Badminton is the fastest racket sport in the world with smash speeds reaching over 111 m/s (400 kph). This study examined the forehand jump smash in badminton using synchronised force plates and full-body motion capture to quantify contributions to shuttlecock speed through correlations. Nineteen elite male Malaysian badminton players were recorded performing forehand jump smashes with the fastest, most accurate jump smash from each player analysed. The fastest smash by each participant was on average 97 m/s with a peak of 105 m/s. A correlational analysis revealed that a faster smash speed was characterised by a more internally rotated shoulder, a less elevated shoulder, and less extended elbow at contact. The positioning of the arm at contact appears to be critical in developing greater shuttlecock smash speeds. Vertical ground reaction force and rate of force development were not correlated with shuttlecock speed, and further investigation is required as to their importance for performance of the jump smash e.g. greater jump height and shuttle angle. It is recommended that players / coaches focus on not over-extending the elbow or excessively elevating the upper arm at contact when trying to maximise smash speed.

Acute physiological, perceptual and biomechanical consequences of manipulating both exercise intensity and hypoxic exposure during treadmill running were determined. On separate days, eleven trained individuals ran for 45 s (separated by 135 s of rest) on an instrumented treadmill at seven running speeds (8, 10, 12, 14, 16, 18 and 20 km.h −1 ) in normoxia (NM, FiO 2 = 20.9%), moderate hypoxia (MH, FiO 2 = 16.1%), high hypoxia (HH, FiO 2 = 14.1%) and severe hypoxia (SH, FiO 2 = 13.0%). Running mechanics were collected over 20 consecutive steps (i.e. after running ∼25 s), with concurrent assessment of physiological (heart rate and arterial oxygen saturation) and perceptual (overall perceived discomfort, difficulty breathing and leg discomfort) responses. Two-way repeated-measures ANOVA (seven speeds × four conditions) were used. There was a speed × condition interaction for heart rate (p = 0.045, ηp 2 = 0.22), with lower values in NM, MH and HH compared to SH at 8 km.h −1 (125 ± 12, 125 ± 11, 128 ± 12 vs 132 ± 10 b.min −1 ). Overall perceived discomfort (8 and 16 km.h −1 ; p = 0.019 and p = 0.007, ηp 2 = 0.21, respectively) and perceived difficulty breathing (all speeds; p = 0.023, ηp 2 = 0.37) were greater in SH compared to MH, whereas leg discomfort was not influenced by hypoxic exposure. Minimal difference was observed in the twelve kinetics/kinematics variables with hypoxia (p > 0.122; η p 2 = 0.19). Running at slower speeds in combination with severe hypoxia elevates physiological and perceptual responses without a corresponding increase in ground reaction forces. Highlights. The extent to which manipulating hypoxia severity (between normoxia and severe hypoxia) and running speed (from 8 to 20 km.h −1 ) influence acute physiological and perceptual responses, as well as kinetic and kinematic adjustments during treadmill running was determined. . Running at slower speeds in combination with severe hypoxia elevates heart rate, while this effect was not apparent at faster speeds. . Arterial oxygen saturation was increasingly lower as running speed and hypoxic severity increased. . Overall perceived discomfort (8 and 16 km.h −1 ) and perceived difficulty breathing (all speeds) were lower in moderate hypoxia than in severe hypoxia, whereas leg discomfort remained unchanged with hypoxic exposure.

Three-dimensional position data of nineteen elite male Malaysian badminton players performing a series of maximal jump smashes were collected using a motion capture system. A ‘resultant moments’ inverse dynamics analysis was performed on the racket arm joints (shoulder, elbow and wrist). Relationships between racket head speed and peak joint moments were quantified using correlational analyses, inclusive of a Benjamini–Hochberg correction for multiple-hypothesis testing. The racket head centre speed at racket–shuttlecock contact was, on average, 61.2 m/s with a peak of 68.5 m/s which equated to average shuttlecock speeds of 95.2 m/s with a peak of 105.0 m/s. The correlational analysis revealed that a larger shoulder internal rotation moment (r = 0.737), backwards shoulder plane of elevation moment (r = 0.614) and wrist extension moment (r = −0.564) were associated with greater racket head centre speed at racket–shuttlecock contact. Coaches should consider strengthening the musculature associated with shoulder internal rotation, plane of elevation and wrist extension. This work provides a unique analysis of the joint moments of the racket arm during the badminton jump smash performed by an elite population and highlights significant relationships between racket head speed and peak resultant joint moments.

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INTRODUCTION: Mobile video gaming among university students has increased rapidly, more than before the COVID-19 pandemic. This is very concerning as this could spark various problems, such as musculoskeletal pain and gaming disorders. OBJECTIVES:  The present study is to identify the predictors of mobile video gaming on musculoskeletal pain among university students in Selangor, Malaysia. PARTICIPANTS AND METHODS: This study was conducted online using a self-reported online questionnaire via Google Form and sent to university students in Selangor, Malaysia. Participants' gaming addiction was measured using the Ten Item Internet Gaming Disorder Test (IGDT-10) questionnaire, and the prevalence of musculoskeletal pain was assessed by the Modified Nordic Musculoskeletal Questionnaire (MNMQ). The data was analyzed using SPSS version 25. A descriptive and binomial linear regression test was used to predict the variables. The statistical significance was set at p < 0.05, and odds ratios were calculated with confidence intervals of 95%. RESULTS: The prevalence of Internet Gaming Disorder among university students in Selangor, Malaysia is 1.8% (n=3). The neck region (74.2%) was the most commonly reported body region with musculoskeletal pain, followed by the shoulder region (60.7 %), lower back region (55.8 %), and upper back region (50.9 %). The body position was the only predictor of mobile video gaming with musculoskeletal pain (p = 0.002) in the lower back region. CONCLUSION: According to the findings of this study, the prevalence of Internet Gaming Disorder (IGD) among university students was low and not addicted to gaming in the Covid-19 lockdown. We also found that participants who sat while playing mobile video games were more likely to develop low back pain. However, one of the limiting factors could be prolonged sitting in virtual classes during the lockdown, which causes low back pain.

Studies evaluating mechanical asymmetry across a range of running velocities during treadmill runs have yielded inconsistent findings, while the impact of additional hypoxic exposure has never been investigated. The aim of this study was to characterize the effects of manipulating running velocity and hypoxic exposure on gait asymmetry during treadmill running. Eleven trained individuals performed seven runs at different velocities (8, 10, 12, 14, 16, 18, and 20 km·h−1) in a randomized order, each lasting 45 s. The running took place on an instrumented treadmill for normoxia (FiO2 = 20.9%), moderate hypoxia (FiO2 = 16.1%), high hypoxia (FiO2 = 14.1%), and severe hypoxia (FiO2 = 13.0%). Vertical and antero-posterior ground reaction force recordings over 20 consecutive steps (i.e., after running ∼25 s) allowed the measurement of running mechanics. Lower-limb asymmetry was assessed from the ‘symmetry angle’ (SA) score. Two-way repeated-measures ANOVA (seven velocities × four conditions) was used. There was no significant difference in SA scores for any of the biomechanical variables for velocity (except contact time and braking phase duration; p = 0.003 and p = 0.002, respectively), condition, or interaction. Mean SA scores varied between ∼1% and 2% for contact time (1.5 ± 0.8%), flight time (1.6 ± 0.6%), step length (0.8 ± 0.2%), peak vertical force (1.2 ± 0.5%), and mean vertical loading rate (2.1 ± 1.0%). Mean SA scores ranged from ∼2% to 5% for duration of braking (1.6 ± 0.7%) and push-off phases (1.9 ± 0.6%), as well as peak braking (5.0 ± 1.9%) and push-off forces (4.8 ± 1.7%). In conclusion, the trained runners exhibited relatively even strides, with mechanical asymmetries remaining low-to-moderate across a range of submaximal, constant running velocities (ranging from 8 to 20 km·h−1) and varying levels of hypoxia severity (between normoxia and severe hypoxia).

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