Hexagonal Barbell Deadlift One-repetition Maximum Estimation Using Velocity Recordings.

This study aimed to determine whether the optimal minimal velocity threshold (MVT) provides more precise estimates of one-repetition maximum (1RM) in the hexagonal barbell deadlift (HBD) than the general and individual MVTs. The 1RMs of 27 resistance-trained males were predicted using three types of MVT: (i) General MVT: averaged across subjects' velocity of the 1RM trial (0.25 m·s-1), (ii) individual MVT: velocity attained during the 1RM trial, and (iii) Optimal MVT: MVT that eliminated the differences between the actual and predicted 1RM. Two individual load-velocity relationships were modelled considering five (30-50-70-80%1RM) or six (30-50-70-80-90%1RM) loading conditions. Negligible differences (Effect size<0.20), low absolute errors (<5% of the actual 1RM), and extremely high correlations (r>0.90) were observed between the actual and six predicted 1RMs. The only significant difference was the lower raw errors for the 90%1RM condition (0.60±7.34 kg) compared to the 80%1RM condition (2.27±7.54 kg; p=0.013). These results suggest that the individual load-velocity relationship offers an accurate estimation of the HBD 1RM in resistance-trained males, and these estimates could maintain similar levels of precision across different types of MVT (general, individual, and optimal) and final tested loads (80%1RM and 90%1RM).

Biomechanical Investigation of Lower Limbs during Slope Transformation Running with Different Longitudinal Bending Stiffness Shoes.

BACKGROUND: During city running or marathon races, shifts in level ground and up-and-down slopes are regularly encountered, resulting in changes in lower limb biomechanics. The longitudinal bending stiffness of the running shoe affects the running performance. PURPOSE: This research aimed to investigate the biomechanical changes in the lower limbs when transitioning from level ground to an uphill slope under different longitudinal bending stiffness (LBS) levels in running shoes. METHODS: Fifteen male amateur runners were recruited and tested while wearing three different LBS running shoes. The participants were asked to pass the force platform with their right foot at a speed of 3.3 m/s ± 0.2. Kinematics data and GRFs were collected synchronously. Each participant completed and recorded ten successful experiments per pair of shoes. RESULTS: The range of motion in the sagittal of the knee joint was reduced with the increase in the longitudinal bending stiffness. Positive work was increased in the sagittal plane of the ankle joint and reduced in the keen joint. The negative work of the knee joint increased in the sagittal plane. The positive work of the metatarsophalangeal joint in the sagittal plane increased. CONCLUSION: Transitioning from running on a level surface to running uphill, while wearing running shoes with high LBS, could lead to improved efficiency in lower limb function. However, the higher LBS of running shoes increases the energy absorption of the knee joint, potentially increasing the risk of knee injuries. Thus, amateurs should choose running shoes with optimal stiffness when running.

Influence of Torsional Stiffness in Badminton Footwear on Lower Limb Biomechanics.

Torsional stiffness of athletic footwear plays a crucial role in preventing injury and improving sports performance. Yet, there is a lack of research focused on the biomechanical effect of torsional stiffness in badminton shoes. This study aimed to comprehensively investigate the influence of three different levels of torsional stiffness in badminton shoes on biomechanical characteristics, sports performance, and injury risk in badminton players. Fifteen male players, aged 22.8 ± 1.96 years, participated in the study, performing badminton-specific tasks, including forehand clear stroke [left foot (FCL) and right foot (FCR)], 45-degree sidestep cutting (45C), and consecutive vertical jumps (CVJ). The tasks were conducted wearing badminton shoes of torsional stiffness measured with Shore D hardness 50, 60, and 70 (referred to as 50D, 60D, and 70D, respectively). The primary biomechanical parameters included ankle, knee, and MTP joint kinematics, ankle and knee joint moments, peak ground reaction forces, joint range of motion (ROM), and stance time. A one-way repeated measures ANOVA was employed for normally distributed data and Friedman tests for non-normally distributed data. The 70D shoe exhibited the highest ankle dorsiflexion and lowest ankle inversion peak angles during 45C task. The 60D shoe showed significantly lower knee abduction angle and coronal motions compared to the 50D and 70D shoes. Increased torsional stiffness reduced stance time in the FCR task. No significant differences were observed in anterior-posterior and medial-lateral ground reaction forces (GRF). However, the 70D shoe demonstrated higher vertical GRF than the 50D shoe while performing the FCR task, particularly during 70% - 75% of stance. Findings from this study revealed the significant role of torsional stiffness in reducing injury risk and optimizing performance during badminton tasks, indicating that shoes with an intermediate level of stiffness (60D) could provide a beneficial balance between flexibility and stability. These findings may provide practical references in guiding future badminton shoe research and development. Further research is necessary to explore the long-term effects of altering stiffness, considering factors such as athletic levels and foot morphology, to understand of the influence of torsional stiffness on motion biomechanics and injury prevalence in badminton-specific tasks.

Applications of Finite Element Modeling in Biomechanical Analysis of Foot Arch Deformation: A Scoping Review.

Excessive foot arch deformation is associated with plantar tissue overload and ligamentous injury pathologies. Finite element (FE) analysis, as an effective tool for modeling and simulation, has been utilized clinically for providing insights into arch biomechanics. This systematic scoping review aimed to summarize the current state of computational modeling techniques utilized in arch biomechanics from 2000 onwards and outline the main challenges confronting the further development of accurate models in clinical conditions. English-language searches of the electronic databases were conducted in the Web of Science, PubMed, and Scopus until July 2022. Articles that investigated arch deformation mechanisms by FE modeling were included. The methodological quality was assessed utilizing the Methodological Quality Assessment of Subject-Specific Finite Element Analysis Used in Computational Orthopedics (MQSSFE). Seventeen articles were identified in this systematic scoping review, mostly focusing on constructing models for specific pathological conditions, such as progressive collapsing foot deformity, valgus foot, and posterior tibial tendon dysfunction. However, given the complexity of the arch problem, geometrical simplifications regarding the balance between accurate detail and computational cost and assumptions made in defining modeling parameters (material properties and loading and boundary conditions) may bring challenges to the accuracy and generalizability of models applied to clinical settings. Overall, advances in computational modeling techniques have contributed to reliable foot deformation simulation and analysis in modern personalized medicine.

A Systematic Review and Meta-Analysis Investigating Head Trauma in Boxing.

OBJECTIVES: Although physical trauma has been reported in boxing since its inception, boxing still appeals to athletes and spectators. This systematic review and meta-analysis assess both acute and chronic neurological and neuropsychological effects that boxing has on the brain. Further assessments in terms of comparisons of the concussion ratio in boxing to other combat sports, as well as the efficiency of wearing headguards, are also performed. DATA SOURCES: This systematic review and meta-analysis used the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. The outcomes incorporated included physical chronic abnormalities of the brain, neuropsychiatric, and neurological disorders sustained in amateur or professional boxing, in addition to the safety benefits of boxing headguards. Odds ratios, descriptive statistics, and inferential statistics are also reported. MAIN RESULTS: From the 84 articles reviewed, the 35 included articles suggested that boxers have a significantly elevated risk of sustaining a concussion compared with other combat sports (risk ratio [RR]: 0.253 vs RR: 0.065, P < 0.001). From the 631 amateur and professional boxers analyzed, 147 (23.30%) had cavum septum pellucidum, whereas 125 of 411 amateur and professional boxers (30.41%) presented with some form of brain atrophy. Dementia or amnesia was observed in 46 of 71 boxers (61.79%), 36 of 70 (51.43%) had various forms and severities of cognitive disorders, and 57 of 109 (52.29%) displayed abnormal computed tomography or electroencephalogram scan results. Utilization of headguards significantly increased the risk for stoppages in amateur bouts, compared with boxers not wearing a headguard (OR: 1.75 vs 0.53, P < 0.050). CONCLUSIONS: Boxing is a hazardous sport that has the potential to have fatal and negative life-changing results. Because of the limited reliable data regarding the efficiency of boxing headguards, future research should focus on the overall significance that headguards may have for reducing head trauma.

Influence of unilateral and bilateral knee extension fatigue protocols on inter-limb asymmetries assessed through countermovement jumps.

This study explores the sensitivity of jump type (unilateral and bilateral) and output variable (mean force, propulsive impulse, and jump height) to detect the changes in inter-limb asymmetries induced by unilateral and bilateral fatigue protocols. Thirty-eight individuals performed two testing sessions that consisted of (I) nine "pre-fatigued" countermovement jumps (CMJs; three bilateral and six unilateral [three with each leg]), (II) fatigue protocol and (III) nine "post-fatigued" CMJs. The testing sessions only differed in the fatigue protocol (five sets to failure against the 15-repetition maximum load using either the unilateral or bilateral knee extension exercise). The magnitude of all CMJ-derived variables (mean force, impulse, and jump height) decreased following both unilateral (p ≤ 0.002) and bilateral fatigue protocols (p ≤ 0.018). However, only unilateral protocol accentuated inter-limb asymmetries, which was detected for all variables during the unilateral CMJ (from -4.33% to -2.04%; all p < 0.05) but not during the bilateral CMJ (from -0.64% to 0.54%; all p > 0.05). The changes in inter-limb asymmetries following the unilateral and bilateral fatigue protocols were not significantly correlated between the unilateral and bilateral CMJs (rs ≤ 0.172). The unilateral CMJ should be recommended for the testing purposes over the bilateral CMJ due to its greater sensitivity to detect the selective effects of fatigue.

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.

An Acute Transition from Rearfoot to Forefoot Strike does not Induce Major Changes in Plantarflexor Muscles Activation for Habitual Rearfoot Strike Runners.

Footstrike pattern has received increased attention within the running community because there is a common belief that forefoot strike running (FFS) is more advantageous (i.e., improve performance and reduce running injuries) than rearfoot strike running (RFS) in distance running. Literature reports suggest greater knee joint flexion magnitude and initial knee angle during stance in FFS compared with RFS running We examined the EMG activation of the triceps surae muscles during an acute transition from RFS to FFS strike. We tested the hypothesis that due to larger knee flexion in FFS the gastrocnemius muscles possibly decrease their EMG activity because muscle fascicles operate under unfavorable conditions. Fourteen competitive healthy middle- and long-distance runners who were habitual RFS runners ran on a treadmill at three speeds: 12, 14, and 16 km·h-1. Each running speed was performed with both FFS and RFS patterns. Lower limb kinematics in the sagittal plane and normalized electromyography (EMG) activity of medial gastrocnemius proximal, middle and distal regions, lateral gastrocnemius and soleus muscles were compared between footstrike patterns and running speeds across the stride cycle. Contrary to our expectations, the knee joint range of motion was similar in FFS and RFS running. However, the sagittal plane ankle joint motion was greater (p < 0.01) while running with FFS, resulting in a significantly greater muscle-tendon unit lengthening (p < 0.01) in FFS compared with RFS running. In addition, medial and lateral gastrocnemius showed higher EMG activity in FFS compared with RFS running in the late swing and early stance but only for a small percentage of the stride cycle. However, strike patterns and running speed failed to induce region-specific activation differences within the medial gastrocnemius muscle. Overall, well-trained RFS runners are able to change to FFS running by altering only the ankle joint kinematics without remarkably changing the EMG activity pattern.

COVID-19 lockdown consequences on body mass index and perceived fragility related to physical activity: A worldwide cohort study.

BACKGROUND: This paper is a follow-up study continuing the COVISTRESS network previous research regarding health-related determinants. OBJECTIVE: The aim was to identify the main consequences of COVID-19 lockdown on Body Mass Index and Perceived Fragility, related to Physical Activity (PA), for different categories of populations, worldwide. DESIGN: The study design included an online survey, during the first wave of COVID-19 lockdown, across different world regions. SETTING AND PARTICIPANTS: The research was carried out on 10 121 participants from 67 countries. The recruitment of participants was achieved using snowball sampling techniques via social networks, with no exclusion criteria other than social media access. MAIN OUTCOME MEASURES: Body Mass Index, Physical Activity, Perceived Fragility and risk of getting infected items were analysed. SPSS software, v20, was used. Significance was set at P < .05. RESULTS: Body Mass Index significantly increased during lockdown. For youth and young adults (18-35 years), PA decreased by 31.25%, for adults (36-65 years) by 26.05% and for the elderly (over 65 years) by 30.27%. There was a high level of Perceived Fragility and risk of getting infected for female participants and the elderly. Correlations between BMI, Perceived Fragility and PA were identified. DISCUSSION AND CONCLUSIONS: The research results extend and confirm evidence that the elderly are more likely to be at risk, by experiencing weight gain, physical inactivity and enhanced Perceived Fragility. As a consequence, populations need to counteract the constraints imposed by the lockdown by being physically active.

Influence of metatarsophalangeal joint stiffness on take-off performances and lower-limb biomechanics in jump manoeuvres.

Forefoot and toes are prominent regions for locomotion and individual metatarsophalangeal joint (MTPJ) stiffness may be linked to jump take-off mechanics and performances. However, little is known about the relationships between MTPJ stiffness and take-off related variables. This study examined the relationship between individual MTPJ stiffness and biomechanical variables under various vertical countermovement jumps (CMJ) conditions. We measured MTPJ stiffness on 21 male university basketball players and then asked them to perform jumps under single, consecutive and running CMJ conditions. Pearson's correlation coefficient was employed to examine the relationships between MTP passive stiffness and each jumping performance, ground reaction force (GRF) and joint kinematic and kinetic variables. The results indicated that MTPJ stiffness significantly correlated with maximum jump height (r = 0.49, moderate), peak take-off velocity (r = 0.47, moderate), peak take-off ankle plantarflexion moment (r = 0.68, strong), peak dorsiflexion moment (r = 0.60, strong) and peak take-off ankle power (r = 0.44, moderate) in consecutive CMJ. Only a moderate correlation between MTPJ stiffness and peak MTPJ extension take-off velocity (r = -0.46, moderate) was determined in a single CMJ. There were no significant correlations found in running CMJ conditions. These findings imply that higher MTPJ stiffness of participants was related to improved jump performances in consecutive jumps.

The Use of Metallic Nanoparticles in Wound Healing: New Perspectives.

Chronic wounds represent a challenge for the health area, as they directly impact patients' quality of life and represent a threat to public health and the global economy due to their high cost of treatment. Alternative strategies must be developed for cost-effective and targeted treatment. In this scenario, the emerging field of nanobiotechnology may provide an alternative platform to develop new therapeutic agents for the chronic wound healing process. This manuscript aims to demonstrate that the application of metallic nanoparticles (gold, silver, copper, and zinc oxide) opened a new chapter in the treatment of wounds, as they have different properties such as drug delivery, antimicrobial activity, and healing acceleration. Furthermore, metallic nanoparticles (NPs) produced through green synthesis ensure less toxicity in biological tissues, and greater safety of applicability, other than adding the effects of NPs with those of extracts.

Do Arch Height and Arch Stiffness Relate to Physical Performance in Adult Men?

Foot arch plays an important role in bearing body weight, absorbing ground reaction forces and maintaining balance, and its structure and function are bound to have a profound effect on physical activities and sports. Arch height and arch stiffness are 2 factors that represent the structure and function of the arch. Therefore, the purpose of this study was to explore the associations of arch height and arch stiffness with physical performance. A total of 56 men (aged 49.00 ± 7.95 years, mean body mass index [BMI] 26.80 ± 3.75 kg/m2) participated in this study. A 3-dimensional laser scanner was employed to obtain foot structure information of each participant, from which the arch height index (AHI) and arch stiffness index (ASI) were computed. Physical performance measures including agility, power, and proprioception were tested in a random order. The results indicated that the stepping forward and backward and vertical jump that represent agility and force respectively were negatively and significantly associated with AHI (r = -0.27, p = .045; r = -0.35, p = .009). When adjusted for age and BMI, only height of vertical jump was found to be correlated significantly with AHI (r = -0.29, p = .040); while no significant relationships were observed between physical performance measures and ASI. Multivariate linear regression analysis showed that AHI, age, and BMI can effectively predict the height of vertical jump. This study demonstrates that there is a negative correlation between arch height and muscle power of lower limbs in adult men.

Age score for assessing motor function in Chinese community-dwelling older women.

The study aimed to develop a physical fitness age score to assess motor function in community-dwelling elderly women and verify its validity. Principal component analysis was employed to build a physical fitness age score based on motor function variables. Validation test showed that the physical fitness age in the exercised older women was significantly lower than their chronological age, while no significant difference was observed between the physical fitness age and the chronological age in the normal elderly. The findings suggest that physical fitness age score is a valid approach to evaluate motor function in Chinese community-dwelling elderly women.

Sex differences in heel pad stiffness during in vivo loading and unloading.

Due to conflicting data from previous studies a new methodological approach to evaluate heel pad stiffness and soft tissue deformation has been developed. The purpose of this study was to compare heel pad (HP) stiffness in both limbs between males and females during a dynamic unloading and loading activity. Ten males and 10 females volunteered to perform three dynamic trials to unload and load the HP. The dynamic protocol consisted of three continuous phases: foot flat (baseline phase), bilateral heel raise (unloading phase) and foot flat (loading phase) with each phase lasting two seconds. Six retroreflective markers (3 mm) were attached to the skin of the left and right heels using a customised marker set. Three-dimensional motion analysis cameras synchronised with force plates collected the kinematic and kinetic data throughout the trials. Three-way repeated measures ANOVA together with a Bonferroni post hoc test were applied to the stiffness and marker displacement datasets. On average, HP stiffness was higher in males than females during the loading and unloading phases. ANOVA results revealed no significant differences for the stiffness and displacement outputs with respect to sex, sidedness or phase interactions (p > .05) in the X, Y and Z directions. Irrespective of direction, there were significant differences in stiffness between the baseline and unloading conditions (p < .001) but no significant differences between the baseline and loaded conditions (p = 1.000). Post hoc analyses for the marker displacement showed significant differences between phases for the X and Z directions (p < .032) but no significant differences in the Y direction (p > .116). Finally, females portrayed lower levels of mean HP stiffness whereas males had stiffer heels particularly in the vertical direction (Z) when the HP was both unloaded and loaded. High HP stiffness values and very small marker displacements could be valuable indicators for the risk of pathological foot conditions.

The Evaluation of Bone Mineral Density based on Age and Anthropometric Parameters in Southeast Chinese Adults: A Cross-Sectional Study.

BACKGROUND Osteoporosis is a chronic skeletal disease characterized by a reduction in bone density, resulting in high death rates and high costs among patients worldwide. This study investigated the associations among age, anthropometric parameters and bone mineral density (BMD) in southeast Chinese adults and evaluated the characteristics of southeast Chinese adults at high risk of osteoporosis. MATERIAL AND METHODS This study enrolled 424 female and 265 male volunteers. Height, weight and BMD were measured, and body mass index (BMI) was calculated. Based on their BMD T-scores, female and male participants were divided into groups with osteoporosis (OG1) and osteopenia (OG2) and a normal group (NG). RESULTS The findings revealed no significant correlations between BMD and anthropometric parameters in either gender. However, a significant negative correlation was noted between BMD and age in the female participants, and a significant positive correlation was observed between BMD and age in the male participants. Multiple comparisons between groups revealed that women in the OG1 and OG2 groups were significantly older than those in the NG group. CONCLUSIONS Age, anthropometric parameters and BMD correlate differently between groups and genders in southeast Chinese adults.

Differences in the magnitude and reliability of velocity variables collected during 3 variants of the bench press exercise.

This study aimed to compare the reliability and magnitude of velocity variables between 3 variants of the bench press (BP) exercise in participants with and without BP training experience. Thirty males, 15 with and 15 without BP experience, randomly performed 3 variants of the BP on separate sessions: (I) concentric-only, (II) fast-eccentric and (III) controlled-eccentric. The mean velocity (MV) and maximum velocity (Vmax) of the concentric phase were collected against 3 loads (≈30%1RM, 50%1RM, and 75%1RM) with a linear velocity transducer. Reliability was high regardless of the variable, BP variant, and load (coefficient of variation [CV] ≤ 4.47%, intraclass correlation coefficient [ICC] ≥ 0.87). The comparison of the CVs suggested a higher reliability for the fast-eccentric BP (8 out of 12 comparisons), followed by the concentric-only BP (5 out of 12 comparisons), and finally the controlled-eccentric BP (never provided a higher reliability). No differences in reliability were observed between experienced (CV ≤ 4.71%; ICC ≥ 0.79) and non-experienced (CV ≤ 6.29%; ICC ≥ 0.76) participants. The fast-eccentric BP provided the highest MV (p < 0.05) and no differences were observed for Vmax. These results support the assessment of movement velocity during the fast-eccentric BP even in participants without experience.

The Influence of Gender, Age, and Body Mass Index on Arch Height and Arch Stiffness.

Arch structure and arch function play an important role in maintaining balance, bearing body weight, and absorbing ground reaction forces. However, arch structure and arch function are known to vary extensively and may be affected by factors such as gender, age, and obesity. Therefore, the purpose of this study was to examine the influence of gender, age, and body mass index (BMI) on arch height and arch stiffness. A total of 173 participants (aged 57.60 ± 11.19 years, mean BMI 25.12 ± 3.93 kg/m2) participated in this cross-sectional study. A 3-dimensional laser scanner was used to measure foot structure information in each subject, from which arch height and arch stiffness were calculated. The results showed that women had low-arched feet compared with men (p = .001), and no arch stiffness difference was found. Older individuals tended to have a stiffer arch than middle-aged and younger individuals (p < .05), and no arch height difference was found. BMI had an impact on arch height (p < .05) but not arch stiffness. Finally, a weak positive relationship existed between arch height and arch stiffness (r = 0.32, p < .01). The findings suggest that gender, age, and obesity have a certain impact on arch structure and arch stiffness. Figuring out the relationship between these factors and arch structure may be helpful in understanding the bases of foot deformity and foot dysfunction.

Comparing the Kinematic Characteristics of the Lower Limbs in Table Tennis: Differences between Diagonal and Straight Shots Using the Forehand Loop.

The diagonal shot (DS) and straight shot (SS) using the forehand loop are the most common techniques used in table tennis. The purpose of this study was to investigate the kinematic differences of the lower limbs between DS and SS. Twelve male table tennis athletes performed DS and SS in random order. Kinematic data were captured using a three-dimensional Vicon motion analysis system. The major findings of this study were that DS showed significantly less time compared with SS during the backward swing (BS) and the forward swing (FS) phases. Meanwhile, DS showed significantly larger ankle internal rotation and inversion with smaller knee abduction and external rotation during the BS. DS showed significantly larger knee extension with smaller hip adduction and knee internal rotation compared with SS during the FS. However, SS showed a significantly larger range of motion (ROM) of ankle plantar flexion external rotation, and significantly larger ROM of knee extension. Moreover, SS showed significantly larger knee internal rotation compared with DS. These differences between the two shot techniques could be beneficial for helping coaches and table tennis athletes optimize performance, both in training and competition.

Lower Limb Maneuver Investigation of Chasse Steps Among Male Elite Table Tennis Players.

Background and objectives: The popularity of table tennis has increased globally. As a result, the biomechanical movement patterns in the lower limb during table tennis have attracted extensive attention from coaches, scientists and athletes. The purpose of this study was to compare the differences between the long and short chasse steps in table tennis and evaluate risk factors related to injuries in the lower limb. Materials and Methods: Twelve male elite athletes performed forehand topspin strokes with long and short chasse steps in this study, respectively. The kinematics data of the lower-limb joints were measured by a Vicon motion analysis system. The electromyograms (EMG) of six lower-limb muscles were recorded using a myoelectricity system. Results: The key findings were that the angle change rate of the ankle in the long chasse step was faster with a larger range of motion (ROM) in the coronal and transverse planes. The hip was also faster in the sagittal and transverse planes but slower in the coronal plane compared with the short chasse step. In addition, the vastus medialis (VM) was the first activated muscle in the chasse step. Conclusions: The hip and ankle joints in the long chasse step and the knee joint in the short chasse step have higher susceptibility to injury. Moreover, tibialis anterior (TA), vastus medialis (VM) and gastrocnemius (GM) should be sufficiently stretched and warmed prior to playing table tennis. The results of this study may provide helpful guidance for teaching strategies and providing an understanding of potential sport injury mechanisms.

Electromyographic analyses of the erector spinae muscles during golf swings using four different clubs.

The purpose of this study was to compare the electromyography (EMG) patterns of the thoracic and lumbar regions of the erector spinae (ES) muscle during the golf swing whilst using four different golf clubs. Fifteen right-handed male golfers performed a total of twenty swings in random order using the driver, 4-iron, 7-iron and pitching-wedge. Surface EMG was recorded from the lead and trail sides of the thoracic and lumbar regions of the ES muscle (T8, L1 and L5 lateral to the spinous-process). Three-dimensional high-speed video analysis was used to identify the backswing, forward swing, acceleration, early and late follow-through phases of the golf swing. No significant differences in muscle-activation levels from the lead and trail sides of the thoracic and lumbar regions of the ES muscle were displayed between the driver, 4-iron, 7-iron and pitching-wedge (P > 0.05). The highest mean thoracic and lumbar ES muscle-activation levels were displayed in the forward swing (67-99% MVC) and acceleration (83-106% MVC) phases of the swing for all clubs tested. The findings from this study show that there were no significant statistical differences between the driver, 4-iron, 7-iron and pitching-wedge when examining muscle activity from the thoracic and lumbar regions of the ES muscle.