Reaction times started from 40.5-47.7 ms at baseline and increased to 48.6-55.7 ms at the end. Reaction times significantly increased in all muscles after the first 15 min except for the dominant lateral gastrocnemius. Increased reaction times were seen in the non-dominant limb after 60 min for tibialis anterior, after 75 min for peroneus longus, and after 90 min for the lateral gastrocnemius.

CONCLUSIONS

Delayed reaction time of the ankle muscles were found after the first 15 min and in the final 45 min of a simulated prolonged football protocol. Strategies for injury prevention should also focus on tackling the delayed ankle muscle reaction time in the acute phase (the first 15 min), in addition to the latter minutes in the second half.

LEVEL OF EVIDENCE

Controlled laboratory study, Level V.