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Purpose: The study validated variables corresponding to lactate threshold (LT) in swimming. Speed (sLT), blood lactate concentration (BLLT), oxygen uptake (VO2LT), and heart rate (HRLT) corresponding to LT were calculated by 2 different incremental protocols and validated in comparison with maximal lactate steady state (MLSS). Methods: Ten competitive swimmers performed a 7 × 200-m front-crawl incremental "step test" with 2 protocols: (1) with 30-second rests between repetitions (short-rest incremental protocols) and (2) on a 5-minute cycle (swim + rest time, long-rest incremental protocols). Five methods were used for the assessment of sLT and corresponding BLLT, VO2LT, and HRLT: intersection of 2 lines, Dmax, modified Dmax, visual inspection, and intersection of combined linear and exponential regression lines. Subsequently, swimmers performed two to three 30-minute continuous efforts to identify speed (sMLSS) and physiological parameters corresponding to MLSS. Results: Both protocols resulted in similar sLT and corresponding physiological variables (P >.05). Bland–Altman plots showed agreement between protocols (sLT, bias: −0.017 [0.002] m·s−1; BLLT, bias: 0.0 [0.5] mmol·L−1; VO2LT, bias: −0.1 [2.2] mL·kg−1·min−1; HRLT. bias: −2 [8] beats·min−1). However, sLT calculated by modified Dmax using short rest was higher compared with speed at MLSS (1.346 [0.076] vs 1.300 [0.101] m·s−1; P <.05). Conclusions: Calculated sLT, BLLT, VO2LT, and HRLT using all other methods in short-rest and long-rest incremental protocols were no different compared with MLSS (P >.05). Both 7 × 200-m protocols are valid for determination of sLT and corresponding physiological parameters, but the modified Dmax method may overestimate sLT. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to quantify training and match-day (MD) load during 3-, 4-, and 5-day microcycles in professional adult football, as well as to analyze the effect of the microcycle length on training load produced the day after the match (MD + 1) and the day before the match (MD − 1). Methods: The study involved 20 male professional football players whose external and internal loads were monitored for a whole season. The training exposure, total distance covered, high-speed-running distance, sprint distance (SD), individual SD above 80% of the individual maximum velocity (D > 80%), and the number of accelerations and decelerations were quantified, as well as rating of perceived exertion and session rating of perceived exertion training load. Results: Microcycle length affected most of the variables of interest: high-speed-running distance (F = 9.04, P <.01), SD (F = 13.90, P <.01), D > 80% (F = 20.25, P <.01), accelerations (F = 10.12, P <.01), and decelerations (F = 6.01, P <.01). There was an interaction effect between the training day and microcycle type for SD (F = 5.46, P <.01), D > 80% (F = 4.51, P <.01), accelerations (F = 2.24, P =.06), and decelerations (F = 3.91, P <.01). Conclusions: Coaches seem to be influenced by shorter microcycles in their training proposal, preferring sessions with a reduced muscle impact during shorter microcycles. Independent of the length of the congested fixture microcycle, the daily load seems to decrease when MD approaches. [ABSTRACT FROM AUTHOR]

Objective: To analyze the influence of congested and noncongested fixture periods during 2 seasons in a professional male football team on soft-tissue injury incidence and external load. Methods: Thirty-three professional football players from a Portuguese Liga I team participated in this study. Weekly external load and soft-tissue injury rate and burden of 2 consecutive seasons (2021–22 and 2022–23) were analyzed. Results: Total soft-tissue injury rate and burden for the 2 seasons were 3.9 and 3.2 injuries per 1000 hours and 71.8 and 60.5 days per 1000 hours for congested and noncongested periods, respectively. No significant differences were observed between congested and noncongested periods. Total high-speed running, sprint distance, distance above 80% and 90% of maximal velocity, and meters accelerating and decelerating above 2 m/s2 were significantly higher for noncongested weeks. Match accelerations and decelerations above 3 m/s2 were higher during congested periods and training during noncongested periods. No differences between the 2 periods were observed for the total number of accelerations and decelerations above 3 m/s2. Overall, physical outputs per week were higher for training during noncongested weeks, whereas matches during congested periods registered higher external load. Conclusions: No effect of a congested schedule was observed on soft-tissue injury rates and injury burden. Higher match exposure during congested periods increased external load performed per week, and during noncongested periods, training load was superior to congested weeks. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to examine the impact of different rest periods between short sprint interval training (SSIT) trials on the physiological and performance adaptations of female volleyball players. Methods: Twenty-four trained college athletes volunteered to participate in this study and were randomly assigned to 3 SSIT groups with different work-to-rest ratios (1:2 [5-s run:10-s rest], 1:4 [5-s run:20-s rest], and 1:6 [5-s work:30-s rest]). Before and after 6-week training, physiological parameters (maximum oxygen uptake, first and second ventilatory thresholds, and peak and mean power output) and physical performance measures (ie, countermovement vertical jump, 10-m sprint, and T-test change-of-direction speed) were evaluated. Results: After the training period, all groups improved (P =.001) their sport-related performance and physiological parameters, ranging from moderate to very large effect sizes. Comparative analysis of the magnitude of training effects indicated that the 1:6 SSIT group had in a significantly greater change in countermovement vertical jump (P =.007), 10-m sprint (P =.014), peak power output (P =.019), and mean power output (P =.05) compared with 1:2 SSIT group. By contrast, the 1:2 SSIT group demonstrated significantly (P =.022) greater changes in maximum oxygen uptake than the 1:6 SSIT group. However, the change-of-direction speed and changes in first and second ventilatory thresholds were the same among the groups (P >.05). Conclusions: When performing SSIT, longer rest intervals are suitable for physical and anaerobic performance, and shorter rest periods are appropriate for enhancing the cardiorespiratory fitness of female volleyball players' performance. [ABSTRACT FROM AUTHOR]

Purpose: To describe how high-level European sprint coaches (from 100 to 400 m) work to improve important factors associated with the quality of the holistic training process and the quality of the specific training session. Methods: A descriptive analysis was conducted using questionnaires from 31 European elite sprint coaches (ie, training athletes defined as tiers 3, 4, and 5) who participated voluntarily. Results: The coaches used traditional periodization (45%) with a 10- to 15-day tapering phase (48%) that includes a reduction in volume, maintenance of intensity, and focus on correct technical execution. In the 3 mesophases, coaches prioritized the basic development of strength and sprint work in the first phases of the season and emphasized more sprint-specific work in the competitive phase. Before sessions, adjustments were made based on factors such as psychological (77%), technical (48%), and physical (39%) parameters. In-session load management relies on a combination of objective and subjective measures (55%), in which the dialogue with athletes (65%) was regarded as the main resource. Feedback during and after sessions covers technical (54%), psychological (48%), and physical (35%) aspects. Recovery protocols after sessions mainly involve rest and professional guidance (42%). For performance assessment and testing, coaches utilize countermovement jump (52%), force–velocity profile (45%), and 30-m flying (61%) as main tools. Conclusions: European sprint coaches demonstrated a comprehensive approach to planning and management, shedding light on the multifaceted nature of their training methodologies and the diverse tools employed for athlete testing and monitoring. [ABSTRACT FROM AUTHOR]

Purpose: To explore how the change-point method can be used to analyze complex longitudinal data and detect when meaningful changes (change points) have occurred during rehabilitation. Method: This design is a prospective single-case observational study of a football player in a professional club who sustained an acute lower-limb muscle injury during high-speed running in training. The rehabilitation program was entirely completed in the football club under the supervision of the club's medical team. Four wellness metrics and 5 running-performance metrics were collected before the injury and until the player returned to play. Results: Data were collected over 130 days. In the univariate analysis, the change points for stress, sleep, mood, and soreness were located on days 30, 47, 50, and 50, respectively. The change points for total distance, acceleration, maximum speed, deceleration, and high-speed running were located on days 32, 34, 37, 41, and 41, respectively. The multivariate analysis resulted in a single change point for the wellness metrics and running-performance metrics, on days 50 and 67, respectively. Conclusions: The univariate approach provided information regarding the sequence and time point of the change points. The multivariate approach provided a common change point for multiple metrics, information that would benefit clinicians to have a broad overview of the changes in the rehabilitation process. Clinicians may consider the change-point method to integrate and visualize data from multiple sources to evaluate athletes' progression along the return-to-sport continuum. [ABSTRACT FROM AUTHOR]

Purpose: To examine associations between exercise heart rate (HRex) during a continuous-fixed submaximal fitness test (CF-SMFT) and an intermittent-variable protocol (semistandardized kicking drill [SSD]) in Australian Football athletes, controlling for external intensities, within-session scheduling, and environmental conditions. Methods: Forty-four professional male Australian Football athletes (22.8 [8.0] y) were monitored over 10 sessions involving a 3-minute CF-SMFT (12 km·h−1) as the first activity and a SSD administered 35.7 (8.0) minutes after the CF-SMFT. Initial heart rate and HRex were collected, with external intensities measured as average velocity (in meters per minute) and average acceleration–deceleration (in meters per second squared). Environmental conditions were sampled. A penalized hierarchical linear mixed model was tuned for a Bayesian information criterion minima using a 10-fold cross-validation, with out-of-sample prediction accuracy assessed via root-mean-squared error. Results: SSD average acceleration–deceleration, initial heart rate, temperature, and ground hardness were significant moderators in the tuned model. When model covariates were held constant, a 1%-point change in SSD HRex associated with a 0.4%-point change in CF-SMFT HRex (95% CI, 0.3–0.5). The tuned model predicted CF-SMFT HRex with an average root-mean-squared error of 2.64 (0.57) over the 10-fold cross-validation, with 74% and 86% of out-of-sample predictions falling within 2.7%-points and 3.7%-points, respectively, from observed values, representing the lower and upper limits for detecting meaningful changes in HRex according to the documented typical error. Conclusions: Our findings support the use of an SSD to monitor physiological state in Australian Football athletes, despite varied scheduling within session. Model predictions of CF-SMFT HRex from SSD HRex closely aligned with observed values, considering measurement imprecision. [ABSTRACT FROM AUTHOR]

Introduction: In distance running, pacing is characterized by changes in speed, leading to runners dropping off the leader's pace until a few remain to contest victory with a final sprint. Pacing behavior has been well studied over the last 30 years, but much remains unknown. It might be related to finishing position, finishing time, and dependent on critical speed (CS), a surrogate of physiologic capacity. We hypothesized a relationship between CS and the distance at which runners "fell behind" and "let go" from the leader or were "outsprinted" as contributors to performance. Methods: 100-m split times were obtained for athletes in the men's 10,000-m at the 2008 Olympics (N = 35). Split times were individually compared with the winner at the point of "falling behind" (successive split times progressively slower than the winner), "letting go" (large increase in time for distance compared with winner), or "outsprinted" (falling behind despite active acceleration) despite being with the leader with 400 m remaining. Results: Race times ranged between 26:55 and 29:23 (world record = 26:17). There were 3 groups who fell behind at ∼1000 (n = 11), ∼6000 (n = 16), and ∼9000 m (n = 2); let go at ∼4000 (n = 10), ∼7000 (n = 14), and ∼9500 m (n = 5); or were outkicked (n = 6). There was a moderate correlation between CS and finishing position (r =.82), individual mean pace (r =.79), "fell behind" distance (r =.77), and "let go" distance (r =.79). D′ balance was correlated with performance in the last 400 m (r =.87). Conclusions: Athletes displayed distinct patterns of falling behind and letting go. CS serves as a moderate predictor of performance and final placing. Final placing during the sprint is related to preservation of D′ balance. [ABSTRACT FROM AUTHOR]

Purpose: In this study, we compared the influence of movement specificity during velocity–load jump testing to predict on-ice acceleration performance in elite speed skaters. Methods: Elite long-track speed skaters (N = 27) performed velocity–load testing with 3 external loads during unilateral horizontal jumping, lateral jumping, and bilateral vertical countermovement jumping. For the unilateral tests, external load conditions were set to 10 N, 7.5% and 15% of external load relative to body weight. For the countermovement jumping, load conditions were body weight and 30% and 60% of external load relative to body weight. On-ice performance measures were obtained during maximal 50-m accelerations from a standing start, including maximal skating speed, maximal acceleration capacity, and maximum horizontal power. The 100-m split time from a 500-m race was also obtained. Regularized regression models were used to identify the most important predictors of on-ice acceleration performance. In addition to regularized regression coefficients, Pearson correlation coefficients (r) were calculated for all variables retained by the model to assess interrelationships between single predictors and on-ice performance measures. Results: The countermovement jump with 30% of body mass demonstrated the strongest association with maximal skating speed, maximum horizontal power, and 100-m time (regularized regression coefficient =.16−.49, r =.84−.97, P <.001). Horizontal jump with 15% of body mass was the strongest predictor of maximal acceleration capacity performance (regularized regression coefficient =.08, r =.83, P <.001). Conclusions: The findings of this study suggest that mechanical specificity rather than movement specificity was more relevant for predicting on-ice acceleration performance. [ABSTRACT FROM AUTHOR]

Purpose: Global navigation satellite system device–derived metrics are commonly represented by discrete zones with intensity often measured by standardizing volume to per-minute of activity duration. This approach is sensitive to imprecision in duration measurement and can lead to highly variable outcomes—transforming data from zones to a gradient may overcome this problem. The purpose of this study was to critically evaluate this approach for measuring team-sport activity demands. Methods: Data were collected from 129 first-team and 73 academy matches from a Scottish Premiership football club. Gradients were calculated for velocity, acceleration, and deceleration zones, along with per-minute values for several commonly used metrics. Means and 95% CIs were calculated for playing level, as well as first-team positional groups. Within-subject coefficients of variation were also calculated for match level, position, and individual groups. Results: The gradient approach showed consistency with per-minute metrics when measuring playing level and position groups. With coefficients of variation of 10.8% to 26.9%, the gradients demonstrated lower variability than most per-minute variables, which ranged from 10.7% to 84.5%. Conclusions: Gradients are a potentially useful way of describing intensity in team sports and compare favorably to existing intensity variables in their ability to distinguish between match types and position groups, providing evidence that gradient variables can be used to monitor match and training intensity in team sports. [ABSTRACT FROM AUTHOR]

Purpose: This study assessed the reliability and load–velocity profiles of 3 different landmine-punch-throw variations (seated without trunk rotation, seated with trunk rotation, and standing whole body) with different loads (20, 22.5, and 25.0 kg), all with the dominant hand and nondominant hand. Methods: In a quasi-randomized order, 14 boxers (24.1 [4.3] y, 72.6 [10.1] kg) performed 3 repetitions of each variation with their dominant hand and their nondominant hand, with maximal effort and 3 minutes of interset rest. Peak velocity was measured via the GymAware Power Tool (Kinetic Performance Technologies). The interclass correlation coefficients and their 95% CIs were used to determine the intrasession reliability of each variation × load × hand combination. Additionally, a 2 (hand) × 3 (variation) repeated-measures analysis of variance assessed the load–velocity profile slope, and a 3 (variation) × 2 (hand) × 3 (load) repeated-measures analysis of variance assessed the peak velocity of each variation. Results: Most variations were highly reliable (intraclass correlation coefficient >.91), with the nondominant hand being as reliable or more reliable than the dominant hand. Very strong linear relationships were observed for the group average for each variation (R2 ≥.96). However, there was no variation × hand interaction for the slope, and there was no main effect for variation or hand. Additionally, there was no interaction for the peak velocity, but there were main effects for variation, hand, and load (P <.01). Conclusion: Each variation was reliable and can be used to create upper-body ballistic unilateral load–velocity profiles. However, as with other research on load–velocity profile, individual data allowed for more accurate profiling than group average data. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of a newly developed hand rim in wheelchair tennis players from a lab and field perspective. Methods: Nine wheelchair tennis players performed a set of field and lab tests with the new rim (NR) and regular rim on the racket side. Each player had a 60- to 120-minute regular training session with the NR. Three wheelchair tennis field tests (20-m sprint, Illinois, spider) were completed on a hard court using inertial measurement units. The inertial measurement units enabled analysis of linear/rotational velocity and acceleration. In the lab, two 4-minute submaximal tests (at 1.5 and 2 m/s, 0.2 W/kg), followed directly by a 5-second sprint, on a wheelchair ergometer were completed. Force and velocity were measured continuously throughout all tests. Mixed linear models investigated the effect between the 2 hand rims. Results: During the spider test, mean rotational velocity to the racket side (−2%, P =.005) was lower in the NR, and end times were similar between hand-rim conditions. No differences were observed in the 20-m sprint and Illinois field tests. In the lab, contact angle (+6%, P =.04), cycle time (+12%, P =.007), and work per push (+13%, P =.005) were higher in the NR during submaximal propulsion. Work per push (+13%, P =.007), peak velocity (+3%, P <.001), and distance covered (+4%, P =.02) were higher with the NR during the 5-second sprint test. Conclusions: The NR seems slightly favorable compared with the regular rim during performance testing on a wheelchair ergometer in wheelchair tennis players. A longer practice time might show more insights between the hand-rim types. [ABSTRACT FROM AUTHOR]

Purpose: We investigated the effects of manipulating running velocity and hypoxic exposure on vastus lateralis muscle oxygenation levels during treadmill running. Methods: Eleven trained male distance runners performed 7 randomized runs at different velocities (8, 10, 12, 14, 16, 18, and 20 km·h−1), each lasting 45 seconds on an instrumented treadmill in normoxia (fraction of inspired oxygen [FiO2] = 20.9%), moderate hypoxia (FiO2 = 16.1%), high hypoxia (FiO2 = 14.1%), and severe hypoxia (FiO2 = 13.0%). Continuous assessment of Tissue Saturation Index (TSI) in the vastus lateralis muscle was conducted using near-infrared spectroscopy. Subsequently, changes in TSI (ΔTSI) data over the final 20 seconds of each run were compared between velocities and conditions. Results: There was a significant velocity × condition interaction for ΔTSI% (P <.001, η p 2 =.19), with a smaller ΔTSI% decline in normoxia compared with high hypoxia and severe hypoxia at 8 km·h−1 (g = 1.30 and 1.91, respectively), 10 km·h−1 (g = 0.75 and 1.43, respectively), and 12 km·h−1 (g = 1.47 and 1.95, respectively) (pooled values for all conditions: P <.037). The ΔTSI% decline increased with each subsequent velocity increment from 8 km·h−1 (−9.2% [3.7%]) to 20 km·h−1 (−22.5% [4.1%]) irrespective of hypoxia severity (pooled values for all conditions: P <.048). Conclusions: Running at slower velocities in conjunction with high and severe hypoxia reduces vastus lateralis muscle oxygenation levels. Muscle ΔTSI% proves to be a sensitive indicator, underscoring the potential use of near-infrared spectroscopy as a reference index of internal load during treadmill runs. [ABSTRACT FROM AUTHOR]

Background: The benefits of oral caffeine intake to enhance several aspects of physical performance, such as aerobic endurance, strength, power, and muscle endurance performance, are well supported. However, how the physical performance benefits of caffeine supplementation are translated into better specific actions in intermittent sports during real or simulated competition has been the topic of fewer investigations, and their results need to be appropriately reviewed and meta-analyzed. Objective: The aim of the study was to investigate the effects of acute caffeine intake on specific actions in intermittent sports involving decision making and high-intensity efforts (eg, team, racket, and combat sports) during real or simulated competitions. Methods: All studies included had blinded and crossover experimental designs, and we conducted a risk-of-bias analysis. In total, we included 24 studies. A meta-analysis was performed using the random-effects model to calculate the standardized mean difference (SMD) estimated by Hedges g and 95% CIs. Results: Caffeine ingestion increased high-intensity sport-specific actions during competition, such as the number of sprints (SMD: 0.48; 95% CI, 0.23–0.74), body impacts (SMD: 0.28; 95% CI, 0.08–0.49), accelerations (SMD: 0.35; 95% CI, 0.06–0.63), decelerations (SMD: 0.63; 95% CI, 0.12–1.14), and high-intensity offensive efforts (SMD: 0.36; 95% CI, 0.11–0.61). Additionally, caffeine ingestion induced a higher positive or success rate of actions during real or simulated competition (SMD: 0.44; 95% CI, 0.19–0.69). Conclusion: The current meta-analysis provides evidence of caffeine supplementation in increasing high-intensity efforts and the success rate of sport-specific actions during real or simulated competition. [ABSTRACT FROM AUTHOR]

Purpose: Postactivation performance enhancement (PAPE), which refers to the phenomena associated with the attainment of enhanced performance in sport-specific tasks after a conditioning activity, is an important objective of warming-up practices in many sports. This is even more relevant for sprinters, as potential increases in sprinting speed will directly influence their competitive results. This systematic review with meta-analysis evaluated the effects of different PAPE protocols (ie, using plyometrics, strength-power exercises, and resisted/assisted sprints) on the sprinting performance (ie, sprint time or sprint speed) of competitive sprinters. Methods: Initially, 1205 records published until last December 18 were identified, using the following databases: PubMed/MEDLINE, Scopus, and Clarivate Web of Science. After removing duplicates and screening titles and abstracts, 14 high-quality studies met the inclusion criteria for the meta-analysis. Results: Overall, there were no significant changes in sprint performance after implementing various types of conditioning activities (standardized mean difference [SMD] = 0.16 [95% CI, −0.02 to 0.33]; Z = 1.78; P =.08; I2 = 0%). In addition, when comparing prechanges and postchanges between experimental, control, and other conditions, no significant differences were found in sprint speed or time across all studies (SMD = 0.09 [95% CI, −0.10 to 0.28]; Z = 0.92; P =.36; I = 0%). Conclusions: Results revealed that different types of conditioning activities may not be capable of acutely enhancing the sprint speed of competitive sprinters. This aligns with previous observations indicating that sprinting is a highly stable physical capacity, a phenomenon that is even more consistent among elite sprinters. Coaches and sport scientists should collaborate to develop more efficient PAPE protocols for these highly specialized athletes, with special attention to study design and individualization, while considering their effects on acceleration versus top speed. [ABSTRACT FROM AUTHOR]

Purpose: This scoping review aims to identify the primary racket and arm-mounted technologies based on inertial measurement units that enable the quantification of hitting load in racket sports. Methods: A comprehensive search of several databases (PubMed, SPORTDiscus, Web of Science, and IEEE Xplore) and Google search engines was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) extension for scoping reviews guidelines. Included records primarily focused on monitoring hitting load in racket sports using commercialized racket or arm-mounted inertial sensors through noncompetitive and competitive racket-sports players. Results: A total of 484 records were identified, and 19 finally met the inclusion criteria. The largest number of systems found were compatible with tennis (n = 11), followed by badminton (n = 4), table tennis (n = 2), padel (n = 1), and squash (n = 1). Four sensor locations were identified: grip-attached (n = 8), grip-embedded (n = 6), wrist (n = 3), and dampener sensors (n = 2). Among the tennis sensors, only 4 out of the 11 (36.4%) demonstrated excellent reliability (>.85) in monitoring the number of shots hit either during analytic drills or during simulated matches. None of the other racket-sports sensors have undergone successful, reliable validation for hitting-volume quantification. Conclusions: Despite recent advancements in this field, the quantification of hitting volume in racket sports remains a challenge, with only a limited number of tennis devices demonstrating reliable results. Thus, further progress in technology and research is essential to develop comprehensive solutions that adequately address these specific requirements. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed at evaluating the effect of level of competition and drill typology on loads during the preseason period in male volleyball players. Methods: Internal (percentage of peak heart rate [HR] and summated HR zone) and external (PlayerLoad per minute, total and high accelerations per minute [tACCmin and hACCmin], decelerations per minute [tDECmin and hDECmin], and jumps per minute [tJUMPmin and hJUMPmin]) loads were monitored across a 5-week preseason period in 12 Division 1 (age: 22.5 [3.9] y; stature: 188 [6.2] cm; body mass: 85 [11.6] kg; training experience: 9.4 [4.2] y) and 12 Division 2 (age: 20.7 [2.9] y; stature: 186 [6.2] cm; body mass: 77.8 [9.6] kg; training experience: 5.6 [2.3] y) male volleyball players. Furthermore, differences in load were assessed for each drill typology (warm-up, conditioning, technical, tactical, and integral). Results: No effects (P >.05) of level of competition on the internal (except for summated HR zone, P =.05) and external loads (except for tJUMPmin, P =.002) were found. Differently, drill typologies showed an effect (P <.001) on all the investigated internal- and external-load measures. The main post hoc results revealed higher (P <.05) percentage of peak HR, summated HR zone, PlayerLoad per minute, and tACCmin in warm-up and conditioning drills, while higher (P <.05) hDECmin and hJUMPmin were found in tactical and integral drills. Conclusions: These results suggest that volleyball coaches use warm-up and conditioning drills when aiming at increasing the internal loads, PlayerLoad per minute, and tACCmin, while tactical and integral drills should be preferred to enhance the number of hDECmin and hJUMPmin. [ABSTRACT FROM AUTHOR]

Purpose: To characterize and compare female ice hockey players' peak skating speed and acceleration ability during linear sprints and gameplay. We also sought to quantify the time spent at various speeds and the frequency of accelerations at different thresholds during games. Methods: Seventeen varsity-level female ice hockey players (20 [1.4] y, 68.9 [4.9] kg, 167.6 [4.7] cm) participated in an on-ice practice session (performing 3 × 40-m linear sprints) and 4 regular-season games while being monitored using a local positioning system. Speed and acceleration were recorded from the sprint and within-game monitoring. Time on ice spent in relative skating speed zones and the frequency of accelerations at different intensities were recorded. Results: Players' greatest peak speeds (29.5 [1.3] vs 28.3 [1.1] km/h) and accelerations (4.39 [0.48] vs 3.34 [0.36] m/s2) reached during gameplay were higher than those reached in linear sprinting (both P <.01). Peak in-game values were moderately predicted by linear sprint values for speed (r =.69, P <.01) but not for acceleration (r <.01, P =.95). Players spent little time at near-peak linear sprint speeds (≥80% [22.7 km/h], ∼3% time on ice; ≥90% [25.5 km/h], <1% of time on ice) during gameplay. However, 26% to 35% of accelerations recorded during the 4 games were ≥90% of linear sprint acceleration. Conclusions: Although skating speed may be advantageous in specific game situations, our results suggest that players spend little time at near-maximal speeds while accelerating frequently during games. This warrants further investigation of direction changes, skating transitions, repeated sprints, and other determinant variables potentially related to on-ice success and the implementation of training strategies to improve repeated acceleration or qualities beyond maximal skating speed. [ABSTRACT FROM AUTHOR]

Purpose: Power output is dependent on the load used during exercise such as bench-press throw (BPT). Attentional focus (external [EXT] vs internal [INT]) during exercise significantly modulates power performance. The purpose of the present study was to examine the effects of load and attentional focus on mechanical parameters during BPT. Methods: In a crossover study, 31 resistance-trained men (mean age 23.5 [3.0] y) performed BPT at 30% (light), 50% (moderate), and 70% (heavy) of 1-repetition maximum (1-RM) using an INT or EXT focus of attention in randomized order. A linear encoder was used to identify barbell vertical displacement, throw time, peak/average velocity, force, and power during the concentric lifting phase. Results: Statistical analysis revealed significant load × focus interaction effects for velocity and vertical displacement (P ≤.045; 0.66 ≤ d ≤ 0.89). Post hoc analyses indicated significantly larger velocities and displacements at 30% and 70% of 1-RM in favor of EXT (P ≤.038; 0.79 ≤ d ≤ 1.13) but similar values at 50% of 1-RM (P >.05). Furthermore, significant main effects of load were found for throw time, force, and power (P <.001; 4.20 ≤ d ≤ 14.0). While time and force gradually increased with higher loads (P <.001; 1.45 ≤ d ≤ 14.0), power output was larger at 50% compared with 30% and 70% 1-RM (P <.001; 3.09 ≤ d ≤ 7.07), irrespective of attentional focus. Conclusions: The present findings indicated that practitioners may use EXT over INT attentional focus to enhance velocity and vertical displacement during BPT at light and heavy loads (ie, 30% and 70% 1-RM). At moderate loads (ie, 50% 1-RM), mechanical bench-press parameters appear to be less affected by attentional focus. [ABSTRACT FROM AUTHOR]

Purpose: Although running traditionally relies on critical speed (CS) as an indicator of critical intensity, portable inertial measurement units offer a potential solution for estimating running mechanical power to assess critical power (CP) in runners. The purpose of this study was to determine whether CS and CP differ when assessed using the Stryd device, a portable inertial measurement unit, and if 2 running bouts are sufficient to determine CS and CP. Methods: On an outdoor running track, 10 trained runners ( V ˙ O 2 max , 59.0 [4.2] mL·kg−1·min−1) performed 3 running time trials (TT) between 1200 and 4400 m on separate days. CS and CP were derived from 2-parameter hyperbolic speed–time and power–time models, respectively, using 2 (CS2TT and CP2TT) and 3 (CS3TT and CP3TT) TTs. Subsequently, runners performed constant-intensity running for 800 m at their calculated CS3TT and CP3TT. Results: Running at the calculated CS3TT speed (3.88 [0.44] m·s−1) elicited an average Stryd running power (271 [28] W) not different from the calculated CP3TT (270 [28]; P =.940; d = 0.02), with excellent agreement between the 2 values (intraclass correlation coefficient =.980). The CS2TT (3.97 [0.42] m·s−1) was not higher than CS3TT (3.89 [0.44] m·s−1; P =.178; d = 0.46); however, CP2TT (278 [29] W) was greater than CP3TT (P =.041; d = 0.75). Conclusion: The running intensities at CS and CP were similar, supporting the use of running power (Stryd) as a metric of aerobic fitness and exercise prescription, and 2 trials provided a reasonable, albeit higher, estimate of CS and CP. [ABSTRACT FROM AUTHOR]

Purpose: In this commentary, I present arguments against the use of the force–velocity profiling concept in design and adaptations of training programs targeting sprinting. The purpose of this commentary is to make sports practitioners more aware of the rationale behind the concept and explain why it does not work. Rationale: Force–velocity profiling is a mathematical way to present the velocity development during sprint behavior. Some details of this behavior may be accentuated by transforming it to other variables, but it does not add any new information about sprint performance. Thus, contrary to what is often claimed, the force–velocity profile does not represent maximal capacities (ability of force and velocity generation) of the athlete. It is claimed that through force–velocity profiling one may identify the optimal ratio of force and velocity capacities. Furthermore, proponents of the force–velocity profiling concept suggest that through directed training force and velocity capacities can be altered (inversely dependent) to obtain this optimal ratio, without changing the capacity to express power. Fundamentally, this idea is unfounded and implausible. Conclusion: At best, force–velocity profiling may be able to identify between-athletes differences. However, these can be more easily deduced directly from performance time traces. [ABSTRACT FROM AUTHOR]

Purpose: To determine the minimum number of events (training or matches) for producing valid acceleration–speed (AS) profiles from global navigation satellite system (GNSS) data. Methods: Nine elite female soccer players participated in a 4-week training camp consisting of 19 events. AS profile metrics calculated from different combinations of athlete events were compared to force–velocity (FV) profile metrics from 2 × 40-m stand-alone sprint effort trials, using the same GNSS 10-Hz technology. Force–velocity profiles were calculated, from which AS profiles were obtained. AS profiles from training and matches were generated by plotting acceleration and speed points and performing a regression through the maximal points to obtain the AS metrics (theoretical maximal speed, x-intercept [in meters per second], theoretical maximal acceleration, y-intercept [in meters per second squared], and the slope per second). A linear mixed model was performed with the AS metrics as the outcome variables, the number of events as a fixed effect, and the participant identifier as a mixed effect. Dunnett post hoc multiple comparisons were used to compare the means of each number of event grouping (1–19 events) to those estimated from the dedicated sprint test. Results: Theoretical maximal speed and theoretical maximal acceleration means were no longer significantly different from the isolated sprint reference with 9 to 19 (small to trivial differences = −0.31 to −0.04 m·s−1, P =.12–.99) and 6 to 19 (small differences = −0.4 to −0.28 m·s−2, P =.06–.79) events, and the slopes were no longer different with 1 to 19 events (trivial differences = 0.06–0.03 s−1, P =.35–.99). Conclusions: AS profiles can be estimated from a minimum of 9 days of tracking data. Future research should investigate methodology resulting in AS profiles estimated from fewer events. [ABSTRACT FROM AUTHOR]

A correction to the article "Match Running Performance in Australian Football is Related to Muscle Fiber Typology" that was published in the October 10, 2023 online issue is presented.

Previous research has shown that there are differences in mechanical energy, kinematics, and muscle activation when comparing walking on level and incline surfaces, especially on inclines above 15%. Muscle activations are significantly different while walking on extreme inclines, suggesting a different coordination pattern. We utilized continuous relative phase to assess walking kinematic coordination with respect to increased incline angles. Twelve healthy, college-aged individuals walked for 7 inclines of 1 minute each on a motorized treadmill at 3 mph at 0%, 5%, 10%, 15%, 20%, 25%, and 30% inclines. Kinematic data were collected during the last 20 seconds of each stage (120 Hz). Segmental and joint angles and angular velocities in the sagittal plane were calculated, from which continuous relative phase was determined for 3 joint couples: hip–knee, hip–ankle, and knee–ankle. There were significant differences in the coordination patterns during the first part of the contact phase in the hip–knee and hip–ankle couplings between the 0% and 30% inclines, with all 3 joint couplings becoming more in-phase at inclines above 15%. Importantly, the hip–knee coupling changed significantly from more out-of-phase to more in-phase between 10% and 15% incline. Shifting lower-extremity joint coordination in response to extreme inclines identifies potential coordinative strategies to achieve steep walking. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the study was to examine whether various athletic performances, anthropometric measures, and playing experience differentiate selected and nonselected ultimate Frisbee players trialing to compete in the world championship. Methods: Forty-three Australian male ultimate Frisbee players (age = 21.2 [1.2] y; height = 1.7 [6.8] m; body mass = 69.7 [8.2] kg; playing experience = 3.5 [1.5] y) participated in a 30-m sprint test, single-leg run-up jump approach (both left [JumpLL], and right leg [JumpRL]) and a stationary bilateral vertical jump (JumpBIL), and change-of-direction speed test. Following a selection camp, players were subdivided according to their selection or nonselection into the team. Results: A multivariate analysis of variance revealed that height, 10-m sprint time, acceleration, JumpLL, JumpRL, and JumpBIL were significantly greater for selected players than nonselected players (P <.05). Area under the curve (AUC) was greatest for JumpRL (AUC = 79%; optimal cutoff value of 37.5 cm, sensitivity and specificity values of 77% and 71%, respectively), JumpLL (AUC = 74%; optimal cutoff 38.5 cm, sensitivity and specificity values 77% and 77%, respectively), and JumpBIL (AUC = 78%; optimal cutoff value of 40.5 cm, sensitivity and specificity values 71% and 79%, respectively). The largest AUC (AUC = 81%; 95% CI 0.66–0.97; P =.001) was found when combining the explanatory variables that demonstrated moderate to large effect sizes (ie, height, playing experience, 10-m sprint, acceleration, JumpLL, JumpRL, and JumpBIL), with sensitivity of 93% and specificity of 71%. Conclusion: These athletic performance and anthropometric characteristics differentiating selected and nonselected players may help inform targeted training and player-development strategies. [ABSTRACT FROM AUTHOR]

Objectives: To examine the moderating effect of familiarization on the relationship between external load and ratings of perceived exertion (RPEs) in elite youth soccer players. Methods: Thirty-five elite male youth soccer players were monitored over a 31-week period. Players had no previous experience using the centiMax scale (arbitrary units [AU]). The final sample included familiarized (blackness test; n = 20) and nonfamiliarized players (n = 15) with the Borg centiMax scale. Players recorded a global RPE and differential RPEs (dRPE) for breathlessness (RPE-B) and leg-muscle exertion (RPE-L) 15 to 30 minutes following training sessions and competitive matches. Separate multivariable-adjusted random-effects generalized additive models with restricted maximum likelihood quantified familiarization versus no-familiarization differences in actual perceived exertion score (in AU) by number of accelerations, decelerations, and high-speed running distance (in meters) as predictor variables, respectively. Results: Players improved their blackness test score from 39% to 78%. For explorations by number of accelerations, familiarization effects were not practically relevant for the RPE and RPE-B variables. The width and sign of the effects for the RPE-L variable at 30 efforts of 10 AU (95% CI, 4–16 AU) suggested that scores were lower for players who underwent familiarization versus players who did not. Familiarization effects were not practically relevant for any RPE variable irrespective of the number of deceleration efforts and high-speed running distance covered. Conclusion: Improved performance on the blackness test did not have a moderating effect on the relationship between proxy measures of external load and RPEs. [ABSTRACT FROM AUTHOR]

Purpose: To compare the effects between resisted sled sprint training (RSS) and unresisted sprint training (URS) on sprint and acceleration performance, vertical jump, and maximal strength during an 8-week period of preseason training. Methods: Twenty-six recreational active rugby players were randomly divided into either RSS or URS training groups and then performed 8 weeks of training, 2 sessions/wk of sprint-specific training program. The RSS group performed sprints by towing a sled overloaded with 12.6% of body mass for 2 of the 3 sets of 3 × 20-m sprints, plus one set was carried out with unresisted modality. The URS groups performed 3 sets of 3 × 20-m unresisted sprints. The measures of 10- and 30-m sprint times, vertical jump, and 3-repetition-maximum (3-RM) squat tests were performed at baseline and after 8 weeks. Results: Ten- and 30-m sprint times (P <.05 and η p 2 >.44) improved significantly more in RSS than in URS. Both groups improved significantly in vertical jump and 3-RM squat tests; however, no significant differences (P >.1 and η p 2 <.11) between groups were found. Conclusions: Our findings indicate that an 8-week program of RSS is more effective than URS for enhancing sprint time performance in male recreational active rugby players. In addition, these data suggest that a sled overload corresponding to 12.6% of body mass can induce positive effects on both acceleration and speed performance in recreational active rugby players. [ABSTRACT FROM AUTHOR]

Purpose: Variable-speed control in the field is challenging for motion science. Tests were performed to evaluate speed, Froude number, and oxygen consumption if these varied when using the same frequency of steps. The objective of this study was to evaluate the use of auditory feedback to control variable speed on the treadmill and track during acceleration cycles around the transition speed. Methods: Twenty-four trained men participated. The protocol was based on 5 ramps of 50 seconds each around 80%, 90%, 100%, 110%, and 120% of the walking–running transition speed, recording the frequency of steps with a mobile phone during the treadmill test. The tests were replicated on the track using auditory feedback. Results: When evaluating each speed of the protocols separately for the same frequency of steps, the average speed on the track was always higher on average at 54.7% compared to the laboratory (P <.050), and on the track, it was 16.2% higher than in the laboratory (P >.050). Conclusions: It cannot be considered that the same frequency of steps is equivalent to the same speed in the laboratory and on the track. These results point to the importance of reliable speed control during open field tests. [ABSTRACT FROM AUTHOR]

Context: Different resistance exercise determinants modulate the musculotendinous adaptations following eccentric hamstring training. The Nordic Hamstring Exercise (NHE) can be performed 2-fold: the movement velocity irreversibly increases toward the end of the range of motion or it is kept constant. Design: This cross-sectional study aimed to investigate if the downward acceleration angle (DWAangle) can be used as a classification parameter to distinguish between increasing and constant velocity NHE execution. Furthermore, the kinetic and kinematic differences of these 2 NHE execution conditions were examined by analyzing the DWAangle in relation to the angle of peak moment. Methods: A total of 613 unassisted NHE repetitions of 12 trained male sprinters (22 y, 181 cm, 76 kg) were analyzed. Results: The majority of analyzed parameters demonstrated large effects. NHEs with constant velocity (n = 285) revealed significantly higher impulses (P <.001; d = 2.34; + 61%) and fractional time under tension (P <.001; d = 1.29; +143%). Although the generated peak moments were significantly higher for constant velocity (P =.003; d = 0.29; +4%), they emerged at similar knee flexion angles (P =.167; d = 0.28) and revealed on average just low relationships to the DWAangle ( R mean 2 = 22.4 %). DWAangle highly correlated with the impulse ( R mean 2 = 60.8 %) and δ (DWAangle–angle of peak moment; R mean 2 = 83.6 %). Conclusions: Relating DWAangle to angle of peak moment assists to distinguish between significantly different NHE execution, which will potentially elicit different musculotendinous adaptations. These insights are essential for coaches and athletes to understand how to manipulate eccentric hamstring training to change its purpose. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the relationships between a series of direct and indirect measures of linear and multidirectional speed performance in elite female rugby sevens players. Methods: Nineteen players from the Brazilian national team performed 40-m linear sprint and 505 change-of-direction (COD) tests on the same day. Based on the linear sprint and COD test performances, the COD deficit (CODD) and deceleration deficit (DD) were also obtained. A Pearson product–moment correlation analysis was used to determine the relationships between linear sprint and COD-derived variables. Results: Linear sprint and 505 COD velocities were not significantly associated (P >.05). Large to very large significant associations (r values ranging from.54 to.78; P <.05) were detected between linear sprint velocity for the different distances tested (10, 15, 30, and 40 m) and CODD. The COD velocity presented a very large inverse significant correlation with CODD and DD (r = −.77 and −.79 respectively; P <.05). A large and significant correlation was identified between CODD and DD (r =.79; P <.05). Conclusions: Significant associations were observed between linear sprint and CODD, suggesting that faster players are less efficient at changing direction. No relationship was found between sprint velocity and DD, highlighting the independent nature of linear sprints and deceleration capabilities. A comprehensive and detailed analysis of multidirectional speed performance should consider not only linear sprint and COD performances but also complementary COD-derived variables such as the CODD and DD. [ABSTRACT FROM AUTHOR]

Purpose: This study sought to quantify the within-individual relationships between spatiotemporal variables and initial acceleration sprint performance in elite rugby backs and to establish a normative data set of relevant strength-based measures. Methods: First, the spatiotemporal variables, ratios of step length to step rate and of contact time to flight time, and initial acceleration performance were obtained from 35 elite male rugby backs (mean [SD] age 25 [3] y) over the first 4 steps of 3 sprints. Angular and linear kinematic aspects of technique and strength-based qualities were collected from 25 of these participants. Second, the same spatiotemporal variables were collected from 19 of the participants on 3 further occasions (12 trials in total) to determine the within-individual associations of these variables and initial acceleration performance. Results: Moderate to very large meaningful within-individual relationships (|r| =.43–.88) were found between spatiotemporal variables and initial acceleration performance in 17 of the 19 participants. From these relationships, a theoretically "desirable" change in whole-body kinematic strategy was individually determined for each participant, and normative strength-based measures to contextualize these were established. Conclusions: Meaningful within-individual relationships are evident between sprint spatiotemporal variables and initial acceleration performance in elite rugby backs. Individualized approaches are therefore necessary to understand how aspects of technique relate to initial acceleration performance. This study provides an objective, evidence-based approach for applied practitioners to identify the initial acceleration technical needs of individual rugby backs. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the indirect measurement of 1-repetition-maximum (1RM) free-weight half-squat in high-level sprinters using the load–velocity relationship. Methods: Half-squat load and velocity data from 11 elite sprinters were collected in 2 separate testing sessions. Approximately 24 hours prior to the first testing session, sprinters completed a fatiguing high-intensity training session consisting of running intervals, staircase exercises, and body-weight exercises. Prior to the second testing session, sprinters had rested at least 48 hours. Two different prediction models (multiple-point method, 2-point method) were used to estimate 1RM based on the load and either mean or peak concentric velocity data of submaximal lifts (40%–90% 1RM). The criterion validity of all methods was examined through intraclass correlation coefficients, coefficient of variation (CV%), Bland–Altman plots, and the SEM. Results: None of the estimations were significantly different from the actual 1RM. The multiple-point method showed higher intraclass correlation coefficients (.91 to.97), with CVs from 3.6% to 11.7% and SEMs from 5.4% to 10.6%. The 2-point method showed slightly lower intraclass correlation coefficients (.76 to.95), with CVs 1.4% to 17.5% and SEMs from 9.8% to 26.1%. Bland–Altman plots revealed a mean random bias in estimation of 1RM for both methods (mean and peak velocity) ranging from 1.06 to 13.79 kg. Conclusion: Velocity-based methods can be used to roughly estimate 1RM in elite sprinters in the rested and fatigued conditions. However, all methods showed variations that limit their applicability for accurate load prescription for individual athletes. [ABSTRACT FROM AUTHOR]

Background: Sprinting is important for both individual and team sports, and enhancing performance is often done through resisted, assisted, or combined sprint training. However, the effectiveness of these methods compared to traditional sprint training remains inconclusive. The objective of this review with meta-analysis was to review the current literature on intervention studies analyzing the effects of resisted, assisted, and combined (resisted–assisted) training on sprint kinematics and performance in terms of acceleration and maximum velocity. Methods: A literature search was conducted using SPORTDiscus up to and including April 19, 2023. The following eligibility criteria were applied: (1) a longitudinal study over a minimum of four weeks; (2) studies using resistance (sleds, parachutes, uphill slope, towing devices) or assistance (towing devices, downhill slope), or a combination of both; (3) a main intervention focused on resisted or assisted training, or a combination of both; (4) measurement of maximum velocity, acceleration measured in (s) with a minimum distance of 10-m, or kinematic changes such as step frequency, ground contact time, flight time, and step length; and (5) peer-reviewed studies. Results: Twenty-one studies were included in this review with meta-analysis. Kinematic changes, changes in acceleration, and changes in maximum velocity were analyzed. Only resisted sprint training was associated with a significant improvement in 10-m acceleration compared to normal (i.e. without assistance or resistance) sprinting (Z = 2.01, P = 0.04). With resisted, assisted and combined sprint training no significant changes in kinematics, 20-m times or maximum velocity were found when compared to normal sprint training. However, in the within group, effect sizes resisted sprint training had a moderate effect on 10-m times. A moderate effect on ground contact time, step frequency, 10-and 20-meter time after assisted sprint training was found, while combined sprint training had a moderate effect on maximum velocity. Conclusion: Resisted sprint training seems to be effective for improving acceleration ability, with significant decreases in the 10-m times. There were no other significant findings, suggesting that normal sprinting yields the same change in 20-m times, kinematics and maximum velocity as resisted, assisted and combined sprint training. However, moderate effect sizes using these different training methods were found, which may suggest that the different training forms could be useful for improving different parts of the sprint and changing the kinematics. Combination (uphill–downhill) sprint training seems to be effective at improving maximum velocity, while assisted sprint training was the most effective training to increase step frequency, which can affect sprint performance positively. However, more studies, especially in assisted sprints, need to be conducted to determine the full effect of these training forms. Key Points: • Resisted sprint training is effective for improving acceleration ability; however, combination (uphill–downhill) sprint training is more effective at improving maximum velocity. • The overall group analysis shows that all of the training forms decrease the flight time. • Assisted sprint training is the most effective training to increase step frequency, which can affect sprint performance positively. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the difference in head acceleration event (HAE) incidence between training and match‐play in women's and men's players competing at the highest level of domestic rugby union globally. Players from Women's (Premiership Women's Rugby, Farah Palmer Cup) and Men's (Premiership Rugby, Currie Cup) rugby union competitions wore instrumented mouthguards during matches and training sessions during the 2022/2023 seasons. Peak linear (PLA) and angular (PAA) acceleration were calculated from each HAE and included within generalized linear mixed‐effects models. The incidence of HAEs was significantly greater in match‐play compared to training for all magnitude thresholds in both forwards and backs, despite players spending approximately 1.75–2.5 times more time in training. For all HAEs (PLA > 5 g and PAA > 400 rad/s2), incidence rate ratios (IRRs) for match versus training ranged from 2.80 (95% CI: 2.38–3.30; men's forwards) to 4.00 (3.31–4.84; women's forwards). At higher magnitude thresholds (PLA > 25 g; PAA > 2000 rad/s2), IRRs ranged from 3.64 (2.02–6.55; PAA > 2000 rad/s2 in men's backs) to 11.70 (6.50–21.08; PAA > 2000 rad/s2 in women's forwards). Similar trends were observed in each competition. Players experienced significantly more HAEs during match‐play than training, particularly at higher magnitude thresholds. Where feasible, HAE mitigation strategies may have more scope for HAE reduction if targeted at match‐play, particularly where higher magnitude HAEs are the primary concern. However, the number of HAEs associated with different training drills requires exploration to understand if HAEs can be reduced in training, alongside optimizing match performance (e.g., enhancing contact technique). [ABSTRACT FROM AUTHOR]

This study examined the effects of menstrual cycle phases and symptoms on match running performance in football (soccer) players. Twenty‐one nonhormonal contraceptive using football players from four professional teams were monitored for up to four menstrual cycles during a domestic league season. Menstrual phases, classified as early‐follicular phase (EFP), mid‐late follicular phase (MFP), and luteal phase (LP), were determined by self‐reporting of menstruation and urinary hormone tests (luteinizing hormone and pregnanediol‐3‐glucuronide). On match day, players completed a menstrual symptom severity questionnaire. In repeated matches, players wore 10 Hz Global Positioning Satellite (GPS) devices to measure relative (/min) total distance, high‐speed running distance, very high‐speed distance, peak speed, acceleration count, and deceleration count. Linear mixed models were performed for each GPS measure to determine the relationship with phase or symptoms. Data for 7 and 10 players were included for menstrual phase and menstrual symptoms analyses, respectively. A significantly higher total distance was reported during MFP compared to EFP (Δ 5.1 m min−1; p = 0.04) and LP (Δ 5.8 m min−1; p = 0.007). Significantly greater high‐speed running was reported during MFP compared to EFP (Δ 1.2 m min−1; p = 0.012) and LP (Δ 1.1 m min−1; p = 0.007). No significant effect of menstrual phase was found for any other GPS measures (p > 0.05). Accelerations declined with increasing symptom severity (p = 0.021, estimate = −0.01count.min−1). Menstrual symptom severity did not affect any other GPS measures (p > 0.05). In conclusion, greater total distance and high‐speed running occurred during the MFP. Additionally, accelerations minimally decreased with increasing menstrual symptom severity. Large intra‐ and inter‐variability existed, suggesting individualized monitoring and management of menstrual effects on performance would be beneficial. [ABSTRACT FROM AUTHOR]

Objectives: To describe and compare the incidence and propensity of head acceleration events (HAEs) using instrumented mouthguards (iMG) by playing position in a season of English elite-level men's and women's rugby union matches. Methods: iMG data were collected for 255 men and 133 women from 1,865 and 807 player-matches, respectively, and synchronised to video-coded match footage. Head peak resultant linear acceleration (PLA) and peak resultant angular acceleration (PAA) were extracted from each HAE. Mean incidence and propensity values were calculated across different recording thresholds for forwards and backs in addition to positional groups (front row, second row, back row, half backs, centres, back three) with 95% confidence intervals (CI) estimated. Significance was determined based on 95% CI not overlapping across recording thresholds. Results: For both men and women, HAE incidence was twice as high for forwards than backs across the majority of recording thresholds. HAE incidence and propensity were significantly lower in the women's game compared to the men's game. Back-row and front-row players had the highest incidence across all HAE thresholds for men's forwards, while women's forward positional groups and men's and women's back positional groups were similar. Tackles and carries exhibited a greater propensity to result in HAE for forward positional groups and the back three in the men's game, and back row in the women's game. Conclusion: These data offer valuable benchmark and comparative data for future research, HAE mitigation strategies, and management of HAE exposure in elite rugby players. Positional-specific differences in HAE incidence and propensity should be considered in future mitigation strategies. [ABSTRACT FROM AUTHOR]

Background: Despite widespread use of intensity zones to quantify external load variables in basketball research, the consistency in identifying zones and accompanying intensity thresholds using predominant monitoring approaches in training and games remains unclear. Objectives: The purpose of this work was to examine the external load intensity zones and thresholds adopted across basketball studies using video-based time-motion analysis (TMA), microsensors, and local positioning systems (LPS). Methods: PubMed, MEDLINE, and SPORTDiscus databases were searched from inception until 31 January 2023 for studies using intensity zones to quantify external load during basketball training sessions or games. Studies were excluded if they examined players participating in recreational or wheelchair basketball, were reviews or meta-analyses, or utilized monitoring approaches other than video-based TMA, microsensors, or LPS. Results: Following screening, 86 studies were included. Video-based TMA studies consistently classified jogging, running, sprinting, and jumping as intensity zones, but demonstrated considerable variation in classifying low-intensity (standing and walking) and basketball-specific activities. Microsensor studies mostly utilized a single, and rather consistent, threshold to identify only high-intensity activities (> 3.5 m·s−2 for accelerations, decelerations, and changes-in-direction or > 40 cm for jumps), not separately quantifying lower intensity zones. Similarly, LPS studies predominantly quantified only high-intensity activities in a relatively consistent manner for speed (> 18.0 m·s−1) and acceleration/deceleration zones (> 2.0 m·s−2); however, the thresholds adopted for various intensity zones differed greatly to those used in TMA and microsensor research. Conclusions: Notable inconsistencies were mostly evident for low-intensity activities, basketball-specific activities, and between the different monitoring approaches. Accordingly, we recommend further research to inform the development of consensus guidelines outlining suitable approaches when setting external load intensity zones and accompanying thresholds in research and practice. [ABSTRACT FROM AUTHOR]

Background and Objective: Understanding and recognizing basketball offensive set plays, which involve intricate interactions between players, have always been regarded as challenging tasks for untrained humans, not to mention machines. In this study, our objective is to propose an artificial intelligence model that can automatically recognize offensive plays using a novel self-supervised learning approach. Methods: The dataset was collected by SportVU from 632 games during the 2015–2016 season of the National Basketball Association (NBA), with a total of 90,524 possessions. A multi-agent motion prediction pretraining model was built on the basis of axial-attention transformer and trained with different masking strategies: motion prediction (MP), motion reconstruction (MR), and MP + MR joint strategy. A downstream play-level classification task and similarity search were used to evaluate the models' performance. Results: The results showed that the MP + MR joint masking strategy maximized the ability of the model compared with individual masking strategies. For the classification task, the joint strategy achieved a top-1 accuracy of 81.5% and top-3 accuracy of 97.5%. In the similarity search evaluation, the joint strategy attained a top-5 accuracy of 76% and top-10 accuracy of 59%. Additionally, with the same MP + MR joint masking strategy, our HoopTransformer model outperformed the two baseline models in the classification task and similarity search. Conclusion: This study presents a self-supervised learning model and demonstrates the effectiveness and potential of the model in accurately comprehending and capturing player movements and complex interactions during offensive plays. [ABSTRACT FROM AUTHOR]

Athletes use either an eight-step or a seven-step strategy to reach the first hurdle in the 110 m hurdles event. This study investigates the effect of step strategy on the hurdle clearance technique and spatio-temporal parameters of the four steps prior to hurdle clearance. Two-dimensional video data were collected in the sagittal plane from 12 male sprinters, grouped as seven-step (n = 6) or eight-step (n = 6) strategists. The take-off distance was 0.20 m further from the hurdle and the touchdown was 0.42 m closer to the hurdle for seven-step athletes. Additionally, seven-step athletes reduced the length of the final step before hurdle take-off by 0.14 m compared with the previous step, whereas the eight-step athletes extended their final step by 0.17 m. There was negligible difference between the mean horizontal velocities of the two groups throughout the hurdle clearance (0.02 m/s) or the approach time to the first hurdle from the block clearance (0.01 s). This presents an important first insight into the effect of the step strategy on the first hurdle kinematics. Our findings identify the take-off and touchdown distance parameters of the hurdle clearance technique, and approach step characteristics for a successful seven- or eight-step approach strategy to be employed. [ABSTRACT FROM AUTHOR]

In cross-country ski skating, both the G2 and G4 sub-techniques involve one pole push for every second ski push but are used at largely different speed-slope ranges. The aim of this study was to compare temporal and kinematic patterns between G2 and G4 at both identical and different speed-slope conditions. A mixed model was used to analyse spatio-temporal parameters, while a combination of dynamic time warping and statistical parametric mapping was used to compare time traces. Main spatio-temporal parameters, such as cycle time, ski contact time and swing time, differed between G2 and G4 (all p < 0.01). Moreover, two forward and more pronounced acceleration phases of the centre of mass (CoM) were visible in G4 while only one acceleration phase was present in G2. The more continuous propulsion in G2 allows for maintaining a more constant speed at steep slopes and low speeds where this sub-technique is preferred. In contrast, the achievement of high speeds while skiing on flatter terrain seem to require more dynamic motion with shorter, more explosive propulsion periods allowed for in G4. In conclusion, G2 and G4 are two unique movements as characterised by fundamentally different CoM motion and should be denoted as two different sub-techniques. [ABSTRACT FROM AUTHOR]

Sprinting ability is important for successful performance in sports. The aim of this study was to examine the correlation between force-velocity-power relationship of a whole-body movement and sprint performance. Twelve male participants performed maximal squat jumps with additional loads ranging from 0% to 100% body weight to obtain force-velocity profiles. The mean force and velocity were calculated during the push-off phase for each jump, which resulted in a force-velocity curve. The theoretical maximal force (F0), theoretical maximal velocity (V0) and theoretical maximum power (P0) were computed via extrapolation of the force and velocity data. In the second session, participants performed two 60 m sprints and the time to cover 20 m (t20), time to cover 60 m (t60), and maximum sprint velocity (Vmax) were calculated from the best 60 m trial. Correlation analyses revealed strong and significant correlations between V0 and t20 (r = −0.60), V0 and t60 (r = −0.60), P0 and t20 (r = −0.75) and P0 and t60 (r = −0.78). Multiple linear regression indicated that P0 explained 56%, 61% and 60% of the variability in t20, t60 and Vmax, respectively. Our results emphasise the importance of developing power production capabilities to improve sprint performance. [ABSTRACT FROM AUTHOR]

Emotion is an important factor that can lead to the occurrence of aggressive driving. This paper proposes an association rule mining-based method for analysing contributing factors associated with aggressive driving behaviour among online car-hailing drivers. We collected drivers' emotion data in real time in a natural driving setting. The findings show that 29 of the top 50 association rules for aggressive driving are related to emotions, revealing a strong relationship between driver emotions and aggressive driving behaviour. The emotions of anger, surprised, happy and disgusted are frequently associated with aggressive driving behaviour. Negative emotions combined with other factors (for example, driving at high speeds and high acceleration rates and with no passengers in the vehicle) are more likely to lead to aggressive driving behaviour than negative emotions alone. The results of this study provide practical implications for the supervision and training of car-hailing drivers. PRACTITIONER SUMMARY: Based on the association rule mining method, we found a close connection between drivers' emotional states and the manifestation of aggressive driving behaviours. The findings indicate that the combination of negative emotions and various contributing factors significantly amplifies the likelihood of aggressive driving. [ABSTRACT FROM AUTHOR]

Background: Biomechanical parameters can distinguish a skilled rower from a less skilled rower and can provide coaches with meaningful feedback and objective evidence to inform coaching practices on rowing technique. Therefore, it is critical to understand which technical characteristics can be related to the fundamental rowing performance indicators. The aim of this systematic scoping review was to describe the current focus and density of rowing biomechanics research specific to on-water rowing and provide a guide for practitioners and researchers on future directions for on-water rowing biomechanics research. Methods: All peer-reviewed publications involving the on-water assessment of rowing biomechanics were reviewed from four databases (SPORTDiscus, PubMed, Sage online journals, and Web of Science). Search results returned 1659 records, of which 27 studies met the inclusion criteria for the review. Results: All reported variables were collated and summarised according to the three main measurements of basic mechanics: time, space and force. Study characteristics were collated to provide a descriptive overview of the literature. The main categorical variables included time, distance, velocity, acceleration, force, power and crew synchrony. Conclusion: Data extraction revealed gate force, horizontal oar angle and boat velocity as the most reported variables with numerous subcategories of metrics within each measure. A framework to help guide and standardise on-water rowing biomechanical assessment and the establishment of standards for environmental data collection could help guide practitioners and researchers in the on-water rowing environment. This scoping review was registered on the Open Science Framework (https://osf.io/8q5vw/). Key Points: While the literature has reported on an extensive range of biomechanical metrics relevant to rowing performance, however, the variability of reported measures across the different boat classes, sex and skill levels makes the collation of data challenging. The rate at which a rower can apply force and the ability to maintain the force into the finish are distinguishing features of elite rowing while prioritizing the measurement and application of power is essential for effectively monitoring and controlling training loads, as well as for refining technique. The development of a standardized framework for on-water rowing biomechanical assessment, coupled with established protocols for environmental data collection, would provide practitioners and researchers with a structured approach for navigating the on-water rowing context. [ABSTRACT FROM AUTHOR]

The aim was to assess concurrent validity and test–retest reliability of spatiotemporal gait parameters from a thoracic-placed inertial measurement unit (IMU) in lab- (Phase One) and field-based (Phase Two) conditions. Spatiotemporal gait parameters were compared (target speeds 3, 5 and 7.5 m·s−1) between a 100 Hz IMU and an optical measurement system (OptoJump Next, 1000 hz) in 14 trained individuals (Phase One). Additionally, 29 English Premier League football players performed weekly 3 × 60 m runs (5 m·s−1; observations = 1227; Phase Two). Mixed effects modelling assessed the effect of speed on agreement between systems (Phase One) and test–retest reliability (Phase Two). IMU step time showed strong agreement (<0.3%) regardless of individual or running speed. Direction of mean biases up to 40 ms for contact and flight time depended on the running speed and individual. Step time, length and frequency were most reliable (coefficient of variation = 1.3-1.4%) but confounded by running speed. Step time, length and frequency derived from a thoracic-placed IMU can be used confidently. Contact time could be used if bias is corrected for each individual. To optimise test–retest reliability, a minimum running distance of 40 m is needed to ensure 10 constant-speed steps is gathered. [ABSTRACT FROM AUTHOR]

This study compared lower extremity, trunk, and upper extremity kinematics between tee and front toss hitting in youth baseball athletes. Twenty youth baseball athletes (14.3±2.9 yrs) performed three maximal effort swings off front toss and tee. Kinematic data were collected during the preparatory and acceleration phases. Lower extremity, trunk, and upper extremity kinematics were compared between tee and front toss hitting using 1-dimensional statistical parametric mapping (SPM). There was a significant difference in trunk kinematics between tee and front toss during the preparatory phase (p=.001); the trunk rotated more toward the back side when hitting off a tee compared to front toss (p<0.001). There was also a significant difference in trunk kinematics between tee and front toss for 67% of the acceleration phase; the trunk rotated more towards the back side from 0 to 67% when hitting off the tee (p<0.001). Significant differences were found in trunk kinematics between tee and front toss hitting in youth baseball players, where the trunk is less rotated toward the pitcher in the tee than in the front toss. Coaches utilize various training modalities to enhance hitting performance; however, differences in trunk kinematics should be considered between modalities when developing fundamental hitting techiques in youth baseball athletes. [ABSTRACT FROM AUTHOR]

Background: Various studies have shown that the type of intensity measure affects training intensity distribution (TID) computation. These conclusions arise from studies presenting data from meso- and macrocycles, while microcycles, e.g., high-intensity interval training shock microcycles (HIIT-SM) have been neglected so far. Previous literature has suggested that the time spent in the high-intensity zone, i.e., zone 3 (Z3) or the "red zone", during HIIT may be important to achieve improvements in endurance performance parameters. Therefore, this randomized controlled trial aimed to compare the TID based on running velocity (TIDV), running power (TIDP) and heart rate (TIDHR) during a 7-day HIIT-SM. Twenty-nine endurance-trained participant were allocated to a HIIT-SM consisting of 10 HIIT sessions without (HSM, n = 9) or with (HSM + LIT, n = 9) additional low-intensity training or a control group (n = 11). Moreover, we explored relationships between time spent in Z3 determined by running velocity (Z3V), running power (Z3P), heart rate (Z3HR), oxygen uptake ( Z 3 V ˙ O 2 ) and changes in endurance performance. Results: Both intervention groups revealed a polarized pattern for TIDV (HSM: Z1: 38 ± 17, Z2: 16 ± 17, Z3: 46 ± 2%; HSM + LIT: Z1: 59 ± 18, Z2: 14 ± 18, Z3: 27 ± 2%) and TIDP (Z1: 50 ± 8, Z2: 14 ± 11, Z3: 36 ± 7%; Z1: 62 ± 15, Z2: 12 ± 16, Z3: 26 ± 2%), while TIDHR (Z1: 48 ± 13, Z2: 26 ± 11, Z3: 26 ± 7%; Z1: 65 ± 17, Z2: 22 ± 18, Z3: 13 ± 4%) showed a pyramidal pattern. Time in Z3HR was significantly less compared to Z3V and Z3P in both intervention groups (all p < 0.01). There was a time x intensity measure interaction for time in Z3 across the 10 HIIT sessions for HSM + LIT (p < 0.001, pη2 = 0.30). Time in Z3V and Z3P within each single HIIT session remained stable over the training period for both intervention groups. Time in Z3HR declined in HSM from the first (47%) to the last (28%) session, which was more pronounced in HSM + LIT (45% to 16%). A moderate dose–response relationship was found for time in Z3V and changes in peak power output (rs = 0.52, p = 0.028) as well as time trial performance (rs = − 0.47, p = 0.049) with no such associations regarding time in Z3P, Z3HR, and Z 3 V ˙ O 2 . Conclusion: The present study reveals that the type of intensity measure strongly affects TID computation during a HIIT-SM. As heart rate tends to underestimate the intensity during HIIT-SM, heart rate-based training decisions should be made cautiously. In addition, time in Z3V was most closely associated with changes in endurance performance. Thus, for evaluating a HIIT-SM, we suggest integrating a comprehensive set of intensity measures. Trial Registration Trial register: Clinicaltrials.gov, registration number: NCT05067426. Key Points: Using heart rate, running velocity and running power as measures of intensity leads to different patterns of training intensity distribution during a 7-day HIIT shock microcycle. A polarized pattern was observed for velocity and power, whereas a more pyramidal distribution was found for heart rate. Additional low-intensity training volume during a HIIT shock microcycle led to a more pronounced decline in time in zone 3 measured with heart rate compared to a shock microcycle with HIIT sessions, only. A moderate dose–response relationship was observed between time in zone 3 measured by velocity and changes in peak power output as well as time-trial performance. No such correlation was found between time in zone 3 measured by power, heart rate, oxygen uptake, and changes in endurance performance parameters. [ABSTRACT FROM AUTHOR]

This study describes the training demands of highly trained male youth basketball players, based on training year, term and playing position. Data was collected from 41 male youth basketballers over two seasons from all on-court coach-led training sessions utilising an LPS. Linear mixed-models and pairwise comparisons were used to analyse by training year (Y1, Y2 and Y3), term (T1, T2, T3 and T4) and playing position (Backcourt, Frontcourt). Results showed no differences in external load metrics between training years. Significant differences existed between training terms, with total distance greater in both T3 and T4 than T1 and 2 (p < 0.03). Total PlayerLoad was significantly greater in T4 than T1 (p < 0.001) and T3 (p = 0.004). Distance/min was greater in T2, T3 and T4 than T1 (p < 0.01). PlayerLoad/min was higher in T4 than T1 and T2 (p < 0.01). Backcourt players showed significantly greater distance/min (p = 0.011), PlayerLoad/min (p = 0.011) and deceleration counts (p < 0.001). Overall, limited year-on-year change existed in external training load metrics (p > 0.05), though volume (p < 0.001) and intensity (p < 0.001) differed between terms. Backcourt players completed higher intensities (p = 0.011) than Frontcourt players. This study provides a description of external loads of training in highly trained youth basketball players assisting coaches and performance practitioners to better understand physical demands within youth basketball development pathways. [ABSTRACT FROM AUTHOR]

Sports injuries pose significant challenges in athlete welfare and team dynamics, particularly in high-intensity sports like soccer. This study used machine learning algorithms to assess non-contact injury risk in professional male soccer players from physiological and mechanical load variables. Twenty-five professional male soccer players with a first-time, non-contact muscle injury were included in this study. Recordings of external load (speed, distance, and acceleration/deceleration data) and internal load (heart rate) were obtained during all training sessions and official matches over a 4-year period. Machine learning model training and evaluation features were calculated for each of nine different metrics for a 28-day period prior to the injury and an equal-length baseline epoch. The acute surge in the values of each workload metric was quantified by the deviation of maximum values from the average, while the variations of cumulative workload over the last four weeks preceding injury were also calculated. Seven features were selected by the model as prominent estimators of injury incidence. Three of the features concerned acute load deviations (number of sprints, training load score-incorporating heart rate and muscle load- and time of heart rate at the 90 - 100% of maximum). The four cumulative load features were (total distance, high speed and sprint running distance and training load score). The accuracy of the muscle injury risk assessment model was 0.78, with a sensitivity of 0.73 and specificity of 0.85. Our model achieved high performance in injury risk detection using a limited number of training load variables. The inclusion, for the first time, of heart rate related variables in an injury risk assessment model highlights the importance of physiological overload as a contributor to muscle injuries in soccer. By identifying the important parameters, coaches may prevent muscle injuries by controlling surges of training load during training and competition. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the physical and physiological demands of intercounty camogie match-play between positions and halves of play. Data were collected from 28 players during 18 competitive games using global positioning systems (10-Hz) and heart rate monitors (2.4-GHz). The study demonstrated that intercounty camogie players covered a total distance (TD) (m ± SD) of 6,040 ± 628 m, relative distance (RD) of 83 ± 13 m⋅min-1, and maximum speed of 25 ± 1 km⋅h-1. Furthermore, the players covered a mean sprint distance of 214 ± 112 m and 14 ± 6 sprints. Players' mean heart rate (HRmean) and HRmaxwas 138 ± 23 b⋅min-1 and 164 ± 20 b⋅min-1, respectively. There were decrements between halves in TD (p < 0.01, ES = -0.45), RD (p < 0.01, ES = -0.45), maximum speed (p < 0.05, ES 5 -0.18), HRmax(p < 0.05, ES = -0.23), running (p < 0.01, ES = -0.34), high-speed running (p < 0.01, ES = 0.34), sprinting (p < 0.01, ES 5 -0.10), HRmax(p < 0.05, ES = -0.23), and HRmax % (p < 0.05, ES = -0.24). Midfielders covered a greater TD compared with full-forwards (p < 0.05, ES 5 -0.38) and half-forwards (p < 0.05, ES 5 -0.38). Full-backs covered a significantly lower RD than midfielders (p < 0.05, ES 5 -1.2), half-backs compared with full-forwards (p < 0.05, ES 5 1.14), and half-forwards compared with full-forwards (p < 0.05, ES 5 1.15). Full-forwards covered significantly less RD when compared with half-backs (p < 0.05, ES 5 -1.14), midfielders (p < 0.05, ES 5 -1.47), and half-forwards (p < 0.05, ES 5 -1.15). The findings provide physical and physiological values on the match demands of intercounty camogie match-play. [ABSTRACT FROM AUTHOR]

This study investigates the inter-week test-retest reliability of 9.14 meter (10 yard) sprint times in youth athletes. Although essential for assessing athletic ability and training efficacy, the critical and comprehensive examination of both relative and absolute reliability indices for short-distance sprints has been insufficient in youth contexts. One hundred ninety-eight youth athletes (128 males and 70 females) underwent 2 sprint attempts across 2 separate trials 24 hours apart and within 7 days of each other. The sprints were measured using dual-beam timing gates to capture split times for 0-4.57 meter (0-5 yards), 4.57-9.14 meter (5-10 yards), and 0-9.14 meter (0-10 yards). The minimal mean difference between the best sprint times across trials was 0.02 ± 0.13 seconds for males and 0.003 ± 0.14 seconds for females. No significant mean differences were found between trials for either gender (males: p = 0.0875; females: p = 0.8752), suggesting no systematic bias in sprint times. The SEM was 0.092 seconds for males and 0.099 seconds for females, with a corresponding SEMCV% of 4.6 and 4.8%. The overall coefficient of variation was 9.8% for males and 8.9% for females. Intraclass correlation coefficient values suggested that the sprint times across trials were reliable (males: 0.80; females: 0.76). The minimal detectable change was 0.25 seconds for males, 0.27 seconds for females. Cohen's d indicated trivial effects (<0.2) for males (0.154) and females (0.021). Minimal mean differences, a low SEM, and consistent ICC values demonstrate that the 0-9.14 meter sprint is a reliable assessment in youth athletes. [ABSTRACT FROM AUTHOR]