Identifying Key Training Load and Intensity Indicators in Ice Hockey Using Unsupervised Machine Learning.

To identify key training load (TL) and intensity indicators in ice hockey, practice, and game data were collected using a wearable 200-Hz accelerometer and heart rate (HR) recording throughout a four-week (29 days) competitive period (23 practice sessions and 8 competitive games in 17 elite Danish players (n = 427 observations). Within-individual correlations among accelerometer- (total accelerations [Acctot], accelerations >2 m·s-2 [Acc2], total accelerations [Dectot], decelerations <- 2 m·s-2 [Dec2]), among HR-derived (time >85% maximum HR [t85%HRmax], Edwards' TL and modified training impulse) TL indicators, and between acceleration- and HR-derived TL parameters were large to almost perfect (r = 0.69-0.99). No significant correlations were observed between accelerometer- and HR-derived intensity indicators. Three between- and two within-components were found. The K-means++ cluster analysis revealed five and four clusters for between- and within-loadings, respectively. The least Euclidean distance from their centroid for each cluster was reported by session-duration, Acctot, Dec2, TRIMPMOD, %t85HRmax for between-loadings, whereas session-duration, Acc2, t85HRmax and Dec2/min for within-loadings. Specific TL or intensity variables might be relevant to identify similar between-subject groups (e.g. individual player, playing positions), or temporal patterns (e.g. changes in TL or intensity over time). Our study provides insights about the redundancy associated with the use of multiple TL and intensity variables in ice hockey.

Effect of Training Load Intensification on the Sleep Pattern of Young Soccer Players.

Purpose: The aim of this study was to examine how intensifying training loads over a week affects the sleep patterns of young soccer players on the nights immediately following the intensified training sessions. Methods: Quasi-experimental study. Fifteen young athletes participants of a team engaged in national level competition, underwent two weeks of training with varying load magnitudes-Week 1: low accumulated training load and Week 2: intensified training loads [40% increase in external training load(ETL)]. To characterize the intensification of the workload, the methods PlayerLoad and RPE-Session were employed to measure ETL and internal training load(ITL), respectively. Total sleep time(TST), total time in bed(TTB), sleep efficiency(SE), sleep latency(SL), and wake after sleep onset(WASO) were obtained using actigraphy and daily sleep log. The variables were compared among the days of week (e.g. Monday of week 1 with Monday of week 2, and so forth). Results: Acute training intensification in week 2 led to significant increases in ETL and ITL on Monday and on Wednesday(p < .05), and ETL(p < .05) on Friday on the second week. Improvements in sleep were observed (Tuesday-TST:+80 min, WASO:-29.3 min, SL:-8 min, SE:+9%; Thursday-TST:+86 min, SL:-4 min, SE:+4%; Saturday-TST:+40 min, SL:+1 min) compared to the same day of the previous week. Correlations between ETL and ITL(r = 0.637), ITL and TST(r = 0.572), ITL and SE(r = 0.548) were found. Conclusion: Intensification of training loads results in alterations in sleep variables, notably an elevated TST and SE in the days subsequent to the acute load increment.

Perceptions and use of recovery strategies in water polo players and coaches: a worldwide survey.

The objective of this study was to assess the perceived usefulness, actual use and limitations for the application of recovery strategies among water polo (WP) players and their coaches around the world. A total of 231 WP players and 76 coaches representing all continents, both genders and all levels of competition, completed a freely accessible online survey. This was divided into three sections: sociodemographic data (8 questions), importance of perceived usefulness of recovery strategies (3 questions), and actual use of recovery methods (6 questions). The majority of players and coaches considered recovery strategies as very important (52.4% and 59.2%, respectively) and posttraining session (28.1% and 26.5%) were the most frequently used times. The most selected reasons to justify their use were to reduce the injury risk (30.4% and 26.9%) and the most limitation to the use of recovery strategies were that they are too time-consuming (34.9% and 29%). In the case of the players, stretching were the strategies perceived as most useful and used (12.7% and 18.1%); and in the case of the coaches, it was active recovery (11.2% and 15%). The present study suggests a degree of discrepancy between the scientific literature and the research participants' perceptions and usages of recovery methods. This information may be of interest for coaches and technical staff of WP teams to look for appropriate recovery strategies for the improvement of their players' performance.

Variations in strength-speed-power performance across the season: do true changes occur in elite rugby players?

This study aimed to determine, through the use of a highly sensitive statistical tool, whether real changes in performance were present; and compare the rates of meaningful variations in strength, speed, and power parameters at different time-points during the competitive season in national team rugby players. Thirty-two players were assessed 5 times across the season using the following tests: squat jump and countermovement jump tests; 30-m sprint velocity; and one-repetition maximum (1RM) in the half-squat and bench-press exercises. A repeated-measures analysis of variance was conducted to test for differences between successive time-points. Individual coefficients of variation values were used to set target scores for post-measurements and examine whether changes in performance parameters were greater than the natural test variance, thus providing an indication of whether "true changes" occurred. No significant changes were detected in the vertical jump height, 1RM measures, and sprint velocity and momentum throughout the 11-month period (P > 0.05). True changes occurred much more frequently for strength-power measures than for sprint velocity and momentum. Elite rugby union players did not exhibit significant variations in neuromuscular performance across the competitive period, when a group-based analysis was conducted. However, at the individual level, "true changes" in strength-power-(but not in speed-) related qualities were consistently observed over the competitive season.

Analyzing soccer match sprint distances: A comparison of GPS-based absolute and relative thresholds.

This study compared the most common absolute sprint threshold (> 25.2 km/h) with relative and individualized thresholds (> 70%, > 75%, > 80%, > 85% and > 90% of peak match speed). Twenty elite soccer players, competing in the first division of the Portuguese League, were monitored using GNSS equipment during thirty-four official matches. Peak match speed was retrieved as the individual maximal speed reached during the full season. Distances were registered when speed overcame the absolute and the relative thresholds. Mean ± SD of peak speeds and distances covered were calculated, and Pearson correlation (r) and mean paired differences were performed to analyze relationships and differences between thresholds. The peak match speed was 32.9 ± 1.4 km/h. Correlations between distances covered using the absolute and relative thresholds varied from very strong (> 70%: r = 0.84, p < .001; > 75%: r = 0.89, p < .001; and > 80%: r = 0.88, p < .001), strong (> 85%: r = 0.79, p < .001), to moderate (> 90%: r = 0.59, p < .001). Overall, the > 75% (ES: 0.23 [95% CI: 0.16, 0.31]) and the > 90% (ES: -1.65 [95%CI: -1.85, -1.48]) relative thresholds presented the smallest and largest differences, respectively, with the absolute threshold. Differences were also found when considering the playing positions. While the distances covered by central midfielders were similar between the absolute and > 80% thresholds (-0.03 [-0.16, 0.10]), fullbacks covered largely more distance -1.88 [-2.42 -1.50]) in the absolute threshold than in the > 80% threshold. The distances covered by players varied based on the selected threshold, affecting the distances covered by different playing positions. Being the highest speed threshold within displacements thresholds, the absolute sprint threshold showed greater similarity to lower rather than higher relative thresholds.

The effects of different levels of sports activity on health-related quality of life and lifestyle habits in high school Italian students.

Physical activity (PA) is an important predictor of physical and mental health preventing chronic degenerative diseases. The purpose of this study was to investigate in a group of Italian high school students whether health-related quality of life (HRQoL) and lifestyle habits (diet) are associated with the level of physical activity performed (low, moderate, high). Data were collected from 2819 adolescents (n = 951 males). HRQoL was analyzed using the Italian version of the KIDSCREEN-52. Physical activity level was analyzed using the PAQ-A, while eating habits with KIDMED. Practicing physical activity in general improves HRQoL. Specifically, adolescents practicing moderate or high PA, in single dimensions of HRQoL, showed better mood (p < 0.001), self-perception (p < 0.001), family relationships (p < 0.001), reported a higher perception of socioeconomic status (p < 0.05), relationship with peers (p < 0.001), and social acceptance (p < 0.001). High PA subjects reported increased physical (p < 0.001) and mental health (p < 0.001), increased autonomy (p < 0.001), and school learning (p < 0.001). For lifestyle habits, practicing moderate PA showed higher adherence tox the Mediterranean diet (p < 0.001). Conclusion: Our results highlighted a positive association between the frequency of PA levels, some dimensions of HRQoL, and risk behaviors. These findings demonstrated the protective role of sports not only as a preventive strategy for the onset of chronic degenerative diseases, but also as an educator of healthy lifestyle habits, thus suggesting the importance and need to implement strategies to promote sports practice.

Heart Rate Variability in Professional and Semiprofessional Soccer: A Scoping Review.

In modern soccer, fitness and fatigue monitoring tools tend to be focused on noninvasive, time-efficient and player-friendly measures. Heart rate variability (HRV) has been suggested as an effective method for monitoring training response and readiness to perform. However, there is still a lack of consensus on HRV monitoring when it comes to soccer. Thus, this scoping review aims to map existing evidence on HRV in professional and semiprofessional soccer settings, and to identify knowledge gaps to inform future research directions. A search of databases (PubMed, Scopus, Web of Science, Google Scholar) according to the PRISMA-ScR statement was employed. Studies were screened for eligibility on inclusion criteria: (1) HRV was among the topics discussed in the article; (2) adult professional or semiprofessional soccer players were involved in the study; (3) both male and female participants; (4) no geographical area exclusion; (5) articles published in English; and (6) article full text available. The search of the selected databases revealed 8456 records. The titles and abstracts of all articles were retrieved for screening of eligibility, leaving 30 articles for further consideration. Following screening against set criteria, a total of 25 studies were included in this review, the sample size of which ranged from 6 to 124 participants. The participants in the included studies were professional and semiprofessional soccer players, interviewed clubs staff, and practitioners. Along with other monitoring strategies, morning vagally mediated HRV analysis via (ultra)short-term orthostatic measurements may be an efficient way to assess training adaptations and readiness to perform in professional and semiprofessional soccer players. Further research is required to make definitive recommendations.

Space and players' number constrains the external and internal load demands in youth futsal.

Introduction: The aim of this study was to analyze the effects of space and number of players manipulation on the external and internal load demands of youth futsal athletes. Methods: Forty-two male U17 players (age = 15.62 ± 0.58 years) from three futsal teams participated in the study. In this cross-sectional study that lasted 8-week, the player's sample practiced six futsal tasks (T1-T6) and a futsal game played under the official rules (T7). From T1-T6, two task constraints were manipulated: (i) the number of players and, (ii) the space of play. The WIMU PRO™ Ultra-Wideband (UWB) tracking system was used to measure the external and internal load during the futsal tasks. External load was quantified using kinematic and mechanical variables extracted from positional data and, the internal load was quantified using Heart rate (HR) and rating of perceived exertion (RPE). Repeated measures ANOVA was used for comparison purposes. Results: In general, the results showed high external (total distance, distance 18.1-21, above 21 Km/h, and high intensity acceleration and deceleration, p < 0.001) and internal load (heart rate average and rating of perceived exertion, p < 0.001) in the tasks with low number of players and high area. In relation to the match, the tasks with small relative area per player (GK + 2 vs. 2 + GK and GK + 3 vs. 3 + GK in 20 × 20 m) promoted low external load. Conclusion: It was concluded that increasing the relative area by reducing the number of players involved in the tasks in the form of small-sided games (GK + 2 vs. 2 + GK and GK + 3 vs. 3 + GK), in relation to the futsal game (GK + 4 vs. 4 + GK), can be considered a pedagogical strategy to increase the external and internal load demands of young futsal players.

The physical, technical and tactical demands of on-field training drills in professional Rugby league: a systematic scoping review.

OBJECTIVES: The main objectives of this scoping review were to conduct a systematic search on the physical, technical and tactical demands of rugby league training, consolidate and summarise key findings and identify any existing gaps in knowledge. METHODS: A systematic online search of Scopus, PubMed, MEDLINE and SPORTDiscus was conducted from earliest record to 6 August 2023 and supplemented by manually searching reference lists. The Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) Checklist was followed. Studies were eligible for inclusion if they investigated the physical, technical and/or tactical demands of rugby league training within all levels of competition and included either male or female participants. RESULTS: The initial search yielded 637 papers, 25 of which were included in the review. Of these studies, the majority (n = 19) exclusively examined the physical demands of training, one paper exclusively examined the technical demands of training, five studies included both physical and technical demands, and no studies examined the tactical demands of training. Small-sided games was the most prevalent drill included within investigations examining the physical and technical demands of various rugby league training drills. CONCLUSIONS: The present review was the first to scope peer-reviewed literature on the multifaceted demands (i.e. physical, technical and tactical) demands of rugby league training. It is apparent that this area is under researched, specifically in literature examining the technical and tactical elements of rugby league training.

Of the available literature examining the multifaceted demands of rugby league training, the majority investigated the physical demands, with a peak of four publications in 2012 and 2022 and an average number of one to two publications per year since its introduction (i.e. 2010). There is only a small number of studies available investigating the technical demands of rugby league training.While research has identified the importance of tactics to successful rugby league performance, there has been no investigations on the tactical demands within rugby league training. Accordingly, it is unknown how coaches meet their tactical objectives within training drills and training design to prepare for competition.There is a clear gap in research investigating the technical and tactical demands of rugby league training as well as the absence of team-based training drills included within available studies investigating the physical demands. Accordingly, future investigations should prioritise incorporating these elements within their research design.

A 3-Month Modified Basketball Exercise Program as a Health-Enhancing Sport Activity for Middle-Aged Individuals.

Recreational team sports have received great acceptance lately, in different populations, indicating encouraging results in health-related quality of life. This study examined the efficacy of a 3-month basketball exercise program on selected indices of health (body mass-BM, body fat-BF, blood pressure-BP), functional capacity (flexibility of lower and upper limbs, balance), and physical fitness (maximum strength of lower limbs, trunk and handgrip, aerobic capacity) in middle-aged individuals. Forty middle-aged individuals (males and females; 40-55 years old) were randomly divided into (a) exercise (EG; n = 20) and (b) control groups (CG; n = 20). The EG followed a 3-month modified basketball exercise program (2 times/week; 24 training units), including different basketball drills with and without the ball (dribbling, passing, pivot, stops, etc.), to improve participants' health and physical fitness. Repeated measures ANOVA showed that the EG significantly increased their flexibility (17.23-74.88%; p < 0.001), static balance (44.76-54.69%; p < 0.001), and strength of lower limbs and trunk (11.67-13.13%; p < 0.001), while reducing BP (7.31-12%; p < 0.001), heart rate and RPE (5.30-34.37%; p < 0.001), and time during time-up-and-go test (-10.91%; p < 0.001). Handgrip strength, BM, and BF did not change following the program in the EG (p > 0.05). In the CG, the above variables remained stable. In conclusion, this program may be used to eliminate the detrimental effects of aging on health, functional capacity, and physical fitness parameters.

Internal and External Load Profile during Beach Invasion Sports Match-Play by Electronic Performance and Tracking Systems: A Systematic Review.

Beach variants of popular sports like soccer and handball have grown in participation over the last decade. However, the characterization of the workload demands in beach sports remains limited compared to their indoor equivalents. This systematic review aimed to: (1) characterize internal and external loads during beach invasion sports match-play; (2) identify technologies and metrics used for monitoring; (3) compare the demands of indoor sports; and (4) explore differences by competition level, age, sex, and beach sport. Fifteen studies ultimately met the inclusion criteria. The locomotive volumes averaged 929 ± 269 m (average) and 16.5 ± 3.3 km/h (peak) alongside 368 ± 103 accelerations and 8 ± 4 jumps per session. The impacts approached 700 per session. The heart rates reached 166-192 beats per minute (maximal) eliciting 60-95% intensity. The player load was 12.5 ± 2.9 to 125 ± 30 units. Males showed 10-15% higher external but equivalent internal loads versus females. Earlier studies relied solely on a time-motion analysis, while recent works integrate electronic performance and tracking systems, enabling a more holistic quantification. However, substantial metric intensity zone variability persists. Beach sports entail intermittent high-intensity activity with a lower-intensity recovery. Unstable surface likely explains the heightened internal strain despite moderately lower running volumes than indoor sports. The continued integration of technology together with the standardization of workload intensity zones is needed to inform a beach-specific training prescription.

A 10-week play-based after-school program to improve coordinative abilities and physical fitness capabilities among adolescents: a randomized trial.

The average levels of physical activity in children are below the ideal, which may influence children's health and motor competence levels. Therefore, this study aimed to assess the impact of a 10-week play-based after-school program on 50 twelve-year-old students' anthropometric characteristics (body height and body weight), coordinative abilities (flamingo balance test and T-test agility), and physical fitness (sit and reach, 20-m sprint test, SLJ, CMJ, and handgrip). After baseline assessments, the students were randomly divided into two groups: one participating in a play-based after-school program (experimental group) and the other attending regular PE classes (control group). No differences were noted between the sexes. Analysis revealed baseline differences between groups in body weight, agility T-test, and right-handgrip, with no significant sex differences. Following the intervention, the experimental group demonstrated improvements in the 20-m sprint test (F(1,46) = 11.03, p < 0.01), flamingo balance test (F(1,46) = 9.16, p = 0.004), SLJ (F(1,46) = 5.30, p = 0.03), agility T-test (F(1,46) = 28.30, p < 0.01), and right-handgrip (F(1,46) = 6.59, p < 0.01). In summary, the results suggested that a 10-week play-based after-school program enhances coordinative abilities and physical fitness in 12-year-old children. This underscores the potential advantages of integrating play-based physical activities into schools to promote holistic health and fitness in children.

Effects of a horizontal speed deceleration training programme on measures of physical fitness in youth male handball players.

This study examined the effects of an 8-week horizontal speed deceleration training (HSDT) programme in combination with regular handball-specific training as compared with handball-specific training only in measures of physical fitness in male youth handball players. Thirty-nine players were randomly assigned to either an HSDT group (n = 18; 15.55 ± 0.24 years) or an active-control group (CG; n = 21; 14.59 ± 0.23 years). The results showed significant and large between-group differences at post-test in countermovement jump, change-of-direction speed, and repeated sprint ability (RSA) (all p < 0.01; d = 2.04 and 1.37, 1.39, 1.53, and 1.53 for the CMJ, 505 CoD, RSAbest, RSAaverage, and RSAtotal performances, respectively). The post-hoc-analysis demonstrated significant and large improvements in all measures of physical fitness in the HSDT group (∆2.49% to 16,25%; d = 1.01 to 1,70; all p < 0,01). The CG, however, failed to reach any significant difference in all measures of physical fitness ((∆0.31% to 1.98%; d = 0.15 to 0.22; p = 0.379; p > 0.05). To summarise, an 8-week in-season HSDT programme alongside regular handball-specific training yielded positive effects on various performance measures including jumping ability, CoD speed, and RSA, when compared to handball-specific training alone. These results highlight the potential benefits of integrating HSDT into the training regimen of youth handball athletes during the competitive season.

Comparison of Australian Football League Women's athletes match day energy and nutrient intake to recommendations.

AIMS: This cross-sectional observational study quantified Australian Football League Women's athletes' match volume, and compared match-day dietary intakes against recommendations. METHODS: Self-report, direct observation, and fluid measurements determined dietary intake (n = 17, 25 ± 4.5 years, 22.8 ± 1.8 kg/m2) on five home match days (early or late starting). Global positioning system software captured match volume. Linear mixed effects models evaluated differences in early versus late match volume and nutrient intakes. Data are presented as mean ± standard deviation. RESULTS: Athletes covered 6712 ± 622 m during matches, with similar numbers of very high-intensity running efforts over equal distances in early and late matches (early vs. late efforts [no.]: 8.5 ± 4.9 vs. 9.5 ± 5.5; distance [m]: 203 ± 127 vs. 212 ± 113). Across all match days, 71% (n = 12) of athletes met their predicted daily energy requirements. However, 82% (n = 14) failed to meet minimum daily carbohydrate recommendations; intake was lower on early compared with late match days (4.7 g/day vs. 5.4 g/kg/day, p = 0.027). On average, no athletes met carbohydrate recommendations in the 2 h prior to a match and only 24% (n = 4) met recommendations during matches. All athletes met post-match carbohydrate and protein requirements. CONCLUSION: Athletes cover large distances during games with frequent bursts of high-intensity running. However, they do not adjust their intake to meet the energy demands of competition, with inadequate fuelling prior to and during matches. These findings emphasise the need for greater athlete education and dietary support to maximise strategic fuelling to optimise athletic performance.

Energy System Contributions in Repeated Sprint Tests: Protocol and Sex Comparison.

The aim of this study was to investigate the energy system contributions to different repeated sprint protocols and also to determine sex-related differences in these contributions. Sixteen men and fourteen women team sport athletes randomly performed two cycling repeated sprint protocols with the same total duration (10 x 6 s and 6 x 10 s). Relative peak power (RPP), relative mean power (RMP), performance decrement (PD), oxygen uptake (VO2), blood lactate (LA), heart rate (HR) and ratings of perceived exertion (RPEs) were measured. The contributions of energy systems were calculated from oxygen consumption and lactate values during rest, exercise and recovery phases based on mathematical methods. Findings indicate that men had higher RPP and RMP. RPP did not differ according to protocols, while RMP was higher in the 10 x 6 s protocol. The sex effect in PD was similar; however, it was higher in the 6 x 10 s protocol. The effects of protocols on the maximum HR and LA were similar; however, the 6 x 10 s protocol resulted in higher RPEs. In both protocols women had higher ATP-PCr and men had higher glycolytic system contribution with similar oxidative system contribution. In addition, the 10 x 6 s protocol had higher ATP-PCr system contribution and the 6 x 10 s protocol had higher glycolytic system and oxidative system contributions. In conclusion, the contribution of energy systems, physiological and performance variables showed variations according to sex and different protocols.

Zinc transporters expression profile in professional handball players supplemented with zinc.

INTRODUCTION: Zinc (Zn) deficiency has been described not only on general human health but also within the sports context -as negatively affecting performance-. Thus, Zn status assessment is of great interest for athletes, especially in order to correct deficiency states of this mineral. OBJECTIVE: The overall objective of this work was to assess Zn status in professional handball players during the competitive period (through plasma levels, dietary intake and gene expression of the Zn transporters), as well as to determine the effect of Zn supplementation. METHODS: A total of twenty-two participants were recruited, -twelve belonged to the Control Group (CG) and ten male handball players comprised the experimental group (ATH-G)-, being monitored over a 2-month period with 2 evaluation moments: baseline (i.e., initial conditions) and follow-up (i.e., after 8 weeks of training and competition). Zn intake, plasma Zn levels, and gene expression of Zn transporters were obtained. RESULTS: Plasma Zn levels were higher in ATH-G than in CG at the end of Zn intervention (p ≤ 0.010). Moreover, differences in the gene expression profile of Zn transporters were observed in ATH-G -with the down-regulation of several Zn transporters-, compared to the CG at baseline (p ≤ 0.05). Likewise, differences in the Zn transporters expression were observed in ATH-G at 8 weeks (all, p ≤ 0.001) -with ZnT2, ZnT5, ZIP3, ZIP5, ZIP11, ZIP13 and ZIP14 transporters being up-regulated-. CONCLUSION: Handball players seemed to have different nutritional needs for Zn, with differences in the gene expression of Zn transporters compared to controls. Zn intervention in our athletes may have influenced the expression of Zn transporters, indicating a potential increase in Zn transporters expression to mobilize Zn at the cellular level at 8 weeks of Zn intervention.

Plyometric Jump Training Effects on Maximal Strength in Soccer Players: A Systematic Review with Meta-analysis of Randomized-Controlled Studies.

BACKGROUND: Maximal strength may contribute to soccer players' performance. Several resistance training modalities offer the potential to improve maximal strength. During recent years, a large number of plyometric jump training (PJT) studies showed evidence for maximal strength improvements in soccer players. However, a comprehensive summary of the available data is lacking. OBJECTIVE: To examine the effects of PJT compared with active, passive or intervention controls on the maximal strength of soccer players, irrespective of age, sex or competitive level. METHODS: To perform a systematic review with meta-analysis following PRISMA 2020. Three electronic databases (PubMed, Web of Science, and SCOPUS) were systematically searched. Studies published from inception until March 2023 were included. A PICOS approach was used to rate studies for eligibility. The PEDro scale was used to assess risk of bias. Meta-analyses were performed using the DerSimonian and Laird random-effects model if ≥ 3 studies were available. Moderator and sensitivity analyses were performed, and meta-regression was conducted when ≥ 10 studies were available for a given comparison. We rated the certainty of evidence using GRADE. RESULTS: The search identified 13,029 documents, and from these 30 studies were eligible for the systematic review, and 27 for the meta-analyses. Overall, 1,274 soccer players aged 10.7-25.0 years participated in the included studies. Only one study recruited females. The PJT interventions lasted between 5 and 40 weeks (median = 8 weeks), with 1-3 weekly sessions. Compared to controls, PJT improved maximal dynamic strength (18 studies, 632 participants [7 females], aged 12.7-24.5 y; effect size [ES] = 0.43, 95% confidence interval [CI] = 0.08-0.78, p = 0.017, impact of statistical heterogeneity [I2] = 77.9%), isometric strength (7 studies; 245 participants, males, aged 11.1-22.5 y; ES = 0.58, 95% CI = 0.28-0.87, p < 0.001, I2 = 17.7%), and isokinetic peak torque (5 studies; 183 participants, males, aged 12.6-25.0 y; ES = 0.51, 95% CI = 0.22-0.80, p = 0.001, I2 = 0.0%). The PJT-induced maximal dynamic strength changes were independent of participants' age (median = 18.0 y), weeks of intervention (median = 8 weeks), and total number of training sessions (median = 16 sessions). The certainty of evidence was considered low to very low for the main analyses. CONCLUSIONS: Interventions involving PJT are more effective to improve maximal strength in soccer players compared to control conditions involving traditional sport-specific training. Trial Registration The trial registration protocol was published on the Open Science Framework (OSF) platform in December 2022, with the following links to the project ( https://osf.io/rpxjk ) and to the registration ( https://osf.io/3ruyj ).

Return to athletics after total knee arthroplasty: a survey study of 784 recreational athletes across 12 sports.

BACKGROUND: Postoperative return to recreational activity is a common concern among the increasingly active total knee arthroplasty (TKA) patient population, though there is a paucity of research characterizing sport-specific return and function. This study aimed to assess participation level, postoperative return to activity, sport function, and limitations for recreational athletes undergoing TKA. METHODS: A survey of recreational sports participation among primary, elective TKA patients from a single academic center between June 2011 and January 2022 was conducted. Of the 10,777 surveys administered, responses were received from 1,063 (9.9%) patients, among whom 784 indicated being active in cycling (273 [34.8%]), running (33 [4.2%]), jogging (68 [8.7%]), swimming (228 [29.1%]), tennis (63 [8.0%]), skiing (55 [7.0%]), or high-impact team sports (64 [8.2%]) between two years preoperatively and time of survey administration, and were included for analyses. RESULTS: Cycling (62.3% at two years preoperatively vs. 59.0% at latest follow-up) and swimming (62.7% at two years preoperatively vs. 63.6% at latest follow-up) demonstrated the most favorable participation rate changes, while running (84.0% at two years preoperatively vs. 48.5% at latest follow-up) and skiing (72.7% at two years preoperatively vs. 45.5% at latest follow-up) demonstrated the least favorable participation rate changes. The majority of respondents were "satisfied" or "very satisfied" with their return across all sports, though dissatisfaction was highest among runners and joggers. For cycling, running, jogging, and swimming, respondents most commonly reported no change in speed or distance capacity, though among these cyclists reported the highest rates of improved speed and distance. The majority of returning skiers reported improved balance, form, and ability to put on skis. CONCLUSION: Return to sport is feasible following TKA with high satisfaction. Swimming and cycling represent manageable postoperative activities with high return-rates, while runners and joggers face increased difficulty returning to equal or better activity levels. Patients should receive individualized, sports-specific counseling regarding their expected postoperative course based on their goals of treatment.

Does Total Playing Time Affect the Neuromuscular, Physiological, and Subjective Recovery of Futsal Players during a Congested Period?

The aims of this study were to analyze the effects of a congested period (three games in four days) on countermovement (CMJ) jump-landing metrics, heart rate variability (HRV), and total recovery quality (TQR) score in under-19 male futsal players, and to detect the differences between those who played for more minutes (HIGHMIN) and less minutes (LOWMIN). Fourteen youth futsal players (age: 17.5 ± 0.5 years; body mass: 70.2 ± 8.5 kg; height: 1.80 ± 0.1 m) participated. HRV, TQR questionnaire, and CMJ metrics (i.e., CMJ height, relative peak power (PPREL), eccentric and concentric impulse, braking time, and time to peak force) were registered. A linear mixed model and effect sizes (ESs) were used to assess the differences between groups and days. Considering the total sample, a significant decrease was found in the PPREL and TQR score (p = 0.001-0.013 and ES = 0.28-0.99) on Days 2, 3, and 4 when compared to Day 1. HIGHMIN group presented a significant decrease in PPREL on Day 3 (p = 0.004; ES: 0.62; 95% CI: 0.39-2.65) when compared to Day 1, and in the TRQ score on Day 3 (p = 0.002; ES: 1.98; 95% CI: 0.18-2.46) and 4 (p = 0.003; ES: 2.25; 95% CI: 0.52-3.38) when compared to Day 1. Non-significant differences were found for the rest of the metrics and in the group LOWMIN. In summary, neuromuscular performance (i.e., CMJ PPREL) and subjective recovery were impaired in players with higher playing minutes during a match-congested period when compared to those with less on-court time.

Assessing criterion and longitudinal validity of submaximal heart rate indices as measures of cardiorespiratory fitness: A preliminary study in football.

OBJECTIVES: To evaluate the criterion and longitudinal validity of field- and laboratory-derived heart rate (HR) indices of resting and submaximal fitness tests (SMFTs) as measures of cardiorespiratory fitness. DESIGN: Observational, repeated measures. METHODS: Twenty-nine semi-professional footballers participated. Laboratory assessments took place at the start and end of a preseason training period, whereby resting, SMFT HR-derived indices, and criterion measures of cardiorespiratory fitness (running economy [RE], maximal oxygen uptake [V̇O2 max] and aerobic speed [MAS]) were collected. Throughout this training period, two field-based SMFT protocols, prescribed at different intensities, were administered weekly. Individual slopes were calculated from the analysis of within-athlete change scores. Associations between laboratory and field measures were assessed via Pearson's correlation coefficient (r) and linear regression models. RESULTS: Relationships between SMFT HR-derived indices from laboratory and field were very-large for exercise HR (r = 0.74 to 0.87) and moderate to very-large for HR recovery (0.43 to 0.76). Moderate to very-large inverse relationships were observed between exercise HR and HR recovery with V̇O2 max and MAS (-0.41 to -0.78), whereas resting HR showed no substantial relationships. Changes in exercise HR showed large and very-large inverse correlations with preseason changes in V̇O2 max (-0.54 to -0.60) and MAS (-0.64 to -0.83). Relationships between changes in HR recovery and maximal cardiorespiratory criterion measures were moderate to large (-0.32 to -0.63). CONCLUSION: SMFT exercise HR is a valid proxy measure of cardiorespiratory fitness irrespective of test setting, whereas the validity of HRR remains elusive and appears to vary between exercise intensities.