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Ascertaining how racket orientation angle differences at ball-impact influence the accuracy of different squash strokes could assist player skill development and possibly reduce the number of unforced errors hit within a match. The purpose of this study was to identify differences in racket orientation angles of accurate and inaccurate forehand and backhand drive, volley and drop shots. A magnetic-inertial measurement unit embedded in a racket output orientation angles of twelve male junior players, with five accurate and five inaccurate shots per player per stroke analysed. Paired samples t-tests revealed that inaccurate backhand drop shots exhibited significantly (p < 0.05) less racket roll angle (racket face less open) at impact than accurate shots, indicating this parameter was a determining factor in the accuracy of this stroke. Racket orientation angle differences between accurate and inaccurate shots of the remaining strokes were too small to be used to distinguish shot accuracy. There was significantly greater variability in racket orientation angles during inaccurate forehand drop and backhand drive shots compared to accurate shots. These findings demonstrate how racket orientation angle differences at ball-impact can influence the accuracy of shots and highlights the need for consistent racket orientations to allow for an accurate shot. [ABSTRACT FROM AUTHOR]

The torso muscles play important roles in longitudinal rotation between the upper and lower torso on land but demands on these muscles at different swimming speeds and their role in torso twist in front crawl remains unclear. We aimed to compare torso muscle activity at different front crawl speeds and to assess the relationships between torso muscle activity and torso twist. Three-dimensional kinematics and torso muscle EMG data were collected from 15 male swimmers during middle-distance and sprint front crawl. Internal oblique, external oblique, and rectus abdominis, but not erector spinae, activities were greater at sprint than middle-distance pace. Sprint swimmers are likely to benefit from focusing training on the abdominal muscles. Cross-correlation peak coefficients between muscle activity and torso twist occurred with 517–775 and 400–600 ms lag at middle-distance and sprint paces (respectively). These lags are beyond the torso muscle electromechanical delay (~220 ms) and are too long for these muscles to produce movement changes. Further, peak coefficients coincided with both positive and negative shifts, indicating that muscle activity did not always precede kinematic changes. The torso muscles are therefore likely to play a greater role in maintaining stability and controlling posture in front crawl than producing torso twist. [ABSTRACT FROM AUTHOR]

Springboard diving training is often focused upon skill repetition to establish movement accuracy, stability and consistency. Within-participant study designs provide the ability to understand how individuals create these skills under different movement strategies. IMUs measured angular velocity time-series data of two athletes performing multiple repetitions of forward 3½ somersault pike dives. Functional Principal Component Analyses (fPCA) were performed to examine individual movement structure and variability. The first five fPC's represented approximately 98% of the variability in angular velocity for both divers. To determine the relative importance of angular velocity variability, Pearson's correlations for pairwise comparisons were used to assess the relationship between fPC scores and discrete performance variables during takeoff, flight and entry. Divers exhibited a different number and types of significant correlations (International = 4; National = 11). Only one correlation was common for both divers; higher angular velocity during Initial Flight and/or Somersault phases resulted in more vertically aligned entry posture (International: fPC1 r = −0.761, p < 0.05; National: fPC3 r = −0.796, p < 0.01). Findings identify individualised angular velocity time-series structure and kinematic performance variables (International = angular; National = linear) that can be used by coaching/sport science teams to optimisation performance success. [ABSTRACT FROM AUTHOR]

Knowledge of the kinematic differences that separate highly skilled and less-skilled squash players could assist the progression of talent development. This study compared trunk, upper-limb and racket kinematics between two groups of nine highly skilled and less-skilled male athletes for forehand drive, volley and drop strokes. A 15-camera motion analysis system recorded three-dimensional trajectories, with five shots analysed per participant per stroke. The highly skilled group had significantly (p < 0.05) larger forearm pronation/supination range-of-motion and wrist extension angles at impact than the less-skilled. The less-skilled group had a significantly more "open" racket face and slower racket velocities at impact than the highly skilled. Rates of shoulder internal rotation, forearm pronation, elbow extension and wrist flexion at impact were greater in the drive stroke than in the other strokes. The position of the racket at impact in the volley was significantly more anterior to the shoulder than in the other strokes, with a smaller trunk rotation angular velocity. Players used less shoulder internal/external rotation, forearm pronation/supination, elbow and wrist flexion/extension ranges-of-motions and angular velocities at impact in the drop stroke than in the other strokes. These findings provide useful insights into the technical differences that separate highly skilled from less-skilled players and provide a kinematic distinction between stroke types. [ABSTRACT FROM AUTHOR]

To maintain the accuracy of squash shots under varying conditions, such as the oncoming ball's velocity and trajectory, players must adjust their technique. Although differences in technique between skilled and less-skilled players have been studied, it is not yet understood how players vary their technique in a functional manner to maintain accuracy under varying conditions. This study compared 3-dimensional joint and racket kinematics and their variability between accurate and inaccurate squash forehand drives of 9 highly skilled and 9 less-skilled male athletes. During inaccurate shots, less-skilled players hit the ball with a more open racket, demonstrating a difference in this task-relevant parameter. No joint kinematic differences were found for accuracy for either group. Coordinated joint rotations at the elbow and wrist both displayed a "zeroing-in" effect, whereby movement variability was reduced from the initiation of propulsive joint rotation to a higher consistency at ball-impact; potentially highlighting the "functionality" of the variability prior to the impact that enabled consistent task-relevant parameters (racket orientation and velocity) under varying conditions. Further, highly skilled players demonstrated greater consistency of task-relevant parameters at impact than less-skilled players. These findings highlight the superior ability of highly skilled players to adjust their technique to achieve consistent task-relevant parameters and a successful shot. [ABSTRACT FROM AUTHOR]

Dry-land strength training is a common component of swimming programs; however, its efficacy is contentious. A common criticism of dry-land strength training for swimming is a lack of specificity. An understanding of movement patterns in swimming can enable dry-land strength training programs to be developed to elicit adaptations that transfer to improvements in swimming performance. This study aimed to quantify the range and velocity of hip roll, shoulder roll, and torso twist (produced by differences in the relative angle between shoulder roll and hip roll) in front crawl at different swimming speeds. Longitudinal torso kinematics was compared between sprint and 400-m pace front crawl using 3D kinematics of 13 elite Scottish front crawl specialists. The range (sprint: 78.1°; 400 m: 61.3°) and velocity of torso twist (sprint: 166.3°·s; 400 m: 96.9°·s) were greater at sprint than 400-m pace. These differences were attributed to reductions in hip roll (sprint: 36.8°; 400 m: 49.9°) without corresponding reductions in shoulder roll (sprint: 97.7°; 400 m: 101.6°) when subjects swam faster. Shoulder roll velocity (sprint: 190.9°·s; 400 m: 139.2°·s) and hip roll velocity (sprint: 75.5°·s; 400 m: 69.1°·s) were greater at sprint than 400-m pace due to a higher stroke frequency at sprint pace (sprint: 0.95 strokes·s; 400 m: 0.70 strokes·s). These findings imply that torques acting to rotate the upper torso and the lower torso are greater at sprint than 400-m pace. Dry-land strength training specificity can be improved by designing exercises that challenge the torso muscles to reproduce the torques required to generate the longitudinal kinematics in front crawl. [ABSTRACT FROM AUTHOR]

Task-specific auditory training can improve sensorimotor processing times of the auditory reaction time (RT). The majority of competitive swimmers do not conduct habitual start training with the electronic horn used to commence a race. We examined the effect of four week dive training interventions on RT and block time (BT) of 10 male adolescent swimmers (age 14.0 ± 1.4 years): dive training with auditory components (speaker and electronic horn) (n = 5) and dive training without auditory components (n = 5). Auditory stimulus dive training significantly reduced swimming start RT, compared with dive training without auditory components (p < 0.01), with a group mean RT reduction of 13 ± 9 ms. Four of the five swimmers that received auditory stimulus training showed medium to large effect size reductions in RT (d = 0.74; 1.32; 1.40; 1.81). No significant changes to swimmers' BTs were evident in either dive training intervention. The adolescent swimmers' results were compared against six male elite swimmers (age 19.8 ± 1.0 years). The elite swimmers had significantly shorter BTs (p < 0.05) but no significant difference in RTs. Auditory stimulus dive training should be explored further as a mechanism for improving swimming start performance in elite swimmers who have pre-established optimal BTs. [ABSTRACT FROM AUTHOR]

Based on technological and analytical advances, the capability to more accurately and finitely examine biomechanical and skill characteristics of movement has improved. The purpose of this study was to use Inertial Measurement Units (IMUs) and Functional Principal Components Analysis (fPCA) to examine the role of movement variability (assessed via angular velocity), on 2 divers (1 international level; 1 national) performing the forward 3½ pike somersault dive. Analysis of angular velocity curves during ive-flight identified 5 fPCs, accounting for 96.5% of movement variability. The national diver's scatter plots and standard deviation of fPC scores illustrated larger magnitudes of angular velocity variability across dive flight. For fPC1 and fPC3, magnitudes of SD variability were 282.6 and 201.5, respectively. The international diver illustrated more consistent angular velocity profiles, with clustering of fPCs scores (e.g., fPC1 & 3 = SD's of 75.2 & 68.0). To account for lower variability in the international diver, the ability to better coordinate movement sequences and functionally utilise feedback in response to initiation of the somersault position is highlighted. Overall, findings highlight how both IMUs and fPCA can more holistically and finitely examine the biomechanical and skill characteristics of movement sequences with the capability to inform athlete development. [ABSTRACT FROM AUTHOR]

Purpose: Maximum force exertion against various resistance levels (heavy-light) is commonly implemented to improve both strength- and speed-oriented components of power. Medium-light resistances allow rapid accelerations, yet incur significant decelerations in the later concentric phase to bring the bar to a halt, which may limit the concentric effort and, therefore, the effectiveness of training. Accordingly, ballistic actions have been recommended. This study evaluated the effectiveness of power bench press training, with the bar thrown on a Smith machine (BPthrow) or without throwing (BPnon-throw), for developing strength and shot put distance.Methods: Nine university shot-putters performed BPthrow and BPnon-throw at 50, 40 and 30% 1RM, as well as seated and standing shot put trials. Peak angular velocities at the elbow were measured in these tasks using a wireless electro-goniometer. Participants underwent 24 sessions of training (12 weeks) with either BPthrow (n = 5) or BPnon-throw (n = 4) at the three intensities (20 s × 2 sets at 50, 40 and 30% 1RM).Results: The peak elbow velocity during BPthrow was 1.7 times greater than BPnon-throw for all intensities. The velocity of BPthrow at 30% 1RM (854.7°/s), however, was still slower than seated (1121.3°/s) and standing (1539.1°/s) shot puts. BPthrow training significantly improved 1RM (+ 10.0%) and the distances of seated (+ 11.7%) and standing (+ 3.8%) shot puts, while no performance changes occurred after BPnon-throw training.Conclusion: When undergoing power bench press against medium-light resistances, maximum ballistic actions are important strategies for improving 1RM and shot put performance of university shot-putters. [ABSTRACT FROM AUTHOR]

Active drag force in swimming can be calculated from a function of five different variables: swim velocity, tow velocity, belt force, power output and exponent of velocity. The accuracy of the drag force value is dependent on the accuracy of each variable, and on the contribution of each variable to drag estimation. To calculate uncertainty in drag value, first the derivatives of the active drag equation with respect to each variable were obtained. Second, these were multiplied by the uncertainty of that variable. Twelve national age and open level swimmers were recruited to complete four free swimming and five active drag trials. The uncertainties for the free and the tow swim velocities, and for the belt force, contributed approximately 5–6% and 2–3% error, respectively, in calculation of drag. The result of the uncertainty of the velocity exponent (1.8–2.6) indicated a contribution of about 6% error in active drag. The contribution of unequal power output showed that if a power changed 7.5% between conditions, it would lead to about 30% error in calculated drag. Consequently, if a swimmer did not maintain constant power output between conditions, there would be substantial errors in the calculation of active drag. [ABSTRACT FROM AUTHOR]

Inertial Measurement Units (IMUs) may offer an ecologically valid, reliable, and practical method for biomechanical performance analysis. With such potential in mind, Part 1 of this study examined the accuracy of IMUs gyroscopes with an optical system (Cortex 3.3). A calibration formula standardised the IMUs angular velocity output with the optical system. The percentage differences between the two measures = 0.5% (p < 0.05), suggest IMU’s efficacy for application. In Part 2, the aim was to examine and understand how dive flight angular velocity time series plots change and increase according to dive degree of difficulty. With IMUs attached to three competitive divers performing forward somersault dives, dive flight kinematics were assessed. Biomechanically, a 4½ tuck somersault dive differed to lower degree of difficulty dives in terms of: (1) a rotational delay immediately after takeoff (to gain greater vertical translation); (2) increased total time of flight; (3) greater muscle effort to resist increased centrifugal forces produced by the increased angular velocity (1,090 °/s); and (4) greater eccentric control during deceleration allow a safe and vertical entry into the water. IMUs can be effectively utilised and integrated into contexts such as springboard diving for performance analysis and optimisation purposes. [ABSTRACT FROM AUTHOR]

Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling. [ABSTRACT FROM AUTHOR]

The article discusses research investigating both the physiological and physical characteristics of elite dragon boat paddlers. The authors simulated 200-m (meter) and 500-m (meter) dragon boat racing in an attempt to identify characteristics that predict race performance and quantify the metabolic energy contributions. The results of tests measuring maximal accumulated oxygen deficit (MAOD), excess post-exercise oxygen consumption (EPOC), and flexed arm girth in paddlers are discussed.