Search

Purpose: To investigate the influence of menstrual-cycle (MC) phase on objective sleep and perceived recovery following high- (HIT) and low-intensity training (LIT) in endurance-trained women. Methods: Fifteen naturally menstruating, endurance-trained women completed standardized HIT and LIT sessions during the early follicular phase (EFP), ovulatory phase (OP), and midluteal phase (MLP) of 2 MCs. Overnight sleep was monitored using a Somnofy sleep monitor after each training session, and perceived recovery was assessed after 24 hours using self-report scales. MC phases were determined using the 3-step method, and noneumenorrheic MCs were retrospectively excluded from analysis. Results: MC phase had a main effect on wake after sleep onset (P ≤.001), with higher values in MLP (33 [22] min) than EFP (22 [19] min, P =.043) and OP (14 [9] min, P =.001), sleep efficiency (P =.033), with lower values in MLP (87% [6%]) than OP (90% [8%], P =.047), and light sleep (P =.023) with higher values in MLP (59% [6%]) than EFP (54% [7%], P =.037). Session type had a main effect on perceived recovery (P <.018) and perceived muscle soreness (P =.007), indicating lower perceived recovery and higher perceived muscle soreness following HIT compared to LIT (P <.001, P =.018, respectively). No interactions were found between MC phase and session type for any of the measured variables. Conclusions: Objective sleep quality, but not perceived recovery, was influenced by MC phase, as indicated by small impairments to multiple indices of objective sleep during MLP. There were no interactions between MC phase and session type, indicating that the effect of MC on sleep and recovery is consistent regardless of session type. [ABSTRACT FROM AUTHOR]

Purpose: The relationship between external load and creatine-kinase (CK) response at the team/position or individual level using Global Positioning Systems (GPS) has been studied. This study aimed to compare GPS-derived and Football Movement Profile (FMP) –derived CK-prediction models for national-team soccer players. The second aim was to compare the performance of general and individualized CK prediction models. Methods: Four hundred forty-four national-team soccer players (under 15 [U15] to senior) were monitored during training sessions and matches using GPS. CK was measured every morning from whole blood. The players had 19.3 (18.1) individual GPS-CK pairs, resulting in a total of 8570 data points. Machine learning models were built using (1) GPS-derived or (2) FMP-based parameters or (3) the combination of the 2 to predict the following days' CK value. The performance of general and individual-specific prediction models was compared. The performance of the models was described by R2 and the root-mean-square error (RMSE, in units per liter for CK values). Results: The FMP model (R2 =.60, RMSE = 144.6 U/L) performed similarly to the GPS-based model (R2 =.62, RMSE = 141.2 U/L) and the combination of the 2 (R2 =.62, RMSE = 140.3 U/L). The prediction power of the general model was better on average (R2 =.57 vs R2 =.37) and for 73% of the players than the individualized model. Conclusions: The results suggest that FMP-based CK-prediction models perform similarly to those based on GPS-derived metrics. General machine learning models' prediction power was higher than those of the individual-specific models. These findings can be used to monitor postmatch recovery strategies and to optimize weekly training periodization. [ABSTRACT FROM AUTHOR]

Purpose: Without appropriate standardization of exercise doses, comparing high- (HI) and low-intensity (LI) training outcomes might become a matter of speculation. In athletic preparation, proper quantification ensures an optimized stress-to-recovery ratio. This review aims to compare HI and LI doses by estimating theoretically the conversion ratio, 1:x, between HI and LI: How many minutes, x, of LI are equivalent to 1 minute of HI using various quantification methods? A scrutinized analysis on how the dose increases in relation to duration and intensity was also made. Analysis: An estimation was conducted across 4 categories encompassing 10 different approaches: (1) "arbitrary" methods, (2) physiological and perceptual measurements during exercise, (3) postexercise measurements, and comparison to (4a) acute and (4b) chronic intensity-related maximum dose. The first 2 categories provide the most conservative estimation for the HI:LI ratio (1:1.5–1:10), and the third, slightly higher (1:4–1:11). The category (4a) provides the highest estimation (1:52+) and (4b) suggests 1:10 to 1:20. The exercise dose in the majority of the approaches increase linearly in relation to duration and exponentially in relation to intensity. Conclusions: As dose estimations provide divergent evaluations of the HI:LI ratio, the choice of metric will have a large impact on the research designs, results, and interpretations. Therefore, researchers should familiarize themselves with the foundations and weaknesses of their metrics and justify their choice. Last, the linear relationship between duration and exercise dose is in many cases assumed rather than thoroughly tested, and its use should be subjected to closer scrutiny. [ABSTRACT FROM AUTHOR]

Purpose: The study had 3 purposes: (1) to develop an index using machine-learning techniques to predict the fitness status of soccer players, (2) to explore the index's validity and its relationship with a submaximal run test (SMFT), and (3) to analyze the impact of weekly training load on the index and SMFT outcomes. Methods: The study involved 50 players from an Italian professional soccer club. External and internal loads were collected during training sessions. Various machine-learning algorithms were assessed for their ability to predict heart-rate responses during the training drills based on external load data. The fitness index, calculated as the difference between actual and predicted heart rates, was correlated with SMFT outcomes. Results: Random forest regression (mean absolute error = 3.8 [0.05]) outperformed the other machine-learning algorithms (extreme gradient boosting and linear regression). Average speed, minutes from the start of the training session, and the work:rest ratio were identified as the most important features. The fitness index displayed a very large correlation (r =.70) with SMFT outcomes, with the highest result observed during possession games and physical conditioning exercises. The study revealed that heart-rate responses from SMFT and the fitness index could diverge throughout the season, suggesting different aspects of fitness. Conclusions: This study introduces an "invisible monitoring" approach to assess soccer player fitness in the training environment. The developed fitness index, in conjunction with traditional fitness tests, provides a comprehensive understanding of player readiness. This research paves the way for practical applications in soccer, enabling personalized training adjustments and injury prevention. [ABSTRACT FROM AUTHOR]

Competitive sport involves physical and psychological stressors, such as training load and stress perceptions, that athletes must adapt to in order to maintain health and performance. Psychological resilience, one's capacity to equilibrate or adapt affective and behavioral responses to adverse physical or emotional experiences, is an important topic in athlete training and performance. The study purpose was to investigate associations of training load and perceived sport stress with athlete psychological resilience trajectories. Sixty-one collegiate club athletes (30 females and 31 males) completed self-reported surveys over 6 weeks of training. Athletes significantly differed in resilience at the beginning of competitive training. Baseline resilience differences were associated with resilience trajectories. Perceived stress and training load were negatively associated with resilience. Physical and psychological stressors had a small but statistically significant impact on resilience across weeks of competitive training, indicating that both types of stressors should be monitored to maintain athlete resilience. [ABSTRACT FROM AUTHOR]

Purpose: Interval-training sets may be applied in a different sequence within a swimming training session. The aim of this study was to investigate the effect of different set sequences on performance and physiological responses in a training session. Methods: Twelve highly trained male swimmers performed 4 sessions in randomized order. Each session included a different combination of 2 training sets: set A–set C, set C–set A, set B–set C, or set C–set B. Set A consisted of 8 × 200 m at speed corresponding to lactate threshold (30-s recovery), set B included 8 × 100 m at maximum aerobic speed (30-s recovery), and set C included 4 × 50-m all-out swimming (2-min recovery). Performance and physiological responses (lactate concentration, pH, base excess, bicarbonate, heart rate, and heart-rate variability) were measured. Results: Performance in each set was similar between sessions irrespective of set sequence. Blood lactate, heart rate, and acid–base responses during set C were similar in all sessions, but blood lactate was higher in sets A and B during C–A and C–B sessions (P =.01). The overall blood lactate and acid–base response was higher in C–A and C–B sessions compared with A–C and B–C sessions, respectively (P =.01). Heart-rate variability in each set, separately as well as the overall session effect, did not differ and was thus independent to the set sequence applied. Conclusions: Training sessions including all-out swimming as a first set increase the magnitude of metabolic responses to the subsequent aerobic-dominated training set. [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]

Background: Little is known about the influence of kinetic chain strength and power on shoulder problems in handball players or the impact of participation-related shoulder load (PSL) during a season. Suboptimal activity of the kinetic chain during throwing might make the shoulder more vulnerable. Purpose: The purpose of this study was to assess 1) the association between pre-season measurements and shoulder problems among handball players and 2) whether pre-season strength and power influence the association between PSL and severity of shoulder problems. Study Design: Prospective observational cohort study. Methods: Pre-season measurements were done using the Isometric mid-thigh pull for lower body strength, a seated test for trunk rotation power (TRP) and isometric testing of external (ER) and internal rotation shoulder strength on 42 male players. Shoulder problems (prevalence, substantial prevalence, and severity score) were documented weekly through a season (31 weeks) with The Oslo Sports Trauma Research Center Overuse Questionnaire (OSTRC-O2) and PSL with the modified Borg rate of perceived exertion scale. Spearman´s correlation coefficient was applied to examine the association within the first aim, while a mixed model ANOVA was conducted to analyze the second aim. Results: A weak and negative correlation (rs=-0.34) was found between pre-season ER strength and the individual prevalence of shoulder problems (p=0.029). A main effect was found between PSL and the OSTRC-O2 severity score (p=<0.001) with higher severity scores observed with increased PSL. A significant interaction was found between PSL and pre-season TRP regarding their influence on the OSTRC-02 severity score (p=0.017). With higher PSL, a higher severity score was observed among players with pre-season TRP more than one standard deviation below the group's mean. Conclusions: The results indicate that low TRP may make the throwing shoulder more vulnerable to an increase in load. Looking beyond shoulder strength and load may therefore be important. Level of evidence: 3 [ABSTRACT FROM AUTHOR]

Purpose: Monitoring players' training load allows practitioners to enhance physical performance while reducing injury risk. The aim of this study was to identify the key external load indicators in professional U19 soccer. Methods: Twenty-four-professional Italian young (U19) soccer players were monitored by using the rating of perceived exertion (CR-10 RPE scale) and a wearable inertial sensor during the competitive season. Three main components were detected by a Principal Component Analysis (PCA): i) volume metabolic related component, ii) intensity mechanical stimuli component, and iii) intensity metabolic/mechanical component. We hence computed two scores (i.e. Performance [PERF] and total workload [WORK]) permitting to investigate the weekly microcycle. Results: Correlation analysis showed that scores (i.e. PERF and WORK) are low correlated (r = -0.20) suggesting that they were independent. Autocorrelation analysis showed that a weekly microcycle is detectable in all the scores. Two-way ANOVA RM showed a statistical difference between match day (MD) and playing position for the three PCA components and PERF score. Conclusion: We proposed an innovative approach to assess both the players' physical performance and training load by using a machine learning approach allowing reducing a large dataset in an objective way. This approach may help practitioners to prescribe the training in the microcycle based on the two scores. [ABSTRACT FROM AUTHOR]

The influence of aerobic variables on mixed martial arts (MMA) performance is currently unknown. This study aimed to compare the laboratory-measured aerobic variables of MMA participants to the external load and intensity of MMA sparring bouts to determine the effect of aerobic capacity on performance. Ten participants (age = 24 ± 2.8 years; mass = 74.3 ± 8.2 kg; stature = 176.8 ± 7.9 cm) completed the following: a treadmill-graded exercise test to measure V̇O2max, VT1 and VT2; 3 × 5 mins sparring bout equipped with a Catapult Optimeye S5 accelerometer recording Playerload (PLdACC) and Playerload per minute (PLdACC∙min−1), with a sessional rating of perceived exertion (sRPE) recorded as internal intensity. Median V̇O2max (53.3 ml∙kg∙min−1) was used to split the cohort into the top 50% and bottom 50%. Pearson's r correlations (BF10 ≥ 3) were calculated between GXT and sparring variables. V̇O2max (53.1 ± 5.9 ml∙kg∙min−1) was found to have very large (r ≥.70) linear relationships with PLdACC (161.4 ± 27.2 AU) and PLdACC∙min−1 (10.7 ± 1.8AU). The top 50% group maintained moderate sRPE (4-6AU) and greater PLdACC∙min−1 throughout the bout, with the bottom 50% group's sRPE moving from moderate to high (>7AU) indicating V̇O2max <53 ml∙kg∙min−1 is related to increased internal intensity. These data support the aerobic nature of MMA and may provide aerobic capacity targets for athletes and coaches to aim for during competition preparation. [ABSTRACT FROM AUTHOR]

Training load monitoring is employed to quantify training demands, to determine individual physiological adaptions and to examine the dose–response relationship, ultimately reducing the likelihood of injury and making a meaningful impact on performance. The purpose of this study is to explore the relationship between training load and injury in competitive swimmers, using the session rate of perceived exertion (sRPE) method. Data were collected using a prospective, longitudinal study design across 104 weeks. Data were collected from 34 athletes centralised in two of Swim Ireland's National Centres. Bayesian mixed effects logistic regression models were used to analyse the relationship between sRPE-TL and medical attention injuries. The average weekly swim volume was 33.5 ± 12.9 km. The weekly total training load (AU) averaged 3838 ± 1616.1. A total of 58 medical attention injury events were recorded. The probability of an association between training load and injury ranged from 70% to 98%; however, evidence for these relationships was deemed weak or highly uncertain. The findings suggest that using a single training load metric in isolation cannot decisively inform when an injury will occur. Instead, coaches should utilise monitoring tools to ensure that the athletes are exposed to an appropriate training load to optimise physiological adaptation. Future research should strive to investigate the relationship between additional risk factors (e.g., wellbeing, lifestyle factors or previous injury history), in combination with training load and injury, in competitive swimmers. [ABSTRACT FROM AUTHOR]

Featured Application: Both integrated game-based and resisted sprint training methods effectively enhance acceleration in professional women's football. Incorporating high-speed actions into training significantly improves sprint performance across distances, offering a practical solution during competitive periods. The recognition of high-speed demands in football has led elite academies to prioritize acceleration capabilities for player selection and promotion, particularly given their fundamental role in the motor skills of professional players and their impact on goal-related opportunities. This study explored the effectiveness of game-based versus resisted sprint training methods in enhancing the acceleration abilities of professional women's football players. Over the entire competitive period, the training load of 26 athletes (24.2 ± 3.7 years) was assessed using GPS devices, and sprint capabilities were evaluated through four 30-m acceleration tests spaced six weeks apart. Linear mixed models (LMMs) analyzed physical load parameters, including distance covered at high speeds, speed events, and maximum speed, with periods and players as fixed and random effects, respectively. Significant sprint performance improvements were observed across all intervals, particularly when high-intensity distance volumes were combined with resisted sprint training. Conversely, high-intensity running without additional stimuli also led to performance gains, albeit to a lesser extent. Both game-based and resisted sprint training methods were effective in enhancing acceleration capabilities, while the absence of specific sprint focus did not significantly alter sprint performance. These findings support the inclusion of tailored sprint training in athletic programs to optimize acceleration in women's football players. [ABSTRACT FROM AUTHOR]

Introduction: Vigorous physical activity (VPA) has been demonstrated to enhance cardiorespiratory fitness (CRF) in sedentary college students more effectively than other PA. However, differences in training volume may affect this outcome. This study examines the physiological, psychological, and internal training load (ITL) characteristics of VPA with varying volumes in a single session. Methods: Thirty sedentary college students were divided into three groups: high-intensity interval training (HIIT), sprint interval training (SIT), and threshold training (THR). PA process was monitored. The study measured various cardiorespiratory parameters, including heart rate (HR), respiratory waveform and amplitude, respiratory rate (RR), tidal volume (TV), minute ventilation volume (VE), fractional concentration of oxygen in end-tidal gas (O2%), fractional concentration of end-tidal carbon dioxide (CO2%), global oxygen consumption (VO2), carbon dioxide discharge (VCO2), and the amount of carbon dioxide in the air. The following physiological indicators were measured: carbon dioxide discharge (VCO2), Oxygen pulse (OP), and respiratory exchange ratio (RER). Additionally, subjective perception indicators were recorded, including the feeling scale (FS), rating of perceived exertion (RPE), and dual-mode model (DMM). The session-RPE (s-RPE) and Edward's TRIMP were used to measure ITL. Results: There were no significant differences in HR across the three conditions. THR had the highest level of TV (p = 0.043), but RR was significantly lower than that of HIIT and SIT (p < 0.01). HIIT had the highest levels of VO2, VCO2, O2%, and OP (p < 0.05). RPE was higher in HIIT and SIT compared to THR (p < 0.01), but the difference in FS was not significant. The DMM time-domain trajectories were similar in HIIT and THR. The correlation between exercise intensity, RPE, and FS was highest in THR group (r = 0.453, r = −0.58, r = −0.885). ITL did not show a significant difference between three conditions, but TRIMP and s-RPE readings were opposite in magnitude. Conclusion: This study proposes that using an appropriate amount of THR to foster interest and adaptive strength during the PA habit establishment period, incorporating HIIT to enhance exercise efficiency during the adaptation period, and implementing SIT to reduce the monotony may effectively enhance the cardiorespiratory fitness of sedentary college students and establish PA habit. [ABSTRACT FROM AUTHOR]

In energydominant disciplines, such as swimming, performance depends largely on the difference between the levels of fatigue and physical fitness: the greater this difference, the higher the probability of reaching a peak performance. The main challenge before major events such as the Olympic games is therefore in identifying the most efficient strategies to reduce the fatigue accumulated during previous mesocycles, while maintaining, or even improving the level of physical fitness. The most widespread strategy relies in the manipulation of training load parameters. This is the taper period, which has been shown to improve performance by ≈2% in elite athletes. However, tapering may not be sufficient for the most tired athletes. In this case, the strategy commonly used consists in combining the manipulation of training load with the implementation of recovery methods. Regardless of the strategy, we perceive that the challenge for athletes, coaches, and sport scientists is to estimate the level of cumulative fatigue as precisely as possible to individualize the recommendations. This relies not only on the identification of valid markers but also on the ability to interpret their variations over time. The objective of this article is to present the method initially developed in a European champion professional rugby team and now implemented with the French swimming team as part of its preparation for the Paris 2024 Olympic and Paralympic Games. More specifically, this article provides some details about the conception of the monitoring dashboard, and the method used to interpret changes over time to categorize the level of fatigue. [ABSTRACT FROM AUTHOR]

Identifying physiological changes that occur in response to workload demands can help to elucidate athlete management and recovery strategies. The purpose of this study was to compare the physical and physiological demands between men and women throughout the course of a collegiate soccer season. Men (N 5 23) and women (N 5 26) soccer players participated in blood draws before preseason (T1) and every 4 weeks thereafter (T2-T4). Workload was determined at all practices and games via heart rate and global positioning satellite monitoring systems. Repeated measures multivariate analysis of variance and linear mixed models were used to assess workload and biomarker responses throughout the season (p, 0.05). Both teams experienced the highest workloads during the first 4 weeks of the season (p, 0.05), which was followed by several biomarker perturbations. Sex-by-Time interactions were observed for total cortisol, growth hormone, insulin-like growth factor-1, thyroxine, thyroid-stimulating hormone, vitamin D, and omega 3 fatty acid index (p, 0.05). Additional Sex effects were observed for free and total testosterone, estrogen, prolactin, sex-hormone binding globulin, creatine kinase, and iron levels (p, 0.05). Women soccer players experienced further Time effects for free cortisol, iron, ferritin, and percent transferrin saturation (p, 0.05). Male soccer players experienced additional Time effects for total testosterone, estrogen, creatine kinase, interleukin-6, triiodothyronine, and ferritin (p, 0.05). Despite similar patterns of change in workloads, differential fluctuations in physiological markers were observed between the sexes. Understanding sex differences in response to comparable workloads may enhance exercise prescriptions for better athlete management plans. Additional strategies to increase iron may be warranted in female athletes. [ABSTRACT FROM AUTHOR]

This study verified the relationship between internal load (IL) and external load (EL) and their association on injury risk (IR) prediction considering machine learning (ML) approaches. Studies were included if: (1) participants were male professional soccer players; (2) carried out for at least 2 sessions, exercises, or competitions; (3) correlated training load (TL) with non-contact injuries; (4) applied ML approaches to predict TL and non-contact injuries. TL included: IL indicators (Rating of Perceived Exertion, RPE; Session-RPE, Heart Rate, HR) and EL indicators (Global Positioning System, GPS variables); the relationship between EL and IL through index, ratio, formula; ML indicators included performance measures, predictive performance of ML methods, measure of feature importance, relevant predictors, outcome variable, predictor variable, data pre-processing, features selection, ML methods. Twenty-five studies were included. Eleven addressed the relationship between EL and IL. Five used EL/IL indexes. Five studies predicted IL indicators. Three studies investigated the association between EL and IL with IR. One study predicted IR using ML. Significant positive correlations were found between S-RPE and total distance (TD) (r = 0.73; 95% CI (0.64 to 0.82)) as well as between S-RPE and player load (PL) (r = 0.76; 95% CI (0.68 to 0.84)). Association between IL and EL and their relationship with injuries were found. RPE, S-RPE, and HR were associated with different EL indicators. A positive relationship between EL and IL indicators and IR was also observed. Moreover, new indexes or ratios (integrating EL and IL) to improve knowledge regarding TL and fitness status were also applied. ML can predict IL indicators (HR and RPE), and IR. The present systematic review was registered in PROSPERO (CRD42021245312). [ABSTRACT FROM AUTHOR]

Background: The updated Oslo Sports Trauma Research Questionnaire on Health Problems (OSTRC-H2) has been translated into a limited set of languages and lacks full validation of its new measures. Purpose: To (1) translate, cross-culturally adapt, and evaluate the measurement properties of the OSTRC-H2 for the Slovenian population and (2) investigate the construct validity for the severity score and time lost due to a health problem. Study Design: Cohort study (diagnosis); Level of evidence, 3. Methods: The OSTRC-H2 was translated from English to Slovenian (OSTRC-H2-SLO) according to international guidelines. A 15-week study was conducted among 188 elite athletes, with a test-retest performed in the 10th week. Internal consistency, reliability, content validity, feasibility, and potential ceiling effects were investigated. Internal consistency was measured using the Cronbach alpha coefficient, while reliability was measured with the intraclass correlation coefficient (ICC). Construct validity was measured with the Spearman rank correlation coefficient (r S). Results: There was a 95% response rate and an 18% mean weekly prevalence of health problems. The OSTRC-H2-SLO showed excellent test-retest reliability (ICC, 0.94 [95% CI, 0.67-0.99]), with a Cronbach α of.93. A strong positive correlation was found between the OSTRC-H2-SLO severity score and days lost due to an acute injury (r S = 0.754), overuse injury (r S = 0.785), and illness (r S = 0.894) (P <.001 for all). Moderate to strong negative correlations were observed between severity score and total load (training and competition load in hours) as well as between days lost and total load (P <.001 for all). Conclusion: The OSTRC-H2-SLO was found to be valid, reliable, and well accepted among Slovenian athletes. The authors confirmed the questionnaire's construct validity and identified total load as an indicator of an increase in the severity score. Registration: NCT05471297 (ClinicalTrials.gov identifier). [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to evaluate the validity of the HandyGym portable flywheel device with an integrated rotary encoder in measuring force and power during iso-inertial exercises compared to a traditional reference system. Methods: In total, 10 trained volunteers (3 women, 7 men; age 25.2 ± 3.8 years) performed half-squats with five different load configurations using the HandyGym device. Concurrent measurements were obtained from HandyGym's rotary encoder and a criterion system (MuscleLab 6000 strain gauge and linear encoder). Five load configurations were tested, with 15 repetitions recorded per condition. The validity of the HandyGym measurements was assessed through mean bias, typical error of estimation (TEE), and Pearson correlation coefficients, with Bland–Altman plots used to analyze the agreement between the two systems. Results: The HandyGym showed high correlations with the reference system for both force (r = 0.76–0.90) and power (r = 0.60–0.94). However, systematic biases were observed, with the HandyGym consistently underestimating force and power at lower loads and overestimating power at higher loads. The TEE values indicated moderate to large errors, particularly in power measurements. Conclusion: The HandyGym provides valid force measurements with moderate bias, suitable for general monitoring. However, power measurements are less consistent, especially at higher loads, limiting the device's utility for precise assessments. Adjustments or corrections may be necessary for accurate application in professional contexts. [ABSTRACT FROM AUTHOR]

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Vigorous physical activity (VPA) has been demonstrated to enhance cardiorespiratory fitness (CRF) in sedentary college students more effectively than other PA. However, differences in training volume may affect this outcome. This study examines the physiological, psychological, and internal training load (ITL) characteristics of VPA with varying volumes in a single session. Methods: Thirty sedentary college students were divided into three groups: highintensity interval training (HIIT), sprint interval training (SIT), and threshold training (THR). PA process was monitored. The study measured various cardiorespiratory parameters, including heart rate (HR), respiratory waveform and amplitude, respiratory rate (RR), tidal volume (TV), minute ventilation volume (VE), fractional concentration of oxygen in end-tidal gas (O2%), fractional concentration of end-tidal carbon dioxide (CO2%), global oxygen consumption (VO2), carbon dioxide discharge (VCO2), and the amount of carbon dioxide in the air. The following physiological indicators were measured: carbon dioxide discharge (VCO2), Oxygen pulse (OP), and respiratory exchange ratio (RER). Additionally, subjective perception indicators were recorded, including the feeling scale (FS), rating of perceived exertion (RPE), and dual-mode model (DMM). The session-RPE (s-RPE) and Edward's TRIMP were used to measure ITL. Results: There were no significant differences in HR across the three conditions. THR had the highest level of TV (p = 0.043), but RR was significantly lower than that of HIIT and SIT (p < 0.01). HIIT had the highest levels of VO2, VCO2, O2%, and OP (p < 0.05). RPE was higher in HIIT and SIT compared to THR (p < 0.01), but the difference in FS was not significant. The DMM time-domain trajectories were similar in HIIT and THR. The correlation between exercise intensity, RPE, and FS was highest in THR group (r = 0.453, r = -0.58, r = -0.885). ITL did not show a significant difference between three conditions, but TRIMP and s-RPE readings were opposite in magnitude. Conclusion: This study proposes that using an appropriate amount of THR to foster interest and adaptive strength during the PA habit establishment period, incorporating HIIT to enhance exercise efficiency during the adaptation period, and implementing SIT to reduce the monotony may effectively enhance the cardiorespiratory fitness of sedentary college students and establish PA habit. [ABSTRACT FROM AUTHOR]

This study aimed to compare the microcycle load distribution between teams from different competitive levels. A total of 22 microcycles from one team of each competitive level (first division, 1st DIV, n = 32 players; second division, 2nd DIV, n = 23 players; third division, 3rd DIV, n = 23 players) were monitored using GPS (10 Hz, Catapult). During the match, a higher number of high accelerations (i.e., > 3 m/s, per min) were found in the 3rd DIV team compared to the 1st and 2nd DIV teams. On match day (MD) +1&+2, the 1st DIV team covered more total (per min, p < 0.001) and high-speed running distance (HSR per min, p < 0.001 and p = 0.042, respectively) than both the 2nd and 3rd DIV teams. The 2nd DIV team showed lower values in most distance-related variables (total distance covered per min, p < 0.001; running distance per min, p < 0.001; HSR per min, p < 0.001; and sprinting distance per min, p < 0.001) for both MD-4 and MD-3 compared to the 1st and 3rd DIV teams. In contrast, it showed higher sprinting distance per min (p < 0.001) on MD-2. In general, the 3rd DIV team showed higher values in the number of high accelerations (per min, p < 0.001) across all sessions. These results suggest that distance-related variables may be a priority when planning microcycles for the 1st DIV team, while accelerations are relevant for the 3rd DIV team. A higher emphasis on external load during MD-2 by the 2nd DIV team may explain the lower external loads across the microcycle. [ABSTRACT FROM AUTHOR]

Basketball players are prone to joint injuries due to the sport's high intensity and physical demands. Early prediction of injury risk is crucial for implementing effective prevention strategies. Incorporating biomechanics, this study focuses on basketball players at a university in Xi'an, China, aiming to develop a machine learning-based model to predict joint injury risk using easily collectable data such as training load, fatigue levels, and previous injury history. Considering regional differences, we observed that local and northern Chinese students are generally taller, while students from southern China are typically shorter. This anthropometric variation was included in our sampling and analysis. Utilizing data from 100 basketball players, the Random Forest algorithm achieved the best predictive performance with an accuracy of 85%. Key risk factors identified include high training load, elevated subjective fatigue scores, and a history of previous joint injuries. Additionally, biomechanical data were integrated to elucidate the underlying mechanisms of joint injuries, and the cellular responses to injury were explored. The results demonstrate that even with limited data types, machine learning methods can effectively predict joint injury risk among basketball players, providing a valuable tool for injury prevention. [ABSTRACT FROM AUTHOR]

The study aimed (a) to determine the conditional demands of external load based on the submaximal intensity periods (SubMIP) during the competitive micro-cycle, (b) to compare the number and duration of SubMIP events demanded in the different sessions carried out in the competitive micro-cycle and, additionally, (c) to compare these demands based on the SubMIP depending on the specific position occupied by the football players during the competitive micro-cycle. A total of 77 training sessions were analyzed during 15 competitive micro-cycles and 15 official league matches during the 2019-20 season (Azerbaijan Premier League) obtaining a total of 1,037 individual records from 22 players. Data were collected using GPS devices. To determine the percentage of the number of daily SubMIP events with respect to those found in the competition, these events were also relativized based on the individual profile showed by player in competition. The main findings of the study were the existence of significant differences (p ≤ .05) in each of the variables between training days/competition and positions based on the SubMIP. Metrics such as distance at speed > 19.8 km/h (HSR), distance at speed > 25.2 km/h (Sprint), acceleration density (AccDens) and distance at high metabolic intensity > 25.5 W/kg (HMLD) accumulated values > 50 % of the number of SubMIP events on some days of the microcycle. However, other metrics displayed much lower ranges (less than 15 %) compared to the competition in terms of the number of events and time above the threshold established in meters per minute (Mmin) and mean metabolic power (MetPow) variables. These new findings suggest that it is appropriate to explore new alternatives for load control in team sports. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effects of a 4-week intervention combining smallsided games (SSGs) and high-intensity interval training (HIIT) on physical fitness in collegiate male soccer players. Methods: Twenty-one soccer players were randomly assigned to either the HIIT + SSGs group (n = 11) or a control group (n = 10). Physical fitness was assessed at baseline and 1-week post-intervention, including countermovement jump (CMJ), change of direction (COD) test, sprint test, repeated sprint ability (RSA) test, and 30-15 Intermittent Fitness Test (30-15IFT). The intervention comprised eight sessions over 4 weeks: four SSGs and four HIIT. Results: The intervention group showed small to moderate improvements: mean RSA improved by 4.5% (p = 0.07), CMJ increased by 3.2% (p = 0.12), and 30-15IFT scores enhanced by 6.8% (p = 0.09). Key predictors of group membership included heart rate load per minute (OR 1.602) and various GPS variables. Conclusion: The 4-week intervention combining SSGs with HIIT did not produce statistically significant improvements in most physical fitness variables compared to the control group. Although there were positive trends in variables such as RSA and 30-15IFT, these changes were modest and not statistically significant. The results suggest that while the combined SSGs and HIIT approach shows potential, its impact on physical fitness over a 4-week period is limited, with some variables, like CMJ, even showing decreases. [ABSTRACT FROM AUTHOR]

Copyright of Retos: Nuevas Perspectivas de Educación Física, Deporte y Recreación is the property of Federacion Espanola de Asociaciones de Docentes de Educacion Fisica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of the study was to examine the match-running load of female soccer players competing at distinct age groups (U15, U18 and senior cohorts) belonging to the same professional club, over a competitive season. The external load variables of the official matches were monitored with Global Positioning System (GPS) technology: total distance (TD), at >18 km·h−1 (running), at >21 km·h−1 (high-speed running, HSR) and at >24 km·h−1 (sprint, SPR) distances, efforts at >85% of the maximal sprint speed (>85% MSS), acceleration load (aLoaD), accelerations (ACC2 and ACC3, >2 and >3 m·s−2) and decelerations (DEC2 and DEC3 <−2 and <−3 m·s−2). Overall, distances covered at running, HSR and sprinting were greater for senior players than their younger peers (U15 and U18; p < 0.05). Regarding HSR and sprints, no difference was found for sprints accumulated by central defender (CD) players in comparison to U18 and U15 (p > 0.05). In addition, U18 and senior players engaged more often in ACC and DEC, >2 and >3 m·s−2, respectively, than U15 players (p < 0.05). In conclusion, older female soccer players are exposed to higher match load than their younger peers. These findings could be useful for soccer coaches to design specific speed development programmes across the long-term athletic development pathway. [ABSTRACT FROM AUTHOR]

Background: Elite sport is continuously evolving. World records keep falling and athletes from a longer list of countries are involved. Purpose: This commentary was designed to provide insights into present and future trends associated with world-class endurance training based on the perspectives, experience, and knowledge of an expert panel of 25 applied sport scientists. Results: The key drivers of development observed in the past 10–15 years were related to (1) more accessible scientific knowledge for coaches and athletes combined with (2) better integration of practical and scientific exchange across multidisciplinary perspectives within professionalized elite athlete support structures, as well as (3) utilization of new technological advances. Based on these perspectives, we discerned and exemplified the main trends in the practice of endurance sports into the following categories: better understanding of sport-specific demands; improved competition execution; larger, more specific, and more precise training loads; improved training quality; and a more professional and healthier lifestyle. The main areas expected to drive future improvements were associated with more extensive use of advanced technology for monitoring and prescribing training and recovery, more precise use of environmental and nutritional interventions, better understanding of athlete–equipment interactions, and greater emphasis on preventing injuries and illnesses. Conclusions: These expert insights can serve as a platform and inspiration to develop new hypotheses and ideas, encourage future collaboration between researchers and sport practitioners, and, perhaps most important, stimulate curiosity and further collaborative studies about the training, physiology, and performance of endurance athletes. [ABSTRACT FROM AUTHOR]

Purpose: To gain knowledge on the beliefs and practices of football practitioners applying high-speed and sprint running exposure programming strategies. Methods: One hundred two football practitioners from 22 different countries participated in a study consisting of a survey including 5 domains: demographic and professional characteristics (Who); importance of high-speed and sprint running exposure for physical-capability development, preparation for competition, and injury-prevention strategies (Why); exposure timing (When); methodological procedures for exposure monitoring and training scheduling (What); and effectiveness of common training practices (How). Data were analyzed using a combination of descriptive statistics, generalized mixed effects, and multinomial logistic regression models. Results: Data revealed 5 main findings: (1) overall agreement on the importance of exposure for physical-capability development, preparation for competition, and injury-prevention strategies; (2) different exposure timing and selective training scheduling for starting and nonstarting players across typical and congested weeks; (3) lack of consensus on the conceptual constructs defining high-speed and sprint running metrics and the methodological procedures used for monitoring; (4) a probable association between match-related outcomes and exposure strategies used in training; and (5) a broad range of training methods considered effective to elicit exposure. Conclusions: This study provides actionable insights into the planning, implementing, and monitoring strategies for high-speed and sprint running exposure in football. While some conform with the evidence on high-speed and sprint running training in football, further research and professional debate are warranted to develop empirical knowledge and provide pragmatic recommendations to help practitioners in adopting evidence-informed decisions. [ABSTRACT FROM AUTHOR]

Purpose: To quantify match load associated with padel and compare responses with both singles and doubles tennis. Methods: On separate days, 12 participants (7 men and 5 women) played 60-minute padel (PADEL), singles tennis (SINGLES), and doubles tennis (DOUBLES) simulated games. Participants wore a 10-Hz GPS/100-Hz triaxial accelerometer unit and heart-rate monitor. Exercise-related sensations and blood lactate concentration were monitored every 20 minutes. Match-play characteristics (temporal structure) and shot selection were derived from video analysis. Vertical jump ability was assessed before and after each game. Results: Heart rate, exercise-related sensations (overall perceived exertion and limb discomfort), and physical load (total distance covered, PlayerLoad, acceleration density and load) for SINGLES were higher compared with DOUBLES and PADEL (all P ≤.05). Blood lactate concentrations remained low (1–2 mmol·L−1) and did not differ between conditions. Effective playing time (P <.001) was lower in SINGLES and DOUBLES compared with PADEL. The number of forehands (P =.002) and backhands (P <.001) was greater for SINGLES than for DOUBLES and PADEL. The number of volleys/smashes and lobs (P <.05) was greater for PADEL compared with SINGLES and DOUBLES. Performance for squat, countermovement, and multirebound jumps was similarly reduced below baseline after match play (P <.05), independent of condition. Conclusion: Padel imposes a unique match load on players that is different from singles tennis and more closely resembles that of doubles tennis. Cardiovascular stimulation and physical load are highest in singles tennis, while padel sees players hit a larger variety of shots with higher effective playing percentages. [ABSTRACT FROM AUTHOR]

Purpose: Mental fatigue (MF) can impair physical performance in sport. We tested the hypothesis that cognitive load alone, and intermixed with standard resistance training, would induce MF, increase rating of perceived exertion (RPE), alter perception of weight lifting and training, and impair cycling time-trial performance. Methods: This 2-part study employed a within-participant design. In part 1, after establishing leg-extension 1-repetition maximum (1RM), 16 participants lifted and briefly held weights at 20%, 40%, 60%, and 80% of 1RM. RPE and electromyography (EMG) were measured for each lift. During the testing sessions, participants completed cognitive tasks (MF condition) or watched neutral videos (control condition) for 90 minutes before lifting the weights. In part 2, they completed submaximal resistance training comprising 6 weight training exercises followed by a 20-minute cycling time trial. In the MF condition, they completed cognitive tasks before and between weight training exercises. In the control condition, they watched neutral videos. Mood (Brunel Mood Scale), workload (National Aeronautics and Space Administration Task Load Index), MF-visual analogue scale (MF-VAS), RPE, psychomotor vigilance, distance cycled, power output, heart rate, and blood lactate were measured. Results: In part 1, the cognitive task increased lift-induced RPE (P =.011), increased MF-VAS (P =.002), and altered mood (P <.001) compared with control. EMG did not differ between conditions. In part 2, the cognitive tasks increased RPE (P <.001), MF-VAS (P <.001), and mental workload (P <.001), but reduced cycling time-trial power (P =.032) and distance (P =.023) compared with control. Heart rate and blood lactate did not differ between conditions. Conclusion: A state of MF induced by cognitive load, alone or intermixed with physical load, increased RPE during weight lifting and training and impaired subsequent cycling performance. [ABSTRACT FROM AUTHOR]

Abstract Background Blood flow restriction (BFR) resistance training has demonstrated efficacy in promoting strength gains beneficial for rehabilitation. Yet, the distinct functional advantages of BFR strength training using high-load and low-load protocols remain unclear. This study explored the behavioral and neurophysiological mechanisms that explain the differing effects after volume-matched high-load and low-load BFR training. Methods Twenty-eight healthy participants were randomly assigned to the high-load blood flow restriction (BFR-HL, n = 14) and low-load blood flow restriction (BFR-LL, n = 14) groups. They underwent 3 weeks of BFR training for isometric wrist extension at intensities of 25% or 75% of maximal voluntary contraction (MVC) with matched training volume. Pre- and post-tests included MVC and trapezoidal force-tracking tests (0–75%–0% MVC) with multi-channel surface electromyography (EMG) from the extensor digitorum. Results The BFR-HL group exhibited a greater strength gain than that of the BFR-LL group after training (BFR_HL: 26.96 ± 16.33% vs. BFR_LL: 11.16 ± 15.34%)(p = 0.020). However, only the BFR-LL group showed improvement in force steadiness for tracking performance in the post-test (p = 0.004), indicated by a smaller normalized change in force fluctuations compared to the BFR-HL group (p = 0.048). After training, the BFR-HL group activated motor units (MUs) with higher recruitment thresholds (p

Optimal load training is a method of training that aims to maximize power output. This is achieved by arranging optimal loads (optimal ratios of load intensity and load volume) during strength training. The fixed load intensity and number of repetitions employed in traditional strength training. The present study will investigate the applicability of these two load arrangements to female elite boxers. Twenty-four elite female boxers were divided into three groups [optimal load (OL = 8), traditional load (TL = 8) and control group (CG = 8)]. The six-week intervention consisted of strength training with different loading arrangements. The punching ability and strength were tested before and after the intervention. We found that optimal load training enhances a boxer's punching ability and economy, which aligns with the demands of boxing and is suitable for high-level athletes, whose strength training loads require a more individualised and targeted approach. [ABSTRACT FROM AUTHOR]

Introduction: Functional threshold power (FTP) has recently become a crucial metric for evaluating cycling performance. FTP represents an estimate of the maximal steady state of blood lactate concentrations during long-term cycling, assessed as the average power value in a 20-minute test (FTP20). However, the sports performance parameters reflected by FTP20 require further confirmation through laboratory tests. This study aimed to investigate the relationship between FTP20 and sports performance parameters. Methods: Twenty-five well-trained high school cyclists performed the FTP20 test and graded exercise tests with maximum effort. The FTP20 and various sports performance parameters, such as oxygen uptake, lactic acid, and heart rate, are presented as the mean and standard deviation. Pearson's correlation coefficient (r) was used to examine the correlations between FTP20 and sports performance parameters. Results: FTP20 was significantly correlated with maximum oxygen uptake (V̇ O2max), maximum aerobic power (MAP), peak power output, oxygen uptake at onset of blood lactate accumulation (OBLAvo2), power output at onset of blood lactate accumulation (OBLApower), heart rate at onset of blood lactate accumulation (OBLAHR), oxygen uptake at individual lactate threshold (ILT vo2), power output at individual lactate threshold (ILTpower), and average heart rate (HRavg) (r = -0.413-0.877). FTP20 was most strongly correlated with V̇ O2max (r = 0.857) and MAP (r = 0.877). Conclusion: This study found that key factors affecting the FTP20 included sports performance parameters such as V̇ O2max, MAP, OBLAvo2, and OBLApower. Therefore, V̇ O2max, muscle strength, and endurance of the lower body muscles should be improved to enhance the pedaling power and speed of high school cyclists in Taiwan during prolonged cycling. [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]

A comprehensive examination of the external and internal workloads in collegiate women's lacrosse athletes has yet to be reported. Thus, the primary purpose of this study was to determine the absolute and relative external and internal training and game workloads of National Collegiate Athletic Association (NCAA) Division II women's lacrosse athletes throughout an entire season. Data from 19 Division II women's lacrosse athletes were analyzed, encompassing each training session and game across an entire competitive season (February-May). External workloads were assessed using a wearable global positioning system, whereas internal workloads were determined through heart rate (HR) variables and session rating of perceived exertion. Game days were associated with significantly (p < 0.05) greater absolute external and internal workloads. However, when comparing workloads relative to session duration, relative workloads between training and games were no longer significant (p > 0.05) for total distance, high-speed running (≥15 km⋅h-1), HR-derived training impulse, or caloric expenditure. Nonetheless, relative sprint distance (>19 km⋅h-1) was significantly lower during games, whereas high-intensity accelerations (>2 m⋅s-2) and decelerations (<-2 m⋅s-2) were significantly greater during training compared with games (p < 0.05). Practical applications of these findings suggest that coaches can better prepare athletes for game day conditions by adjusting training plans to replicate the duration and intensity of games. Overall, this comprehensive examination of internal and external workloads provides valuable data for coaches and practitioners to support performance comparisons, rehabilitation protocols, and workload analyses in collegiate women's lacrosse athletes. [ABSTRACT FROM AUTHOR]

Integrating running gait coordination assessment into athlete monitoring systems could provide unique insight into training tolerance and fatigue-related gait alterations. This study investigated the impact of an overload training intervention and recovery on running gait coordination assessed by field-based self-testing. Fifteen trained distance runners were recruited to perform 1-week of light training (baseline), 2 weeks of heavy training (high intensity, duration, and frequency) designed to overload participants, and a 10-day light taper to allow recovery and adaptation. Field-based running assessments using ankle accelerometry and online short recovery and stress scale (SRSS) surveys were completed daily. Running performance was assessed after each training phase using a maximal effort multi-stage running test-to-exhaustion (RTE). Gait coordination was assessed using detrended fluctuation analysis (DFA) of a stride interval time series. Two participants withdrew during baseline training due to changed personal circumstances. Four participants withdrew during heavy training due to injury. The remaining nine participants completed heavy training and were included in the final analysis. Heavy training reduced DFA values (standardised mean difference (SMD) = −1.44 ± 0.90; p = 0.004), recovery (SMD = −1.83 ± 0.82; p less than 0.001), performance (SMD = −0.36 ± 0.32; p = 0.03), and increased stress (SMD = 1.78 ± 0.94; p = 0.001) compared to baseline. DFA values (p = 0.73), recovery (p = 0.77), and stress (p = 0.73) returned to baseline levels after tapering while performance trended towards improvement from baseline (SMD = 0.28 ± 0.37; p = 0.13). Reduced DFA values were associated with reduced performance (r2 = 0.55) and recovery (r2 = 0.55) and increased stress (r2 = 0.62). Field-based testing of running gait coordination is a promising method of monitoring training tolerance in running athletes during overload training. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai University of Sport is the property of Editorial Department of Journal of Shanghai University of Sport and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Prescribing correct training loads in strength- and power-based sports is essential to eliciting performance improvements for athletes. Concurrently, testing strength for the prescription of training loads should be accurate and safe with minimal disruption or fatigue inducement to the athlete. The purpose of this study was to develop a prediction equation in female athletes for the three-repetition maximum (3RM) squat using the isometric mid-thigh pull and basic anthropometric assessments that could be practically applied to support training prescriptions. Female athletes (n = 34) were recruited from netball, volleyball, basketball, and soccer across a spectrum of competitive standards. Each athlete's weight, standing height, seated height, arm span, and biacromial breadth were recorded, and then, on separate occasions separated by at least 48 h, each athlete completed a 3RM squat test and an isometric mid-thigh pull (IMTP) assessment. IMTP variables of peak force and time-dependent force at 50, 100, 150, 200, and 250 ms, as well as anthropometric measures, were used to develop a prediction equation. Squat strength was low-to-moderately correlated with peak force (r = 0.386); force at 100 ms (r = −0.128), 150 ms (r = −0.040), and 200 ms (r = −0.034); standing height (r = 0.294); and biacromial breadth (r = −0.410). Stepwise multiple regression significantly (p < 0.05) explained 26% of the 3RM squat strength variation using peak force and force at 100 ms, resulting in the following equation: Predicted 3RM squat (kg) = [6.102 + (Peak Force × 0.002) − (Force@100 ms × 0.001)]2. The reported equation's predictive accuracy was tested using the same testing protocols following 6–8 weeks of training in a sub-cohort of athletes (n = 14). The predicted and actual recorded 3RM values were not significantly (p = 0.313) different, supporting the use of the IMTP as a test that contributes informative values for use in a predictive equation for training prescription and thus reducing the testing and fatigue-inducing impost on female athletes. However, the 95% CI (−4.18–12.09) indicated predicted values could differ in excess of 10 kg. This difference could lead to an excessive load prescription for an athlete's training program, indicating caution should be taken if using the described method to predict 3RM squat values for programming purposes. [ABSTRACT FROM AUTHOR]

Objectives: The coronavirus disease (COVID-19) had a major impact on sleep and training behavior in adolescent athletes. A crucial sleep parameter is midsleep time, which illustrates the midpoint between sleep onset and offset. The aim of this investigation was to examine the impact of chronotype, age, sex, pandemic phase, weekend, and training habits on midsleep time. The sample consisted of German elite adolescent basketball athletes (N = 91, 15.75 ± 1.15 years, female = 39.46%). Method: Data were collected through a 10-day subjective monitoring program during three different pandemic phases, with more severe restrictions in phase 1. In total, 1146 measurement points were analyzed. A linear mixed model approach was used for the evaluation. Results: A negative linear association between chronotype and midsleep time was revealed. A negative effect was identified for phases 2 and 3. The weekend parameter showed a positive effect, which may illustrate the occurrence of social jetlag. The main finding of this investigation is that a morning chronotype distribution was associated with earlier midsleep timing throughout the entire survey period. Conclusion: The results acknowledge that chronotype is one of the main influencing parameters for midsleep time. The study represents a useful contribution to the research of chronotype and sleep behavior in athletes, with a focus on the major impact of the COVID-19 pandemic. [ABSTRACT FROM AUTHOR]

Monitoring training load, recovery, and wellness in maturation ages is even more relevant than in adulthood, especially during congested schedules. The objective of this study was to quantify and describe the differences in external and internal load, recovery, and perceived wellness in elite under-16 female players during a period of three competitions in seven days based on their participation during matches. An observational design was used to quantify the external load (total distance, high-speed distance, and PlayerLoad) and internal load (differential sRPE), as well as the recovery and wellness of 18 international under-16 players during a development tournament. The external load pattern of the starting players was undulating, with matches showing the highest internal load values compared to training sessions and non-starters. Non-starter players (whether training or matches) showed similar external load and differential sRPE values throughout the tournament (p > 0.05). Starting players experienced higher internal load than non-starters during matches (p < 0.037), without differences between training sessions (p > 0.05). No changes were seen in wellness or recovery (all p-values > 0.05), except for non-starters in Session 3 compared to Session 7 (p = 0.024). Starting players had more weekly total minutes (p = 0.018), differential sRPE (breath: p = 0.002; leg: p = 0.002; cognitive: p = 0.003), total distance (p = 0.003), and PlayerLoad (p = 0.008) than non-starters. Our results indicate differing load patterns between starters and non-starters, which do not affect wellness and recovery differently. Starters accumulate more weekly total load. Coaches can use these findings to guide decisions and load compensations in high competition contexts for young female soccer players. [ABSTRACT FROM AUTHOR]

We aimed to (1) compare external training loads obtained in futsal players during pre-season and in-season training weeks to explore how these loads are periodized by the coaching staff; and (2) compare the external training loads using the match day minus approach during the pre-season and in-season periods to determine how the within-microcycle training load varies between these periods. A total of 432 recordings were obtained of twelve national-level male amateur players using IPS devices. These data were collected over four consecutive microcycles from the beginning to the end of the pre-season, as well as during four additional consecutive microcycles at the start of the in-season. The external load variables evaluated were: total distance covered (TD; m), relative distance covered (Drel; m/min), high-speed running (HSR; m > 18.8 km/h), sprint distance (SPR; m > 25.2 km/h), number of intense accelerations (ACC; >2.5 m/s2) and decelerations (DEC; >−2.5 m/s2). Results indicated significant week-by-week variation (p < 0.05) in all external load variables during the pre-season. During the in-season, significant variations (p < 0.05) were observed only in Drel, HSR, and ACC. In both phases, all variables were higher (p < 0.05) two days before the match. In conclusion, it is important to consistently quantify the external loads of futsal players to ensure appropriate variation in loading and tapering within the microcycle, as well as during the pre-season and in-season periods. [ABSTRACT FROM AUTHOR]

The relationship between heart rate variability (HRV) and training load in team-sport is unknown. We therefore assessed relations between completed training-load in the previous 1-, 3- and 7-days and waking HRV in professional Australian Rules Football. Linear-mixed models analysed changes in HRV, considering training load from the previous 1-, 3- and 7-days. Total Distance (TD), distance >14.4 km ‧ h−1 (HSR) and >24.9 km ‧ h−1 (Sprint-Distance), duration >85% max heart rate and Rating of Perceived Exertion were included as independent variables. Sub-group analysis of season-phase and years of professional experience was also conducted. Increased three-day Sprint-Distance reduced HRV in the first 8-weeks of pre-season (−13.1 ms, p = 0.03) and across the data collection period (−3.75 ms, p = 0.01). In first-year players, higher previous-day (−63.3 ms, p=0.04) and seven-day TD (−38.2 ms, p = 0.02) reduced HRV, whilst higher seven-day HSR increased HRV (34.5 ms, p = 0.01). In players with five-to-seven years of professional experience, higher three-day (−14.4 ms, p = 0.02) and seven-day TD (−15.7 ms, p = 0.01) reduced HRV, while higher three-day HSR increased HRV (12.5 ms, p = 0.04). In players with greater than eight years of professional experience, higher previous-day Sprint-Distance reduced HRV (−13.1 ms, p < 0.008). Completed training load across the previous 7-days influences HRV, but the relation between variables is complex and influenced by professional experience and season-phase. [ABSTRACT FROM AUTHOR]

Aim: Greater quantification and characterisation of training load (TL) throughout Live-high, train-high (LHTH) altitude (ALT) training is required to identify periodisation strategies that may lead to physiological and performance improvements in swimmers. Purpose: This study aimed to examine the physiological responses and performance outcomes of 14 high-performance swimmers (FINA points: 836.0 ± 35.1) following 3 weeks of LHTH at 2320 m, while characterising the training load periodisation strategy adopted during the intervention. Methods: Haemoglobin (Hb) mass was measured pre-, 7 and 14 days post-ALT via CO rebreathing. Performance in each athlete's primary event at national standard meets were converted to FINA points and compared from pre-to-post-ALT. TL was quantified at sea level (SL) and ALT through session rating of perceived exertion (RPE), where duration of each session was multiplied by its RPE for each athlete, with all sessions totalled to give a weekly TL. Pre-to-post-ALT changes were evaluated using repeated-measures ANOVA. Results: Hb mass increased significantly from 798 ± 182 g pre-ALT to 828 ± 187 g at 7 days post (p = 0.013) and 833 ± 205 g 14 days post-ALT (p = 0.026). Weekly TL increased from SL (3179 ± 638 au) during week one (4797 ± 1349 au, p < 0.001) and week two (4373 ± 967 au, p < 0.001), but not week three (3511 ± 730 au, p = 0.149). No evidence of improved SL swimming performance was identified. Conclusion: A periodisation strategy characterised by a sharp spike in TL followed by a slight de-load towards the end of a LHTH intervention led to improved physiological characteristics but no change in the competitive performance of high-performance swimmers. [ABSTRACT FROM AUTHOR]

Ground reaction force (GRF) data is often collected for the biomechanical analysis of running, due to the performance and injury risk insights that GRF analysis can provide. Traditional methods typically limit GRF collection to controlled lab environments, recent studies have looked to combine the ease of use of wearable sensors with the statistical power of machine learning to estimate continuous GRF data outside of these restrictions. Before such systems can be deployed with confidence outside of the lab they must be shown to be a valid and accurate tool for a wide range of users. The aim of this study was to evaluate how accurately a consumer-priced sensor system could estimate GRFs whilst a heterogeneous group of runners completed a treadmill protocol with three different personalised running speeds and three gradients. Fifty runners (25 female, 25 male) wearing pressure insoles made up of 16 resistive sensors and an inertial measurement unit ran at various speeds and gradients on an instrumented treadmill. A long short term memory (LSTM) neural network was trained to estimate both vertical $(GRF_v)$ (G R F v) and anteroposterior $(GRF_{ap})$ (G R F a p) force traces using leave one subject out validation. The average relative root mean squared error (rRMSE) was 3.2% and 3.1%, respectively. The mean $(GRF_v)$ (G R F v) rRMSE across the evaluated participants ranged from 0.8% to 8.8% and from 1.3% to 17.3% in the $(GRF_{ap})$ (G R F a p) estimation. The findings from this study suggest that current consumer-priced sensors could be used to accurately estimate two-dimensional GRFs for a wide range of runners at a variety of running intensities. The estimated kinetics could be used to provide runners with individualised feedback as well as form the basis of data collection for running injury risk factor studies on a much larger scale than is currently possible with lab based methods. [ABSTRACT FROM AUTHOR]

Purpose: Investigate acute locomotor, internal (heart rate (HR) and ratings of perceived exertion (RPE)) and neuromuscular responses to using wearable resistance loading for soccer-specific training. Methods: Twenty-six footballers from a French 5th division team completed a 9-week parallel-group training intervention (intervention group: n = 14, control: n = 12). The intervention group trained with wearable resistance (200-g on each posterior, distal-calf) for full-training sessions on Day + 2, D + 4 and unloaded on D + 5. Between-group differences in locomotor (GPS) and internal load were analyzed for full-training sessions and game simulation drills. Neuromuscular status was evaluated using pre- and post-training box-to-box runs. Data were analyzed using linear mixed-modelling, effect size ±90% confidence limits (ES ± 90%CL) and magnitude-based decisions. Results: Full-training sessions: Relative to the control, the wearable resistance group showed greater total distance (ES [lower, upper limits]: 0.25 [0.06, 0.44]), sprint distance (0.27 [0.08, 0.46]) and mechanical work (0.32 [0.13, 0.51]). Small game simulation (<190 m2/player): wearable resistance group showed small decreases in mechanical work (0.45 [0.14, 0.76]) and moderately lower average HR (0.68 [0.02, 1.34]). Large game simulation (>190 m2/player): no meaningful between-group differences were observed for all variables. Training induced small to moderate neuromuscular fatigue increases during post-training compared to pre-training box-to-box runs for both groups (Wearable resistance: 0.46 [0.31, 0.61], Control: 0.73 [0.53, 0.93]). Conclusion: For full training, wearable resistance induced higher locomotor responses, without affecting internal responses. Locomotor and internal outputs varied in response to game simulation size. Football-specific training with wearable resistance did not impact neuromuscular status differently than unloaded training. [ABSTRACT FROM AUTHOR]

Background: Football, as the most popular sport worldwide, has long been under suspicion of causing varus knee alignment as early as adolescence. However, no causal relationship has yet been found. The first step to do so would be to determine the prevalence of lower leg malalignment among male junior football players depending on age, performance level and the number of active seasons played. Methods: Leg axis alignment in frontal plane was determined in male junior football players of different age levels between 7 and 18 years by measuring the intercondylar/intermalleolar distance (ICD/IMD) in an upright position. In addition to anthropometric data, multiple sport-specific data such as the start of their football career or training time per week were collected by means of questionnaires (clinical trial registration number: DRKS00020446). Results: 207 male junior football players were included in this survey. The mean age was 12.8 years. Within the group of 15 to 18 year olds, the prevalence of varus knee malalignment was highest at just under a third (32.1%). In the subpopulation that played actively for more than ten seasons, 28.9% showed varus leg axis. Regarding performance level, the highest IMD/ICD values and highest prevalence of varus alignment were found among football players who play on a semi-professional level (16.7%), compared to amateur (11.4%) and high-performance levels (2.8%). Conclusions: Further research is necessary to investigate if this high prevalence of varus knee in children of a higher age and higher playing levels is due to the selection bias of football players with varus knee or a real development of varus knee in individuals. [ABSTRACT FROM AUTHOR]

Objectives: To map and summarise the sports coaches' and support staff's perspectives on athlete monitoring to explore the breadth of literature, identify knowledge gaps and inform future research. Design: Scoping review based on the Joanna Briggs Institute (JBI) methodology. Methods: SPORTDiscus, MEDLINE, APA PsycInfo, and Embase databases were searched in English until 6 September 2022. The inclusion criteria were (1) coach(es) and/or support staff were explicitly questioned about their knowledge, perceptions, understanding, opinions, and/or applied practice of athlete monitoring; (2) results could be directly attributed to coach(es) and/or support staff; (3) primary research projects that are available as full-text. Exclusion criteria were applied for grey literature. The data were extracted into a custom-made data charting spreadsheet. Results: From the 4381 identified records, 42 met the eligibility criteria. Almost all the studies were conducted within the Anglosphere and at the national or international level. The main reasons for coaches and support staff to implement athlete monitoring were to reduce injury and illness, inform the training program, and improve or maintain performance. While training load monitoring is generally seen as valuable the coaches and support staff acknowledged that there was no perfect scientific approach to monitoring athletes and believed it should be part of the bigger picture, emphasising communication. Conclusions: There has been a recent surge in research demonstrating that athlete monitoring extends beyond quantitative information and encompasses non-quantified subjective information. This further substantiates that coaches and support staff will remain central to athlete monitoring, even amidst the anticipated technological progress. [ABSTRACT FROM AUTHOR]

Recently, we published self-reported data concerning the perceived effects of the menstrual cycle and hormonal contraceptives on the training and performance of 1086 female athletes participating in 57 sports. However, studies comparing differences between sports with large sample sizes are lacking. The aim of this ancillary study was to compare the impact of the menstrual cycle and hormonal contraceptives on training and performance between the three largest sports in the cohort, that is, football, handball, and orienteering, as well as the knowledge and support provided to the female athletes engaged in these sports. The results are from a web-based questionnaire completed by 312 football players, 243 handball players, and 93 orienteers. A total of 54% of the orienteers planned their training based on the menstrual cycle, which was a higher proportion compared to football (45%) and handball (29%) players (p < 0.05). Fewer football players believed that the menstrual cycle had an impact on their performance during training and competition compared to the two other sports. A high proportion of the athletes used hormonal contraceptives in all three sports, but a lower proportion of the orienteers (40%) used hormonal contraceptives compared to football (76%) and handball players (66%) (p < 0.05). Football and handball players received overall more support than orienteers, and the support was mostly provided by a physiotherapist and/or a strength and conditioner coach besides the main coach. These findings demonstrate that the perceived influence of the menstrual cycle and hormonal contraceptives on training and performance differs between endurance athletes in orienteering compared to team-sport athletes in football and handball. [ABSTRACT FROM AUTHOR]

Background: Blood flow restriction (BFR) resistance training has demonstrated efficacy in promoting strength gains beneficial for rehabilitation. Yet, the distinct functional advantages of BFR strength training using high-load and low-load protocols remain unclear. This study explored the behavioral and neurophysiological mechanisms that explain the differing effects after volume-matched high-load and low-load BFR training. Methods: Twenty-eight healthy participants were randomly assigned to the high-load blood flow restriction (BFR-HL, n = 14) and low-load blood flow restriction (BFR-LL, n = 14) groups. They underwent 3 weeks of BFR training for isometric wrist extension at intensities of 25% or 75% of maximal voluntary contraction (MVC) with matched training volume. Pre- and post-tests included MVC and trapezoidal force-tracking tests (0–75%–0% MVC) with multi-channel surface electromyography (EMG) from the extensor digitorum. Results: The BFR-HL group exhibited a greater strength gain than that of the BFR-LL group after training (BFR_HL: 26.96 ± 16.33% vs. BFR_LL: 11.16 ± 15.34%)(p = 0.020). However, only the BFR-LL group showed improvement in force steadiness for tracking performance in the post-test (p = 0.004), indicated by a smaller normalized change in force fluctuations compared to the BFR-HL group (p = 0.048). After training, the BFR-HL group activated motor units (MUs) with higher recruitment thresholds (p < 0.001) and longer inter-spike intervals (p = 0.002), contrary to the BFR-LL group, who activated MUs with lower recruitment thresholds (p < 0.001) and shorter inter-spike intervals (p < 0.001) during force-tracking. The discharge variability (p < 0.003) and common drive index (p < 0.002) of MUs were consistently reduced with training for the two groups. Conclusions: BFR-HL training led to greater strength gains, while BFR-LL training better improved force precision control due to activation of MUs with lower recruitment thresholds and higher discharge rates. [ABSTRACT FROM AUTHOR]

This study aimed to quantify the influence of the playing surface on workload-related variables (i.e., external load, Rate of perceived exertion (RPE), and mental load) in training sessions with a Spanish professional soccer team. Twenty professional male players from the same soccer team were involved. A total of thirty training sessions related to the preseason period were included. All the players completed training sessions on three playing surfaces: natural turf of poor quality, natural turf of high quality, and third-generation artificial turf. Monitoring during sessions involved assessing internal load (i.e., RPE and mental load) via self-reported questionnaires, and external load using Global Positioning System devices. Linear mixed models showed that RPE was significantly higher on natural turf of high quality than on natural turf of poor quality (p < 0.001). Total distance, relative total distance, the number of accelerations, decelerations, and high metabolic load distance were significantly lower on third-generation artificial turf compared to natural turf of poor quality (p < 0.001) and high quality (p < 0.001). In addition, high-speed running, sprint running distances, and the number of sprints reached higher values on third-generation artificial turf compared to the other two playing surfaces. These findings highlight the need for coaches to consider the type of training surface in soccer to optimize training load planning and prevent injuries. [ABSTRACT FROM AUTHOR]