Search

The purpose of this study was to explore the experiential knowledge of tennis coaches as it related to the development of grip positions in tennis athletes. Accredited tennis coaches (n = 11) completed semi-structured interviews consisting of open-ended questions about their coaching background, the importance of grip positions compared with other areas of foundational development, and their opinions on using physically-constraining tools (PCTs). Two major themes, "Grip positions are an adaptive skill" and "Why and how do I modify an athlete's grip?", were identified. Coaches expressed the opinion that grip positions were dynamic and a modifiable component of tennis stroke technique. Irrespective of shot type, grip positions were viewed as a non-negotiable aspect of talent development and intrinsically linked to other components of the stroke. Coaches questioned the necessity of technique refinement for grip positions given the complex and time-costly nature of bringing about effective motor-behaviour change. Some coaches expressed reservations about skill transfer into live match-play, intuitively expressing the concepts of the constraints-led approach to manipulate key variables within the athlete's environment to foster learning. Future research should aim to assess the short- and long-term effects of PCT use in tennis and establish the extent to which PCTs can impact learning and skill transfer. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the physiological, perceptual, and biomechanical differences between male and female soldiers across several military-relevant load and walking speed combinations. Eleven female and twelve male soldiers completed twelve 12 min walking trials at varying speeds (3.5 km·h−1, 5.5 km·h−1, 6.5 km·h−1) and with varying external loads (7.2 kg, 23.2 kg, 35.2 kg). Physiological (indirect calorimetry, heart rate), perceptual (perceived exertion), and biomechanical (spatiotemporal, kinematic, kinetic) outcomes were measured throughout each trial. Females had a lower aerobic capacity and lower body strength than males, which resulted in them working at a greater exercise intensity (%VO2peak and heart rate) but with a lower oxygen pulse. Females demonstrated higher breathing frequency and perceived exertion with specific loads. At selected loads and speeds, frontal and sagittal pelvis, hip, and knee motions and forces were greater for females. Females consistently displayed greater relative stride length and step width. In conclusion, this study demonstrates the importance of tailored interventions, periodisation, and nutritional strategies for female military personnel, given their higher relative work rate and increased injury risk during load carriage tasks. Understanding these differences is crucial for preparing female soldiers for the physical demands of military service. [ABSTRACT FROM AUTHOR]

This study aimed to understand how tennis coaches perceive and approach the development of grip positions, a foundational skill in tennis. Professionally accredited coaches, classed as less (n = 140) or more (n = 86) experienced, participated in an online survey where they provided their perspectives on the importance of developing grip positions and their opinions on using physically constraining tools for coaching. Irrespective of coach experience level, the findings revealed that technique development and grip position training were ranked as the two most important components in foundational tennis skill development. The Semi-western grip for forehand (less: 68%; more: 65%), a combination of Continental and Eastern grips for double-handed backhand (less: 59%; more: 48.8%), and the Continental grip for serves (both: 94%) were identified as the most commonly taught positions for different shots. Perceived barriers to developing grip positions were out of habit (less: 62%; more: 56%), discomfort (less: 58%; more: 50%), and lack of confidence (less: 44%; more: 21%). Notably, 65% of coaches expressed an openness to incorporating physically constraining tools to enhance grip-specific skill development. Overall, this study serves as a foundational resource, guiding coaches in optimising their strategies for foundational tennis development, prompting further research in this area. [ABSTRACT FROM AUTHOR]

Acquisition evaluations are expensive, have a high time liability, and tend to prioritize engineering requirements over human factors and good experimental design. Shooting serials usually consist of static prone shooting to minimize movement variability, increase reliability of accuracy and timing data or use a single data point to make acquisition decisions. To better understand the number of trials required to achieve representative performance of accuracy and timing, 60 shots from the standing unsupported position while cyclically moving the weapon from the low ready to shoot was utilized. Intra‐class correlations, standard error of measurement, minimal detectable change, and sequential averaging analysis (SAA) were used to evaluate the variables of radial error, shot interval, x‐bias and y‐bias over the 60 shots. The number of trials required to achieve an intraclass correlation of greater than 0.8 ranged from 2 (shot interval) to 58 (y‐bias), whereas SAA varied between 3 (x‐bias) and 43 (shot interval) trials. When averaging 10 shots at a time, the moving intraclass correlation remained above 0.8 for radial error and y‐bias between 7 and 15 shots, shot interval from the second shot, but x‐bias never reached 0.8. The number of trials required to satisfy each reliability method was inconsistent, in line with previous literature. Given the limitations identified in the literature as well as practical considerations such as the preference for prioritizing radial error reasonable performance stability can be achieved after 15 shots, and using the moving intraclass correlation results it is recommended that the first six shots are discarded with the following nine shots used for analysis. [ABSTRACT FROM AUTHOR]

There is limited research on the on-field performance of previously concussed athletes. The aim of this exploratory study was to investigate athlete technical performance pre- and post-concussion in Australian Football. Using publicly available data, male athletes who sustained a concussion during the 2016–19 professional Australian Football League seasons were analysed across five games pre- and post-concussion (concussion events n = 41, age 25.4 ± 3.5 years; control n = 39, age 25.2 ± 3.6 years). Mean technical performance metrics (goals, time-on-ground percentage, kicks, ground ball and disposal efficiency, contested marks) over the five games pre- and post-concussion, as well as within-athlete performance variability measures (standard deviation and coefficient of variation) were analysed. Results showed no significant group-by-time interactions, nor effect of time (pre-post) for any technical performance metric. Similarly, the within-athlete standard deviation and coefficient of variation of technical performance metrics showed no group-by-time interaction, nor effect for time. This retrospective study has shown that athlete performance averaged over five games is not affected post-concussion in elite men's Australian Football. Further prospective studies controlling for contextual match factors based on opposition and environmental conditions may be required to identify potential in-game technical performance changes following return-to-play from concussion. [ABSTRACT FROM AUTHOR]

Temporal changes in the total running demands of professional football competition have been well documented, with absolute running demands decreasing in the second half. However, it is unclear whether the peak match running demands demonstrate a similar decline. A total of 508 GPS files were collected from 44 players, across 68 matches of the Australian A-League. GPS files were split into the 1st and 2nd half, with the peak running demands of each half quantified across 10 moving average durations (1-10 min) for three measures of running performance (total distance, high-speed distance [> 19.8 km ⋅ h-1] and average acceleration). Players were categorised based on positional groups: attacking midfielder (AM), central defender (CD), defensive midfielder (DM), striker (STR), wide defender (WD) and winger (WNG). Linear mixed models and effect sizes were used to identify differences between positional groups and halves. Peak running demands were lower in the second half for STR across all three reported metrics (ES = 0.60--0.84), with peak average acceleration lower in the second half for DM, WD and WNG (ES = 0.60--0.70). Irrespective of match half, AM covered greater peak total distances than CD, STR, WD and WIN (ES = 0.60--2.08). Peak high-speed distances were greater across both halves for WIN than CD, DM and STR (ES = 0.78--1.61). Finally, STR had lower peak average acceleration than all positional groups across both halves (ES = 0.60--1.12). These results may help evaluate implemented strategies that attempt to mitigate reductions in second half running performance and inform position specific training practices. [ABSTRACT FROM AUTHOR]

The aim of this study was to understand the association between impact and movement characteristics during whole game and peak 1- to 10-minute rolling windows in professional rugby union. Maximal impact (impacts·min-1) and corresponding running (m·min-1) characteristics as well as maximal running (m·min-1) and corresponding impact (impacts·min-1) characteristics were obtained for 160 athletes from 4 teams across the 2018 and 2019 Super Rugby seasons. A linear mixed-effects model reported a positive association between whole-game running and impacts, where greater impact characteristics corresponded with greater running characteristics. The average 1-minute peak running characteristics (150-160 m·min-1) typically occurred when no impacts occurred. The average 1-minute peak impact characteristics (4-6 impacts·min-1) corresponded with an average relative distance of 90-100 m·min-1. Worst case scenario observed impact characteristics as large as 15 impacts·min-1 with a corresponding relative distance of 140 m·min-1. When training for peak period characteristics, running may be completed in isolation; however, peak impacts often occur in conjunction with moderate to high running movements. Given running and impact characteristics can appear concurrently within game play, this highlights the need to train them accordingly. As such, when prescribing training drills to replicate the peak characteristics in rugby union, consideration should be taken for both running and impact characteristics. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the peak periods (1- to 6-minute epochs) for three different training methods (game-based training – GBT; small-sided games – SSG; and conditioning training – CT) in elite male rugby union (RU) players. The peak movement (m·min−1) and impact (impact·min−1) characteristics of 42 players during in-season training were assessed. When comparing between training methods, SSG drills produced the greatest peak movement characteristics for all time epochs (1-minute average peak periods – SSG 195 m·min−1, GBT 160 m·min−1, and CT 144 m·min−1). The peak impact characteristics performed during training were 1–2 impact·min−1 for a 1-minute period and then decreased as the time period increased for all training methods. The greatest distribution of training time occurred at 30–39% (SSG and CT) and 40–49% (GBT) of peak movement intensity, with less than 5% of training performed at or above 80% peak intensity across all drill types. Findings from the current study show that the peak movement periods (m·min−1) in RU training from all three training methods match or exceed those which are previously reported in peak gameplay, yet their ability to replicate peak impact characteristics is questionable. [ABSTRACT FROM AUTHOR]

The peak match running demands of football (soccer) have been quantified across time durations of 1--10 min, however, little is known as to when the peak match running demands occur within match play. Data were collected from 44 elite footballers, across 68 fixtures (Files = 413, mean ± SD; 11 ± 8 observations per player, range; 1--33), with peak match running demands quantified for each playing half at ten incremental rolling average durations (1 min rolling averages, 2 min rolling averages, etc.). Data were assessed if players completed the full match. Three measures of running performance were assessed total distance (TD), highspeed distance (> 19.8 km · h-1) (HSD) and average acceleration (AveAcc)], with the in-game commencement time of the peak running demands recorded. Descriptive statistics and normality were calculated for each rolling average duration, with the self-containment of shorter rolling average epochs within longer epochs also assessed (e.g. Do the 1 min peak running demands occur within the 10 min peak running demands). Peak TD and AveAcc demands occurred early in each half (median time = 7--17 min and 6--16 min, respectively). Conversely, peak HSD covered was uniformly distributed (Skewness = 0--0.5, Kurtosis = 1.7--2.0). There were low-moderate levels of self-containment for each peak match running period (10--51%), dependent upon metric. Peak match running demands for TD and AveAcc occurred at similar stages of a match where TD and acceleration volumes are typically greatest, whereas peak HSD demands appeared more unpredictable. These timings may help inform training prescriptions in preparation of athletes for competition. [ABSTRACT FROM AUTHOR]

Peak match running intensities have recently been introduced to quantify the peak running demands of football competition, across incremental time intervals, to inform training practices. However, their between-match variation is yet to be comprehensively reported, limiting the ability to determine meaningful changes in peak match running intensities. The current study aimed to quantify the between-match variability in peak match running intensities across discrete moving average durations (1--10 min). GPS data were collected from 44 elite football players across 68 matches (mean ± SD; 13 ± 10 observations per player). For inclusion players must have completed 70mins of a match across a minimum of two matches. Performance metrics included total and high-speed (> 19.8 km ⋅ h-1) running distances and average acceleration (m ⋅ s-2), expressed relative to time. For each metric, the coefficient of variation and smallest worthwhile difference were calculated. The peak match running intensity data was similar to previously reported data from various football competitions. The between-match CV of relative total distance ranged between 6.8--7.3%, with the CV for average acceleration and relative high-speed running being 5.4--5.8% and 20.6--29.8%, respectively. The greater variability observed for relative high-speed running is likely reflective of the varying constraints and contextual factors that differ between matches. The reported between-match variability helps to provide context when interpreting match performance and prescribing training drills using peak match running intensity data. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare double-handed backhand kinematics of the non-dominant wrist of tennis players using either an eastern or continental grip position with the non-dominant hand. Trajectory data were captured using sixty reflective markers on sixteen sub-elite right-handed tennis players using a 12-camera VICON motion capture system (250 Hz). Participants executed double-handed backhands using two non-dominant grip positions (Eastern [E] and Continental [C]), aiming for two crosscourt zones (Deep [D] and Short [S]), totalling to four conditions (ED, CD, ES and CS). Three successful attempts from each condition were selected for analysis. The eastern grip demonstrated faster horizontal racket head velocity compared to the continental grip. However, no differences were observed in accuracy or spin rate between grips (p > 0.05). In the non-dominant upper limb, elbow flexion was smaller in the continental condition throughout the swing, whilst wrist extension and ulnar deviation was larger. Collectively, these data suggest that the continental grip may place the wrist in a position vulnerable to overuse injury. Future research into the kinetics of the double-handed backhand would help better understand the onset of ulnar-side wrist pain in tennis. [ABSTRACT FROM AUTHOR]

Tredrea, MSJ, Middleton, KJ, Bourne, MN, Carey, DL, Scanlan, AT, and Dascombe, BJ. Load centralization does not affect the kinetic and kinematic output of countermovement jumps. J Strength Cond Res 36(4): 1084-1089, 2022-This study aimed to compare the kinetics, kinematics, and performance of countermovement jumps (CMJs) when completed with 2 different loading conditions (centralized or peripheral) across increasing loads. Seventeen subjects (12 men and 5 women) randomly completed 2 series of CMJs with increasing loads separated by a 30-minute rest period between conditions. Subjects were loaded with either a weighted vest (centralized) or straight barbell (peripheral). A randomized, counterbalanced crossover design was used with incremental loads of 10, 20, 30, 40, and 50% of body mass added to the vest or barbell. Measures of peak force, acceleration, velocity, and power were calculated across each subphase of the CMJs. No significant differences were observed in kinetic or kinematic variables between loading conditions. Within each condition there were significant reductions (p < 0.05) in peak concentric velocity and acceleration, as well as significant increases (p < 0.05) in peak force when the external load increased. Furthermore, braking and propulsive phase duration significantly increased (p < 0.05) and jump height significantly decreased (p < 0.05) as the external load increased. Countermovement jump performance was similar in both central and peripheral loading, whereas increasing load significantly affected jump height, force, velocity, and acceleration variables irrespective of load position. The training stimulus from an external load placed centrally or peripherally is similar regardless of where it is positioned; however, from a practical perspective, a weighted vest may provide a more mobile and safer alternative than a barbell. [ABSTRACT FROM AUTHOR]

Wearable microtechnology is effective in detecting fast deliveries in cricket, however methods to quantify delivery intensity have not been established. This study aimed to investigate the utility of wearable sensors in quantifying cricket fast bowling intensity. Fifteen sub-elite male fast bowlers performed deliveries at warm-up, match, and maximal intensities. A principal component analysis resulted in the selection of perceived exertion and seven variables of bowling exertion derived from trunk- (PlayerLoad™, trunk flexion velocity, trunk forward rotation velocity) and tibia-mounted (tibial acceleration at back foot contact, front foot contact, back foot re-contact and front foot re-contact) inertial measurement units for further analysis. Repeated measures ANOVAs were used to investigate the effect of intensity on outcome variables. Significant main effects of intensity and large effect sizes were identified for all variables (p <.05, np2 > 0.14). Measures from the match and maximal conditions were significantly larger compared with the warm-up condition (Pholm <.05). No differences were observed between the match and maximal conditions (p >.05). Inertial measurement metrics can distinguish between a warm-up effort and both match and maximal fast bowling delivery intensity. These devices provide a unique, time-efficient approach to cricket fast bowling exertion quantification. [ABSTRACT FROM AUTHOR]

This study compared physiological and biomechanical responses between treadmill and overground load carriage. Thirty adults completed six 10-minute walking trials across three loads (0, 20, and 40% body mass) and two surfaces (treadmill and overground). Relative oxygen consumption was significantly greater on the treadmill for 20% (1.54 ± 0.20 mL⋅kg−1⋅min−1) and 40% loads (1.08 ± 0.20 mL⋅kg−1⋅min−1). All other physiological and perceptual responses were significantly higher in the treadmill condition and with increases in load. Stance time was longer (0%: 0.05 s; 20%: 0.02 s, 40%: 0.05 s, p < 0.001) and cadence was lower (0%: 1 step·min−1; 20%: 2 steps·min−1; 40%: 3 steps·min−1, p < 0.05) on the treadmill. Peak lower limb joint angles were similar between surfaces except for ankle plantar flexion, which was 8˚ greater on the treadmill. The physiological responses to treadmill-based load carriage are generally not transferable to overground load carriage and caution must be taken when conducting treadmill-based load carriage research to inform operational-based scenarios. Practitioner Summary: Literature is limited when comparing the physiological and biomechanical responses to treadmill and overground load carriage. Using a repeated measures design, it was shown that although walking kinematics are generally similar between surfaces, there was a greater physiological demand while carrying a load on a treadmill when compared with overground. Abbreviations: BM: body mass; e.g: for example; HR: heart rate; HRmax: heart rate maximum; Hz: hertz; kg: kilograms; km·h−1: kilometres per hour; L⋅min−1: litres per minute; m: metres; MD: mean difference; mL·kg−1·min−1: millilitres per kilogram per minute; mL⋅min−1: millilitres per minute; η2p: partial-eta squared; OG: overground; RPE: rating of perceived exertion; s: seconds; SD: standard deviation; SE: standard error; steps·min−1: steps per minute; TM: treadmill; V̇CO2: volume of carbon dioxide; V̇E: ventilation; V̇O2: volume of oxygen; V̇O2max: maximum volume of oxygen; y: years [ABSTRACT FROM AUTHOR]

Defence acquisitions use accuracy measures as a discriminating factor in weapon purchases, but assessments are generally completed in static, supported postures at static targets with few differences being seen between configurations. The aim of this study was to investigate whether an assessment requiring repositioning between shots could reveal differences. Participants shot at a static target under four conditions: an unweighted rifle and the addition of a mass fixed at three different positions. Accuracy and timing as well as discomfort measures were captured and compared. Hit percentage, consistency and timing varied over time, and timing increased with the addition of mass in two out of the three conditions. There was an increase in discomfort with the addition of mass further from the participant. The results showed that relying on accuracy and consistency measures alone to make acquisition decisions could have the consequence of purchasing equipment not fit for the human. Practitioner Summary: This research shows that relying on accuracy and consistency measures alone to make weapon–system acquisition decisions could have the consequence of purchasing equipment not fit for the user. Further research should focus on 'upstream' issues such as muscle fatigue and aim point stability in order to better understand human–weapon–system interactions. [ABSTRACT FROM AUTHOR]