The Accuracy of a Low-Cost GPS System during Football-Specific Movements.

An affordable player monitoring solution could make the evaluation of external loading more accessible across multiple levels of football (soccer). The present study aimed to determine the accuracy of a newly designed and low-cost Global Positioning System (GPS) whilst performing match-specific movement patterns. Sixteen professional male football players (24 ± 3 years) were assigned a GPS device (TT01, Tracktics GmbH, Hofheim, Germany) and completed two experimental trials. In each trial, a continuous protocol including seven movements (sideways cornering, diagonal cornering, accelerating, decelerating, backwards jogging, shuttle running, and skipping) adding up to 500 m, was completed. Time-motion data was compared with criterion distance and velocity (photo-cell timing gates and radar). Validity was assessed through the standard error of the estimate (SEE) and reliability through the coefficient of variation (CV; both with 95% confidence limits). For the total distance covered during the protocol, the system was found to be valid (SEE = 3.1% [2.2; 5.8]) and reliable (intra-device CV = 2.0% [1.2; 7.6]). Similar results were found for velocity (SEE = 3.4% [2.6; 4.8], CV = 4.7% [3.2; 8.5]). In conclusion, the present GPS system, a low-cost solution, was found to be a valid and reliable tool for measuring physical loading during football-specific movements.

Understanding the presence of mental fatigue in English academy soccer players.

Research has demonstrated that induced mental fatigue impairs soccer-specific technical, tactical and physical performance in soccer players. The findings are limited by the lack of elite players and low ecological validity of the tasks used to induce mental fatigue, which do not resemble the cognitive demands of soccer. The current study collected survey data from English academy soccer players (n = 256; age groups - U14 - U23), with questions comprising of five themes (descriptors of physical and mental fatigue, travel, education, match-play and fixture congestion). The survey consisted of multiple choice responses, checkboxes and blinded/unblinded (for duration based questions) 0-100 arbitrary unit (AU) slider scales. Listening to music (81.6% of players), using social media (58.3%) and watching videos (34.3%) were the most common pre-match activities. Pre-match subjective mental fatigue was low (18.7±18.8 AU), and most frequently reported at the end of a match (47±26 AU) and remained elevated 24-hours post-match (36±27 AU). Travel (29±24 AU), fixture congestion (44±25 AU) and education (30±26 AU) demonstrated a low to moderate presence of subjective mental fatigue. These findings provide an overview of activities performed by English academy soccer players pre-match, and demonstrate that mental fatigue is experienced as a result of match-play.

A Longitudinal Analysis of the Executive Functions in High-Level Soccer Players.

INTRODUCTION: Assessments of executive functions (EFs) with varying levels of perceptual information or action fidelity are common talent-diagnostic tools in soccer, yet their validity still has to be established. Therefore, a longitudinal development of EFs in high-level players to understand their relationship with increased exposure to training is required. METHODS: A total of 304 high-performing male youth soccer players (10-21 years old) in Germany were assessed across three seasons on various sport-specific and non-sport-specific cognitive functioning assessments. RESULTS: The posterior means (90% highest posterior density) of random slopes indicated that both abilities predominantly developed between 10 and 15 years of age. A plateau was apparent for domain-specific abilities during adolescence, whereas domain-generic abilities improved into young adulthood. CONCLUSION: The developmental trajectories of soccer players' EFs follow the general populations' despite long-term exposure to soccer-specific training and game play. This brings into question the relationship between high-level experience and EFs and renders including EFs in talent identification questionable.

Submaximal Markers of Fatigue and Overreaching; Implications for Monitoring Athletes.

The regular monitoring of athletes is important to fine-tune training and detect early symptoms of overreaching. Therefore the aim of this study was to determine if a noninvasive submaximal running test could reflect a state of overreaching. 14 trained runners completed a noninvasive Lamberts Submaximal Running Test, one week before and 2 days after finishing an ultramarathon, and delayed onset of muscle soreness and the daily analysis of life demands for athletes questionnaire were also captured. After the ultramarathon, submaximal heart rate was lower at 70% (-3 beats) and 85% of peak treadmill running speed (P<0.01). Ratings of perceived exertion were higher at 60% (2 units) and 85% (one unit) of peak treadmill running speed, while 60-second heart rate recovery was significantly faster (7 beats, P<0.001). Delayed Onset of Muscle Soreness scores and the number of symptoms of stress (Daily Analysis of Life Demands for Athletes) were also higher after the ultramarathon (P<0.01). The current study shows that the Lamberts Submaximal Running Test is able to reflect early symptoms of overreaching. Responses to acute fatigue and overreaching were characterized by counterintuitive responses, such as lower submaximal heart rates and faster heart rate recovery, while ratings of perceived exertion were higher.

Individual Patterns in Blood-Borne Indicators of Fatigue-Trait or Chance.

Julian, R, Meyer, T, Fullagar, HHK, Skorski, S, Pfeiffer, M, Kellmann, M, Ferrauti, A, and Hecksteden, A. Individual patterns in blood-borne indicators of fatigue-trait or chance. J Strength Cond Res 31(3): 608-619, 2017-Blood-borne markers of fatigue such as creatine kinase (CK) and urea (U) are widely used to fine-tune training recommendations. However, predictive accuracy is low. A possible explanation for this dissatisfactory characteristic is the propensity of athletes to react to different patterns of fatigue indicators (e.g., predominantly muscular [CK] or metabolic [U]). The aim of the present trial was to explore this hypothesis by using repetitive fatigue-recovery cycles. A total of 22 elite junior swimmers and triathletes (18 ± 3 years) were monitored for 9 weeks throughout 2 training phases (low-intensity, high-volume [LIHV] and high-intensity, low-volume [HILV] phases). Blood samples were collected each Monday (recovered) and Friday (fatigued) morning. From measured values of CK, U, free-testosterone (FT), and cortisol (C) as determined in the rested and fatigued state, respectively, Monday-Friday differences (Δ) were calculated and classified by magnitude before calculation of ratios (ΔCK/ΔU and ΔFT/ΔC). Coefficient of variation (CV) was calculated as group-based estimates of reproducibility. Linear mixed modeling was used to differentiate inter- and intraindividual variability. Consistency of patterns was analyzed by comparing with threshold values (<0.9 or >1.1 for all weeks). Reproducibility was very low for fatigue-induced changes (CV ≥ 100%) with interindividual variation accounting for 45-60% of overall variability. Case-wise analysis indicated consistent ΔCK/ΔU patterns for 7 individuals in LIHV and 7 in HILV; 5 responded consistently throughout. For ΔFT/ΔC the number of consistent patterns was 2 in LIHV and 3 in HILV. These findings highlight the potential value of an individualized and multivariate approach in the assessment of fatigue.

Are "classical" tests of repeated-sprint ability in football externally valid? A new approach to determine in-game sprinting behaviour in elite football players.

The aim of this study was to investigate the occurrence of repeated sprinting bouts in elite football. Furthermore, the construct validity of current tests assessing repeated-sprint ability (RSA) was analysed using information of sprinting sequences as they actually occurred during match-play. Sprinting behaviour in official competition was analysed for 19 games of the German national team between August 2012 and June 2014. A sprinting threshold was individually calculated based on the peak velocity reached during in-game sprinting. Players performed 17.2 ± 3.9 sprints per game and during the entire 19 games a total of 35 bouts of repeated sprinting (a minimum of three consecutive sprints with a recovery duration <30 s separating efforts). This averages one bout of repeated sprinting per player every 463 min. No general decrement in maximal sprinting speed was observed during bouts with up to five consecutive sprints. Results of the present study question the importance of RSA as it is classically defined. They indicate that shorter accelerations are more important in game-specific situations which do not reach speeds necessary to qualify them as sprints. The construct validity of classic tests of RSA in football is not supported by these observations.

Impaired sleep and recovery after night matches in elite football players.

Despite the perceived importance of sleep for elite footballers, descriptions of the duration and quality of sleep, especially following match play, are limited. Moreover, recovery responses following sleep loss remain unclear. Accordingly, the present study examined the subjective sleep and recovery responses of elite footballers across training days (TD) and both day and night matches (DM and NM). Sixteen top division European players from three clubs completed a subjective online questionnaire twice a day for 21 days during the season. Subjective recall of sleep variables (duration, onset latency, time of wake/sleep, wake episode duration), a range of perceptual variables related to recovery, mood, performance and internal training loads and non-exercise stressors were collected. Players reported significantly reduced sleep durations for NM compared to DM (-157 min) and TD (-181 min). In addition, sleep restfulness (SR; arbitrary scale 1 = very restful, 5 = not at all restful) and perceived recovery (PR; acute recovery and stress scale 0 = not recovered at all, 6 = fully recovered) were significantly poorer following NM than both TD (SR: +2.0, PR: -2.6), and DM (SR: +1.5; PR: -1.5). These results suggest that reduced sleep quantity and quality and reduced PR are mainly evident following NM in elite players.

The effect of forced even pacing and an opponent on end-spurt behaviour in freestyle pool swimming.

To investigate the effect of forced even pacing through virtual pacing assistance and an opponent in a competitive setting on end-spurt behaviour in freestyle swimmers, including related physiological underpinnings. Twenty-seven competitive swimmers and triathletes were recruited. There were four 1500 m freestyle trials: (i) familiarisation time trial, (ii) self-paced time trial (STT), (iii) head-to-head competition time trial (CTT) and (iv) forced even pacing through virtual pacing assistance time trial (FET). Eventually, 12 swimmers met the criteria for the CTT and FET to be included in the analysis. Changes in end-spurt behaviour, finishing time and physiological parameters (lactate, cortisol, noradrenaline and heart rate) were analysed using a linear mixed model with fixed effects for trials and a random effect for swimmer identity. A separate linear model was computed for competition outcome. The end-spurt for each race was determined by means of an end-spurt indicator (ESI; ESI > 0 greater end-spurt). Swimmers demonstrated a significantly greater ESI in FET (+2.6; p < 0.001) and CTT (+1.4; p = 0.022) compared to STT. Blood lactate concentration in FET (+1.0 mmol L-1; p < 0.001) and CTT (+1.6 mmol L-1; p < 0.001) was significantly higher than in STT. Winners had a significantly greater ESI than losers in CTT (+1.6 and p = 0.005). Swimmers utilised a greater end-spurt through metabolically optimal forced even pacing by virtual pacing assistance and in a head-to-head competition due a larger mobilisation of anaerobic reserves as indicated by greater blood lactate concentrations. Winners had a significantly greater end-spurt than losers despite similar metabolic disturbances.

Survey of the current practices of German football academies towards biological maturation assessment.

OBJECTIVES: This study aimed to examine the importance assigned to assessing and considering biological maturation in thematic areas of player development and provide an overview of current practices in German football academies regarding its consideration in training and competition. METHODS: An online survey was sent to 56 elite German football academies. A total of 46 responded to the questionnaire (82% response rate). Six participants provided incomplete information resulting in a total of 40 completed surveys in the period from March to May 2022. RESULTS: Only 20 of participants regularly carried out maturation assessments, despite 95% recognizing its importance for load management, 90% for player development, and 85% for injury prevention. There was no consistent approach to modifying training and competition formats based on maturity status, with a primary focus on gym-based sessions for load management. CONCLUSION: The survey results highlight limited implementation of maturation assessment and training modification based on maturity status in German elite youth football academies. Despite recognizing the importance of load monitoring, reporting to parents, and long-term player development in considering biological maturation, practices are not widespread. The predominant use of the maturity offset method suggests an opportunity to improve accuracy by exploring alternative measurement methods and increasing assessment frequency. Moreover, a lack of established procedures for incorporating maturity status into training and competition exists, hindering comprehensive consideration of biological maturation and injury risk prevention. Further research is needed to understand the reasons for inconsistent approaches in maturation assessment and load modification during training and competition.

Psychophysiological Responses to a Preseason Training Camp in High-Level Youth Soccer Players.

PURPOSE: This study aimed to examine the responsiveness of commonly used measurement instruments to a short training camp by examining the time course of psychophysiological responses in high-level youth soccer players. METHODS: Monitoring was carried out in 14 U15 male soccer players of 1 professional youth academy. Players provided data 3 days prior to (D - 3), during (D2-D4), and 1 (D + 1) and 4 days (D + 4) after the camp: 4 items for the Short Recovery and Stress Scale (SRSS), a countermovement jump (CMJ), and a submaximal run to assess exercise heart rate and heart-rate recovery. Training load during the camp followed an alternating low-high pattern, with lower training loads on D1 and D3 and higher training loads on D2 and D4. RESULTS: Changes in SRSS physical performance capability, emotional balance, overall recovery, muscular stress, and overall stress were small to moderate on D3 and moderate to large on D + 1, while changes were trivial on D + 4. Some CMJ parameters related to the eccentric phase were slightly improved on D3, and these parameters were slightly impaired on D4. Changes in CMJ parameters were trivial on D + 1 and D + 4. After a moderate decrease in exercise heart rate on D3, there was a small decrease on D + 4 and a moderate increase in heart-rate recovery. CONCLUSION: Measurement instruments such as the SRSS and submaximal runs can be used to monitor acute psychophysiological responses to load, while the CMJ may provide little insight during periods of intensified training load.

Individualised reference ranges for markers of muscle recovery assessment in soccer.

Recently an individualisation algorithm has been developed and shown to significantly improve the diagnostic accuracy of creatine kinase (CK) and urea in endurance sports and Badminton. In this study, the applicability and benefit of this algorithm was evaluated using repeated measures data from 161 professional German soccer players monitored during the 2015-2017 seasons. Venous blood samples were collected after a day off (recovered state) and after a minimum of two strenuous training sessions within 48 h (non-recovered state) and analysed for CK and urea. Group-based reference ranges were derived from that same dataset to ensure the best possible reference for comparison. A z-test was conducted to analyse differences in error rates between individualised and group-based classifications. CK values for the individualised approach showed significantly lower error rates in the assessment of muscle recovery compared to both a population-based (p < .001; z-value: -17.01; test-pass error rate: 21 vs. 67%; test-fail: 19 vs. 64%) and a group-based cut-off (p < .001; z-value: -15.29; test-pass error rate: 65%; test-fail: 67%). It could be concluded that the assessment of muscle recovery in soccer using individualised interpretations of blood-borne markers may offer higher diagnostic accuracy than a population-based and a sample-specific group-based approach.HighlightsAssessing muscle recovery via CK using individualised ranges seems to offer a higher diagnostic accuracy than a sample-specific group-based analysis.Using an individualised algorithm seems to be a promising approach to overcome diagnostic problems arising from large inter- and intraindividual variability in blood parameters as it significantly improved the diagnostic accuracy of CK as a recovery marker.As recovery assessment in elite soccer ultimately aims at the accurate detection of differences in the individual player this algorithm seems to offer coaches and sport scientists a more sensitive approach compared to group-specific evaluations.

Intensity control in swim training by means of the individual anaerobic threshold.

This study aimed at evaluating the homogeneity of physiological responses during swim training bouts with intensities prescribed by reference to the individual anaerobic threshold (IAT). Eighteen competitive front crawl swimmers (female 5, male 13, 10 long-distance, and 8 short-distance swimmers [LDSs, SDSs], age: 17 ± 1.7 years, training history: 7.0 ± 2.8 years, training volume per week: 35 ± 5.7 km) performed an incremental swimming test to determine the IAT. Within a maximum of 3 weeks, 4 training programs were conducted: 20 × 100-m low-intensity endurance training (EN(low), 97% IAT), 5 × 400-m high-intensity endurance training (EN(high), 101% IAT), 5 × 200 m (IT1, 105% IAT), and 10 × 100 m (IT2, 108% IAT) intensive interval training. Blood lactate concentrations (bLa) were determined during each training session. The results are given as median (25th and 75th percentiles). During EN(low) and EN(high), the mean bLas were 1.8 mmol·L(-1) (1.3/3.0 mmol·L(-1)) and 4.4 mmol·L(-1) (3.9/6.4 mmol·L(-1)). The bLas were higher during both IT programs: IT1, 6.3 mmol·L(-1) (5.6/7.2 mmol·L(-1)); IT2, 5.8 mmol·L(-1) (5.0/6.5 mmol·L(-1)). The bLas of most individuals were close to the median values (±2.4 mmol·L(-1)). However, in each of the training programs, some subjects showed bLa values that were clearly above (3-7 mmol·L(-1) higher). In particular, SDSs reached higher bLas at the same intensity compared with LDSs. It is concluded that intensity prescriptions by means of IAT seem to elicit an expected metabolic response in approximately 85% of swim training sessions. The observed average bLa is in the range of those recommended in the scientific literature.

Are Measurement Instruments Responsive to Assess Acute Responses to Load in High-Level Youth Soccer Players?

Purpose: The aim of this study was to assess the short-term responsiveness of measurement instruments aiming at quantifying the acute psycho-physiological response to load in high-level adolescent soccer players. Methods: Data were collected from 16 high-level male youth soccer players from the Under 15 age group. Players were assessed on two occasions during the week: after 2 days of load accumulation ("high load") and after at least 48 h of rest. Measurements consisted of the Short Recovery and Stress Scale (SRSS), a countermovement jump (CMJ) and a sub-maximal run to assess exercise heart-rate (HRex) and heart-rate recovery (HRR60s). Training load was quantified using total distance and high-speed running distance to express external and sRPE training load to express internal load. It was expected that good instruments can distinguish reliably between high load and rest. Results: Odd ratios (0.74-1.73) of rating one unit higher or lower were very low for athlete-reported ratings of stress and recovery of the SRSS. Standardized mean high load vs. rest differences for CMJ parameters were trivial to small (-0.31 to 0.34). The degree of evidence against the null hypothesis that changes are interchangeable ranged from p = 0.04 to p = 0.83. Moderate changes were observed for HRex (-0.62; 90% Cl -0.78 to -0.47; p = 3.24 × 10-9), while small changes were evident for HRR60s (0.45; 90% Cl 0.08-0.80; p = 0.04). Only small to moderate repeated-measures correlations were found between the accumulation of load and acute responses across all measurement instruments. The strongest relationships were observed between HRex and total distance (rm-r = -0.48; 90% Cl -0.76 to -0.25). Conclusion: Results suggest that most of the investigated measurement instruments to assess acute psycho-physiological responses in adolescent soccer players have limited short-term responsiveness. This questions their potential usefulness to detect meaningful changes and manage subsequent training load and program adequate recovery.

Understanding the Presence of Mental Fatigue in Elite Female Football.

Purpose: Previous research investigating the impact of induced mental fatigue in football (soccer) has demonstrated associated performance decrements in physical, technical, tactical and decision-making performance. A common limitation amongst this research is the protocols used to induce mental fatigue which provides low ecological validity, and the inclusion of recreational or sub-elite players. Therefore, understanding the presence of mental fatigue in elite football can provide insight into protocols with greater ecological validity. Methods: The current study used focus groups with 10 elite female football players, focusing on five topics (travel, fixture congestion, receiving tactical information, pre-match routine and pressure to win) related to the perceived causes of mental fatigue in elite football (directed by anecdotal quotes in elite football and research-based theories). Results: Several themes emerged from the data; travel fatigue, inability to switch off from football, fatigue experienced following team meetings, use of pre-match music and internal pressure to succeed. Conclusion: These findings present practical recommendations to reduce mental fatigue in elite football settings, such as considering the timing, content and duration of team meetings, providing players with free time/rest where possible, and considering the modality of coaching instructions during matches.

Analysis of end-spurt behaviour in elite 800-m and 1500-m freestyle swimming.

To analyse the influence of distance, time point of competition, round and finishing position on end-spurt behaviour in swimming. Race results in 800-m and 1500-m freestyle swimming from the last 8 World Championships and 5 Olympic Games (1998-2016) including 1433 races and 528 swimmers were obtained. The end-spurt for each race was determined by means of an End-Spurt Indicator (ESI). The ESI was calculated by dividing the difference between the swim velocity of the last lap (SVLL) and the mean swim velocity of the middle part of the race (SVMP) by the respective individual standard deviation of SVMP. Subsequently, ESI was used as a dependent variable and influences were analysed using a linear mixed model with fixed effects for distance, time point of competition, round and finishing position. An end-spurt was evident in most swims for both race distances. The mean change in swim velocity between the middle part of the race and the last lap was 0.06 ± 0.02 m/s (1.2 ± 0.2 s) in the 800-m and 0.07 ± 0.02 m/s (1.5 ± 0.2 s) in the 1500-m. The finishing position within a race significantly affected the ESI (P < .001, t = 7.28). Specifically, when analysing finals only, ESI was significantly greater in medallists (5.76; quantile: 3.61 and 8.06) compared to non-medallists (4.06; quantile: 1.83 and 6.82; P = .001). The between-subject standard deviation was 1.66 (Cl: 1.42-1.97) with a relative variance component of 23%, while 77% of ESI variance remained unexplained. This is the first study using a newly developed indicator of end-spurt behaviour demonstrating that particularly medallists have a more pronounced end-spurt compared to non-medallists.

The effect of stroboscopic vision on performance in a football specific assessment.

Purpose: This study aimed to investigate how restricted visual feedback affects performance in a football-specific skills assessment that incorporates the coupling of football a-specific perceptual information with football-specific motor actions. Methods: The Footbonaut is a 14x14m cage equipped with 8 ball dispensers and 64 targets measuring passing accuracy and time to complete each pass. Eighty-four amateur male participants (19.5 ± 5.4 years old; 13.1 ± 6.0 years experience) completed two sessions under two different visual conditions: stroboscopic and normal vision. Results: A linear regression revealed that performance under normal conditions was significantly associated (p < 0.001) with the performance decrement under stroboscopic vision conditions. Players were then subdivided into skilled (S; top 25%) and less-skilled (LS; bottom 25%) groups. Restricting visual feedback impacted the average time required to complete the passes in both S and LS groups equally (S: +0.18 s; LS: + 0.12 s; p = 0.385), yet S athletes' accuracy (-11.1%) was more heavily reduced under restricted visual conditions compared to their Normal condition; whereas the LS athletes' accuracy remained relatively unchanged (-1.9%). Conclusion: Therefore, stroboscopic vision may be used to induce performance errors during practice to stimulate larger training effects, particularly in more skilled players.

Menstrual cycle phase and elite female soccer match-play: influence on various physical performance outputs.

INTRODUCTION: The aim of the study was to investigate whether menstrual cycle phases influence the physical performance during soccer match-play. METHODS: Fifteen elite female soccer players, with physiologically normal menstrual cycles, competed in matches over a four-month period. Physical performance was assessed via GPS and expressed as meters per minute, and separated into four individualised thresholds (low, high, very high and sprinting). Seventy-six complete individual match observations, 36 from the follicular and 40 from the luteal phase were recorded. The differences in physical match performance parameters between the cycle phases were evaluated using a mixed linear model. RESULTS: The results of the current study indicate that very high-intensity running distance was significantly greater during the luteal phase compared to the follicular phase (5.90 ± 2.16 m.min-1 vs. 6.64 ± 2.72 m.min-1; p = 0.02). However, this finding was accompanied by large variations across matches (CV = 39.5%). CONCLUSIONS: Overall, the results suggest that the menstrual cycle phase does not influence match physical performance of female soccer players to a significant degree. Therefore, at present, interventions or other methods of coping with menstrual cycle phase do not seem necessary on a group/team level to maximise competitive physical performance.

Practitioner, Coach, and Athlete Perceptions of Evidence-Based Practice in Professional Sport in Australia.

PURPOSE: To examine practitioners', coaches', and athletes' perceptions of evidence-based practice (EBP) in professional sport in Australia. METHODS: One hundred thirty-eight participants (practitioners n = 67, coaches n = 39, and athletes n = 32) in various professional sports in Australia each completed a group-specific online questionnaire. Questions focused on perceptions of research, the contribution of participants' own experience in implementing knowledge to practice, sources, and barriers for accessing and implementing EBP, preferred methods of feedback, and the required qualities of practitioners. RESULTS: All practitioners reported using EBP, while most coaches and athletes believed that EBP contributes to individual performance and preparation (>85%). Practitioners' preferred EBP information sources were "peer-reviewed journals" and "other practitioners within their sport," while athlete sources were "practitioners within their sport" and "other athletes within their sport." As primary barriers to accessing and implementing research, practitioners highlighted "time constraints," "poor research translation," and "nonapplicable research." Practitioners ranked "informal conversation" as their most valued method of providing feedback; however, coaches prefer feedback from "scheduled meetings," "online reports," or "shared database." Both athletes and coaches value "excellent knowledge of the sport," "experience," and "communication skills" in practitioners disseminating EBP. CONCLUSION: Practitioners, coaches, and athletes believe in the importance of EBP to their profession, although practitioners reported several barriers to accessing and implementing research as part of EBP. Athletes place a high value on experienced practitioners who have excellent knowledge of the sport and communication skills. Collectively, these findings can be used to further stakeholder understanding regarding EBP and the role of research to positively influence athlete health.

Does Cold-Water Immersion After Strength Training Attenuate Training Adaptation?

PURPOSE: Cold-water immersion is increasingly used by athletes to support performance recovery. Recently, however, indications have emerged suggesting that the regular use of cold-water immersion might be detrimental to strength training adaptation. METHODS: In a randomized crossover design, 11 participants performed two 8-week training periods including 3 leg training sessions per week, separated by an 8-week "wash out" period. After each session, participants performed 10 minutes of either whole-body cold-water immersion (cooling) or passive sitting (control). Leg press 1-repetition maximum and countermovement jump performance were determined before (pre), after (post) and 3 weeks after (follow-up) both training periods. Before and after training periods, leg circumference and muscle thickness (vastus medialis) were measured. RESULTS: No significant effects were found for strength or jump performance. Comparing training adaptations (pre vs post), small and negligible negative effects of cooling were found for 1-repetition maximum (g = 0.42; 95% confidence interval [CI], -0.42 to 1.26) and countermovement jump (g = 0.02; 95% CI, -0.82 to 0.86). Comparing pre versus follow-up, moderate negative effects of cooling were found for 1-repetition maximum (g = 0.71; 95% CI, -0.30 to 1.72) and countermovement jump (g = 0.64; 95% CI, -0.36 to 1.64). A significant condition × time effect (P = .01, F = 10.00) and a large negative effect of cooling (g = 1.20; 95% CI, -0.65 to 1.20) were observed for muscle thickness. CONCLUSIONS: The present investigation suggests small negative effects of regular cooling on strength training adaptations.

Effects of Postexercise Sauna Bathing on Recovery of Swim Performance.

PURPOSE: Despite indications of positive effects of sauna (SAU) interventions, effects on performance recovery are unknown. The aim of the current study was to investigate acute effects of SAU bathing after an intensive training session on recovery of swim performance. METHODS: In total, 20 competitive swimmers and triathletes (3 female and 17 male) with a minimum of 2 y of competition experience (national level or higher) participated in the study. Athletes completed an intensive training session followed by either a SAU bathing intervention or a placebo (PLAC) condition in a randomized order. SAU consisted of 3 × 8 min of SAU bathing at 80-85°C, whereas during PLAC, athletes applied a deidentified, pH-balanced massage oil while passively resting in a seated position. Prior to training, swimmers conducted a 4 × 50-m all-out swim test that was repeated on the following morning. Furthermore, subjective ratings of fatigue and recovery were measured. RESULTS: Swimmers performed significantly worse after SAU (4 × 50-m pre-post difference: +1.69 s) than after PLAC (-0.66 s; P = .02), with the most pronounced decrease in the first 50 m (P = .04; +2.7%). Overall performance of 15 athletes deteriorated (+2.6 s). The subjective feeling of stress was significantly higher after SAU than after PLAC (P = .03). CONCLUSION: Based on published findings, the smallest substantial change in swimming performance is an increase in time of more than 1.2 s; thus, the observed reductions appear relevant for competitive swimmers. According to the current results, coaches and athletes should be careful with postexercise SAU if high-intensity training and/or competitions are scheduled on the following day.