A logarithmic curve fitting methodology for the calculation of badminton racket-shuttlecock impact locations from three-dimensional motion capture data was presented and validated. Median absolute differences between calculated and measured impact locations were 3.6 [IQR: 4.4] and 3.5 [IQR: 3.5] mm mediolaterally and longitudinally on the racket face, respectively. Three-dimensional kinematic data of racket and shuttlecock were recorded for 2386 smashes performed by 65 international badminton players, with racket-shuttlecock impact location assessed against instantaneous post-impact shuttlecock speed and direction. Mediolateral and longitudinal impact locations explained 26.2% (quadratic regression; 95% credible interval: 23.1%, 29.2%; BF10 = 1.3 × 10131, extreme; p < 0.001) of the variation in participant-specific shuttlecock speed. A meaningful (BF10 = ∞, extreme; p < 0.001) linear relationship was observed between mediolateral impact location and shuttlecock horizontal direction relative to a line normal to the racket face at impact. Impact locations within one standard deviation of the pooled mean impact location predict reductions in post-impact shuttlecock speeds of up to 5.3% of the player’s maximal speed and deviations in the horizontal direction of up to 2.9° relative to a line normal to the racket face. These results highlight the margin for error available to elite badminton players during the smash.

Using game-level data, this study examines what impact the mid-season winter break in football fixtures has on technical performance across European football leagues. Thirty-eight technical measures pertaining to the actions of passing and shooting are assessed for 3494 team match observations from the German Bundesliga, Spanish La Liga, French Ligue 1 and English Premier League across 5 seasons from 2013/14 to 2017/18. Kruskal–Wallis tests were conducted to investigate the differences between three groups: PREPRE (4–6 fixtures prior to the break); PRE (1–3 fixtures prior to the break); and POST (1–3 fixtures after the break). Shooting performance declined significantly post winter break in the German Bundesliga (13/21 metrics) which had an average break of 32 days. Passing performance deteriorated significantly in the French Ligue 1 (4/17 metrics) which had an average break of 19 days. The Spanish La Liga had a 13-day break on average and remained unaffected as did the English Premier League which had no mid-season break. Evidence suggests that a mid-season winter break of less than 13 days will not affect technical performance levels but breaks that last longer can act as a catalyst that halt momentum and cause performances to deteriorate.

To compare demands of national netball umpires between levels of competition, 22 Netball New Zealand high-performance umpires participated in this investigation. These included from highest to lowest standard: 9 × semi-professional ANZ Championships (ANZC); 6 × National A Squad (NZA); and 7 × National Development Squad (DEV). Physical (global positioning system tri-axial accelerometry), physiological (heart rate) and technical (video analysis) demands were determined for 48 (16 per group) umpire match performances. Level of competition had no significant effect on physical or mean physiological demands. However, ANZC umpires spent a lower proportion of time at low heart rates compared to DEV, and a greater proportion of time at high, rather than moderate, heart rates compared to NZA. Compared to lower standard umpires, ANZC spent lesser proportions of time standing but greater proportions of time walking backwards and sideways, and turning to change direction. Furthermore, ANZC umpires spent lower proportions of time jogging, but greater proportions of time sprinting compared to DEV. Finally, ANZC umpires spent longer mean durations than DEV on the goal third side line. As such, the difference in demands experienced by national netball umpires between levels of competition is more technical than physical or physiological.

INTRODUCTION: The forehand smash in badminton is a skill which requires elite performers to gauge and determine the most appropriate speed-accuracy trade-off (SATO) given the task, environment and individual constraints (1, 2). Fitts’ law (3) has often been characterised as an adept model for understanding SATO. Manipulation of constraints such as a target for accuracy has become a common coaching practise (4). The aim of this study is to determine and compare what SATO relationships international badminton players utilise when confronted with three constraint practises: maximal speed (MS) towards the direction of a target; maximal speed aiming to hit the centre of three shuttlecock tubes (TUBE); and maximal speed aiming to hit the centre of a circular target placed flat on the ground (TAR). METHODS: Fifty-two (males:29; females:23) international badminton players training/competing at the Glasgow BWF World Championships (2017) participated in the study. Racket-shuttlecock kinematics were collected using a Vicon 3D Motion Analysis System (400 Hz; OMG Plc, Oxford, UK). A ⌀ 3m target (Podium 4 Sport) was placed flat on the centre line of the opposite side of the court to score accuracy (zero: centre circle=most accurate; five: out of bounds/net=least accurate) (5). Using percentage (TUBE;TAR) of MS shuttlecock speed and accuracy score, a combination of two twostep cluster analyses (IBM SPSS V23) were used to identify clusters. A mixed ANOVA was used to analyse group*constraint interaction. RESULTS: Three SATO relationships with different magnitudes (high (H): < 90%; moderate (M): 90-97%; low (L): > 97%) were identified in the cluster analyses: Inverse relationship (IR): decrease in shuttlecock speed, improvement in spatial accuracy; Alternative inverse relationship (AIR): shuttlecock speed increases, decline in spatial accuracy; Linear relationship (LR): Increase in shuttlecock speed, improvement in spatial accuracy. Clusters were combined (TUBE:TAR) to create 5 groupings: HIR:HIR; HIR:MIR; LLR:MIR; LLR:LLR; AIR:AIR. The mixed ANOVA revealed that group shuttlecock speed and accuracy score significantly differed across constraints (p < 0.001). The LLR:MIR group increased shuttlecock speed and improved spatial accuracy the most from the MS to the TUBE condition. CONCLUSION: Elite badminton players adopt different SATO relationships when attempting to meet task constraint goals. A LLR can be used to produce fast and accurate smashes. Controlled constraint practises must be compared to those which incorporate more complex inter-personal dyadic interactions for both singles and doubles badminton.

Purpose: To investigate the post-activation potentiation (PAP) effects of different eccentricoverload (EOL) exercise volumes on countermovement jump (CMJ) and standing long jump (LJ) performance. 89 Methods: Thirteen male university soccer players participated in a cross over design study following a familiarization period. Control (no PAP) CMJ and LJ performances were recorded, and three experimental protocols were performed in a randomized order: 1, 2 or 3 sets of 6 repetitions of flywheel EOL half-squats (inertia=0.029 kg·m2). Performance of CMJ and LJ were measured at 3 and 6 min following all experimental conditions. The time course and magnitude of the PAP were compared between conditions. Results: Meaningful positive PAP effects were reported for CMJ after 2 (Bayes factor [BF10]=3.15, moderate) and 3 (BF10=3.25, moderate) sets but not 1 set (BF10=2.10, anecdotal). Meaningful positive PAP effects were reported for LJ after 2 (BF10=3.05, moderate) and 3 (BF10=3.44, moderate) sets but not 1 set (BF10=0.53, anecdotal). Two and three set protocols resulted in meaningful positive PAP effects on both CMJ and LJ after 6 but not 3 min. Conclusion: This study reported beneficial effects of multiple-set eccentric overload exercise over a single set. A minimum of two sets of flywheel EOL half-squats are required to induce PAP effects on CMJ and LJ performance of male university soccer players. Rest intervals of around 6 min (greater than 3 min) are required to maximize the PAP effects via multiple sets of EOL exercise. However, further research is needed to clarify the optimal EOL protocol configurations for PAP response.