Relation Between Training Load and Recovery-Stress State in High-Performance Swimming

The influence of competitive anxiety of Chinese elite swimmers

Background

Competitive anxiety is a common stress response in competitive environments, influencing sports performance, particularly among elite swimmers.

Purpose

This study aims to examine how the characteristics of competitive anxiety impact sports performance across different phases of competitive preparation, alongside its correlation with trait anxiety.

Methods

A longitudinal research design, integrating quantitative and qualitative approaches, was employed with 20 swimmers from the Chinese national swimming team participating in both the 2023 Fukuoka World Championships and the Hangzhou Asian Games. The mental readiness form-3 (MRF-3) scale was employed at four time points during the preparation period for longitudinal tracking, complemented by the trait anxiety inventory (T-AI) scale to assess trait anxiety.

Results

The study identified a negative correlation between cognitive anxiety and somatic anxiety among elite swimmers, with confidence demonstrating a positive correlation. Additionally, there was a significant between trait anxiety and competitive anxiety (p < 0.05). Variations in competitive anxiety were found at different stages of the preparation cycle (F = 15.074; 11.627; 19.552, p < 0.05), impacting sport performance.

Conclusion

To optimise performance, tailored psychological intervention programs should be developed and implemented to address the distinct characteristics of competitive anxiety experienced by elite swimmers throughout the preparation phases.

Identifying evidence-practice gaps for shoulder injury risk factors in competitive swimmers: uniting literature and expert opinion

OBJECTIVES

To identify evidence-practice gaps regarding shoulder injury risk factors in competitive swimmers.

METHODS

We gathered insights from 27 swimming experts including elite swimmers, coaches, high-performance staff and applied researchers using Concept Mapping. Participants brainstormed, sorted and rated (from 1 (least) to 10 (most) important and modifiable) their ideas of shoulder injury risk factors in competitive swimmers. Proposed risk factors rated above the grand mean for importance (6.2±0.4) or modifiability (6.5±0.5) ratings were considered highly important/modifiable. Expert opinions were then juxtaposed with systematic review findings to identify overlaps or convergences.

RESULTS

Brainstorming generated 126 proposed shoulder injury risk factors for competitive swimmers, subsequently refined to 61 unique proposed risk factors by removing duplicates and combining similar responses. The participants sorted the 61 risk factors into seven distinct clusters. Experts perceived 36/61 proposed risk factors as highly important, of which 6 were supported by literature, 6 showed no association with injury, 2 had conflicting evidence and the remaining 22 have not yet been investigated, suggesting an evidence-practice gap. Three proposed risk factors 'inconsistent training load', 'poor stroke technique' and 'low posterior shoulder strength-endurance' exhibited high perceived importance, high perceived modifiability and supporting evidence.

CONCLUSION

An evidence-practice gap was identified for 28 proposed risk factors perceived as highly important by swimming experts despite either (1) no relevant empirical research (n=22), or (2) no association with injury (n=6) from synthesised evidence. Greater collaboration between researchers and practitioners is needed to effectively address shoulder injury risk factors in competitive swimmers.

Effect of Foam Roll recovery method on performance in water polo players: a randomized controlled trial

OBJECTIVES

This intervention study aimed to evaluate how the use of Foam Roller (FR) as a recovery strategy affects water polo performance after a seven-week (28-session) program.

DESIGN

A randomized controlled trial.

METHODS

Thirty water polo players (14 male amateur players and 16 female sub-elite players) were assigned by means of sealed opaque envelopes to the control group (CG) or Foam Roller Group (FRG) and performed the same total number and intensity of training sessions. Test protocols were performed before (pretest), in-test (week 5), and after the intervention period (posttest). These included water polo-specific performance tests such as in-water boost, throwing speed, and 20 m sprint swimming tests. In addition, during the intervention, heart rate (HR), the scale of perceived exertion of the session (sRPE), and total quality recovery scale (TQR) data were recorded.

RESULTS

There were no differences in the baseline values in any of the variables analyzed between CG and FRG. A small decrease in in-water boost was observed in CG (-2%, ES = -0.35 [-0.95: 0.26], p = 0.016, very likely small) and in FRG (-2%, ES = -0.33 [-0.93: 0.27], p = 0.021, likely small). No significant changes were found in either the 20 m swim test or the throwing test in CG and FRG. No clear differences among groups and weeks were found in sRPE, TQR and HR.

CONCLUSION

The findings indicate that the use of FR as a recovery tool after training and matches is not useful in water polo players.

A novel approach for sports injury risk prediction: based on time-series image encoding and deep learning

The rapid development of big data technology and artificial intelligence has provided a new perspective on sports injury prevention. Although data-driven algorithms have achieved some valuable results in the field of sports injury risk assessment, the lack of sufficient generalization of models and the inability to automate feature extraction have made it challenging to deploy research results in the real world. Therefore, this study attempts to build an injury risk prediction model using a combination of time-series image encoding and deep learning algorithms to address this issue better. This study used the time-series image encoding approach for feature construction to represent relationships between values at different moments, including Gramian Angular Summation Field (GASF), Gramian Angular Difference Field (GADF), Markov Transition Field (MTF), and Recurrence Plot (RP). Deep Convolutional Auto-Encoder (DCAE) learned the image-encoded data for representation to obtain features with good discrimination, and the classifier was performed using Deep Neural Network (DNN). The results from five repeated experiments show that the GASF-DCAE-DNN model is overall better in the training (AUC: 0.985 ± 0.001, Gmean: 0.930 ± 0.007, Sensitivity: 0.997 ± 0.003, Specificity: 0.868 ± 0.013) and test sets (AUC: 0.891 ± 0.026, Gmean: 0.830 ± 0.027, Sensitivity: 0.816 ± 0.039, Specificity: 0.845 ± 0.022), with good discriminative power, robustness, and generalization ability. Compared with the best model reported in the literature, the AUC, Gmean, Sensitivity, and Specificity of the GASF-DCAE-DNN model were higher by 23.9%, 27.5%, 39.7%, and 16.2%, respectively, which confirmed the validity and practicability of the model in injury risk prediction. In addition, differences in injury risk patterns between the training and test sets were identified through shapley additivity interpretation. It was also found that the training volume was an essential factor that affected injury risk prediction. The model proposed in this study provides a powerful injury risk prediction tool for future sports injury prevention practice.

Effect of training load on sleep parameters and biochemical fatigue markers in elite swimmers

The effect of strenuous exercise on sleep patterns in swimmers is equivocal. Therefore, the purpose of the study was to describe possible changes in sleep parameters among elite swimmers subjected to different training loads (TL). Methods: Eighteen elite swimmers (8 females) were monitored across two high-volume preparatory 1-wk periods (P1, P2) and a lower-volume tapering 1-wk period (P3) before a major competition. Internal (the session rating of perceived exertion [sRPE]) and external TL (training duration and volume) were measured, along with several sleep indices (e.g., bedtime, get-up time, sleep time, wake after sleep onset [WASO]). Serum measurements of urea, creatine kinase (CK), testosterone and cortisol were taken before and after training sessions at the beginning (Mondays) and end (Fridays) of each micro cycle. Athlete TL decreased significantly in a stepwise manner from P1 to P2 and from P2 to P3. Of all sleep parameters, only significant differences in bedtime and get-up time emerged (P3 > P1 and/or P2). Sleep duration (~6.3 h) or quality (WASO: 41-45 min) were also unaffected by TL. CK levels declined from P1 to P3 (d = -0.8), and from P2 to P3 (d = -0.6). Positive exercise-induced changes in CK were also seen in each training period. The other biomarkers did not show the same temporal or acute patterns. Irrespective of the TL, the monitored swimmers experienced insufficient and fragmented sleep across this study. Neither sleep quality nor quantity were affected by different magnitudes of TL. Among the biochemical markers of fatigue, baseline plasma CK activity best reflected the physiological response to TL.

Asynchronous Heart Rate Variability Biofeedback Protocol Effects on Adolescent Athletes' Cognitive Appraisals and Recovery-Stress States

This study examined the effect of an asynchronous heart rate variability biofeedback (HRV-BFBasync) protocol on national-level adolescent swimmers' cognitive appraisals and recovery-stress states during a six-week ecological training period. A polynomial mixed-effects multilevel regression analysis approach was used with 27 adolescent national-level swimmers randomly assigned to an intervention group (n = 14) and a control group (n = 13). Six waves of assessments of cognitive appraisals and recovery-stress states were completed during six weeks of training preparation in ecological conditions. The results revealed that the HRV-BFBasync protocol significantly predicts lower levels of biopsychosocial stress states and cognitive stress. However, no significant effects were found for biopsychosocial recovery scales and cognitive perceived control. The results suggested that total stress states, sport-specific stress, and cognitive perceived stress evolutions are a function of polynomial time third-degree interactions with HRV-BFB protocol. Overall, this study suggested that the HRV-BFBasync protocol leads adolescent athletes to experience lower biopsychosocial and cognitive stress levels during training periodization. Our results also suggest that HRV-BFB induces complex evolutions over time for stress and recovery states but does not have a predictive function for the recovery states and perceived control.

Case study of IMU loads and self-reported fatigue monitoring of water polo goalkeepers preparing for the Olympic games

Introduction

Measurement of training in water polo goalkeepers has focused first on psycho-physiological variables, but also on external volume estimated with wearable sensors. However, there are limited studies exploring training monitoring in water polo goalkeepers longitudinally.

Methods

Three female senior national team goalkeepers participated in this study from May to August 2021. Internal loads were defined using session rating of perceived exertion (sRPE). Tri-axial accelerations and angular velocities were measured with an inertial measurement unit (IMU) placed on the lower back to measure external loads. Relationships between self-reported and IMU-derived metrics were explored using Spearman correlations. Two-way ANOVAs were used to assess differences between session types and between athletes.

Results

In total, 247 sessions were collected (159 practices, 67 matches and 21 game warm up), with 155 sessions having complete data. IMU metrics, such as number of kicks, number of jumps or player-load showed high correlation with each other (ρ = 0.80-0.88). There was also a moderate correlation (ρ = 0.47, 95% CI = 0.33-0.58) between sRPE and player-load measured with the IMU. ANOVA tests showed that there were significant differences between athletes for sRPE (p < 0.01) but not for player load (p = 0.47). There were no interactions between athletes and training types, except for index score (p < 0.01).

Conclusions

This study shows that monitoring of training loads can be performed successfully in water polo goalkeepers using a combination of self-reported and IMU measures. Self-reported outcomes can be expected to vary significantly across athletes within the same session, while IMU metrics vary across training situations. Finally, coaches should be mindful of missing data, as they can skew the interpretation of training loads.

The Effects Of Differing Density Of Swim-Training Sessions On Shoulder Range Of Motion and Isometric Force Production In National and University Level Swimmers

Background

Well-developed physical qualities (i.e., greater load capacity) in athletes can provide protection against injuries. Although higher competitive level swimmers have more developed physical qualities, no studies have investigated how physical qualities of the shoulder respond to a swim-training session in different competitive levels.

Purpose

To compare baseline shoulder external rotation range of motion (ER ROM) and isometric peak torque of the shoulder internal rotators (IR) and external rotators (ER) between national and university level swimmers with differing training volumes. To compare the post-swim changes of these physical qualities between groups.

Study design

Cross-sectional.

Methods

Ten male swimmers (age= 18.7 ± 1.2 years) were divided into high-load (N= 5 national-level, weekly swim-volume= 37.0 ± 2.7 km) and low-load groups (N= 5 university-level, weekly swim-volume= 6.8 ± 1.8 km). For each group, shoulder active ER ROM and isometric peak torque of the shoulder IR and ER were measured before and immediately after a high-intensity swim-training session (for each group, the hardest swim-session of the week was analyzed). The results were evaluated by the level of significance (p-value), effect size, and whether changes exceeded the measurement error.

Results

University-level swimmers had lower baseline ER torque (p= 0.006; d= 2.55) and IR torque (p= 0.011; d= 2.42) than national-level swimmers. For post-swim analysis, ER ROM decreased more in university swimmers (change= -6.3° to -8.4°; d= 0.75-1.05) than national counterparts (change= -1.9° to -5.7°; d= 0.43-0.95). Greater drops in rotation torque were found in university swimmers (IR change= -15% to -21.0%; d= 0.83-1.66; ER change= -9.0% to -17.0%; d= 1.14-1.28) compared to national swimmers (IR change= -10.0% to -13.0%; d= 0.61-0.91; ER change= -3.7% to -9.1%; d= 0.50-0.96). The average change of all tests in university swimmers exceeded the minimal detectable change (MDC), whereas in national level swimmers some tests exceeded the MDC. Despite this, only post-swim ER torque in the dominant side (p= 0.003; d= 1.18) was significantly lower in university swimmers (possibly due to the small sample size).

Conclusions

University swimmers have less baseline shoulder external and internal rotator torque and had greater drops of all shoulder physical qualities after a swim-training session, which may have implications for injury risk. However, due to the sample size, the results have to be interpreted with caution.

Level of evidence

3.

Effect of High-Volume Training on Psychological State and Performance in Competitive Swimmers

This study aimed to examine the effect of four weeks of aquatic high-volume training (HVT) on the psychological state (somatic, cognitive anxiety, and self-confidence) and sprint swimming performance (50 m front crawl) compared to the standard training program (moderate volume training) in competitive swimmers. Twenty-eight male competitive swimmers participated in this study and were randomly allocated into two groups: HVT group (n = 14; age = 16.4 ± 0.31 years) and control group that underwent the standard training program (n = 14; age = 16.1 ± 0.30 years). All psychological state variables and swimming performance were measured in pre and post-test. Our findings showed a significant increase in anxiety state (34.13% to 45.83%; ES = 3.26 to 3.38) and a significant decrease in self-confidence (18.43%; ES = 2.39) after four weeks of HVT, while all psychological state variables remained unchanged in the control group (p > 0.05). In addition, our results showed no significant enhancement in swimming performance in both groups (p > 0.05). The sudden increase in training mileage negatively affected the anxiety, decreasing the state of self-confidence of the participants. In addition, four weeks of high training volume are insufficient to improve swimming performance. To conclude, gradually increasing the volume of the training load may be an adequate solution to promote adaptation to the effort, thus maintaining the stability of the psychological state of swimmers. In addition, it is recommended to integrate a concurrent mental preparation program with high-volume training to monitor the psychological state of competitive swimmers.

Sleep and Athletic Performance: Impacts on Physical Performance, Mental Performance, Injury Risk and Recovery, and Mental Health: An Update

Sleep health is an important consideration for athletic performance. Athletes are at high risk of insufficient sleep duration, poor sleep quality, daytime sleepiness and fatigue, suboptimal sleep schedules, irregular sleep schedules, and sleep and circadian disorders. These issues likely have an impact on athletic performance via several domains. Sleep loss and/or poor sleep quality can impair muscular strength, speed, and other aspects of physical performance. Sleep issues can also increase risk of concussions and other injuries and impair recovery after injury. Cognitive performance is also impacted in several domains, including vigilance, learning and memory, decision making, and creativity.

International survey of training load monitoring practices in competitive swimming: How, what and why not?

OBJECTIVE

The purpose of this study is to identify the training load (TL) monitoring practices employed in real-world competitive swimming environments. The study explores data collection, analysis and barriers to TL monitoring.

DESIGN

Cross-sectional.

SETTING

Online survey platform.

PARTICIPANTS

Thirty-one responders working in competitive swimming programmes.

MAIN OUTCOME MEASURES

Methods of data collection, analysis, level of effectiveness and barriers associated with TL monitoring.

RESULTS

84% of responders acknowledged using TL monitoring, with 81% of responders using a combination of both internal and external TL, in line with current consensus statements. Swim volume (mileage) (96%) and session rate of perceived exertion (sRPE) (92%) were the most frequently used, with athlete lifestyle/wellness monitoring also featuring prominently. Thematic analysis highlighted that "stakeholder engagement", "resource constraints" or "functionality and usability of the systems" were shared barriers to TL monitoring amongst responders.

CONCLUSIONS

Findings show there is a research-practice gap. Future approaches to TL monitoring in competitive swimming should focus on selecting methods that allow the same TL monitoring system to be used across the whole programme, (pool-based training, dryland training and competition). Barriers associated with athlete adherence and coach/National Governing Body engagement should be addressed before a TL system implementation.

What Is the Optimal Strength Training Load to Improve Swimming Performance? A Randomized Trial of Male Competitive Swimmers

This study aimed to compare the effectiveness of high, moderate, and low resistance training volume-load of maximum strength training on muscle strength and swimming performance in competitive swimmers. Thirty-three male swimmers were randomly allocated to high (age = 16.5 ± 0.30 years), moderate (age = 16.1 ± 0.32 years) and a low resistance training volume-load group (age = 15.9 ± 0.31). This study was carried out in mid-season (January to March). Pre and post strength (e.g., repetition maximum [1RM] leg extension and bench press tests), swimming (25, 50 m front-crawl), start (speed, time, distance) and turn (time of turn) performance tests were conducted. Our findings revealed a large main effect of time for 1RM bench press: d = 1.38; 1RM leg extension: d = 1.55, and for 25 (d = 1.12), and 50 m (d = 1.97) front-crawl, similarly for start and turn performance (d = 1.28-1.46). However, no significant Group × Time interactions were shown in all strength swimming performances, start and turn tests (p > 0.05). In conclusion, low training loads have been shown to elicit the same results as moderate, and high training loads protocol. Therefore, this study shows evidence that the addition of low training volume-loads as a regular part of a maximal strength training regime will elicit improvements in strength and swimming performance.

Increases in RPE Rating Predict Fatigue Accumulation Without Changes in Heart Rate Zone Distribution After 4-Week Low-Intensity High-Volume Training Period in High-Level Rowers

Purpose: The aim of this study was to investigate the interaction of training load quantification using heart rate (HR) and rating of perceived exertion (RPE)-based methodology, and the relationship between internal training load parameters and subjective training status (Fatigue) in high-level rowers during volume increased low-intensity training period.

Methods: Training data from 19 high-level rowers (age 23.5 ± 5.9 years; maximal oxygen uptake 58.9 ± 5.8 ml·min⁻¹·kg⁻¹) were collected during a 4-week volume increased training period. All individual training sessions were analyzed to quantify training intensity distribution based on the HR time-in-zone method (i.e., HR Z1, HR Z2, and HR Z3) determined by the first and second ventilatory thresholds (VT1/VT2). Internal training load was calculated using session RPE (sRPE) to categorize training load by effort (i.e., sRPE1, sRPE2, and sRPE3). The Recovery-Stress Questionnaire for Athletes (RESTQ-Sport) questionnaire was implemented after every week of the study period.

Results: No differences were found between the respective HR and effort-based zone distributions during the baseline week (p > 0.05). Compared to HR Z1, sRPE1 was significantly lower in weeks 2–4 (p < 0.05), while sRPE2 was higher in weeks 2–3 compared to HR Z2 (p < 0.05) and, in week 4, the tendency (p = 0.06) of the higher amount of sRPE3 compared to HR Z3 was found. There were significant increases in RESTQ-Sport stress scales and decreases in recovery scales mostly during weeks 3 and 4. Increases in the Fatigue scale were associated with the amounts of sRPE2 and sRPE3 (p = 0.011 and p = 0.008, respectively), while no associations with Fatigue were found for HR-based session quantification with internal or external training load variables.

Conclusion: During a low-intensity 4-week training period with increasing volume, RPE-based training quantification indicated a shift toward the harder rating of sessions with unchanged HR zone distributions. Moderate and Hard rated sessions were related to increases in Fatigue. Session rating of perceived exertion and effort-based training load could be practical measures in combination with HR to monitor adaptation during increased volume, low-intensity training period in endurance athletes.

Training Distribution During a Paralympic Cycle for a Multiple Swimming Champion With Paraplegia: A Case Report

PURPOSE

To describe the training volume, intensity distribution, and use of swimming styles during a Paralympic cycle in a multiple swimming champion with paraplegia.

METHODS

The female Paralympic swimmer was 23-26 years of age and had a body mass of 60 to 62 kg and a body height of 174 cm. She has a spinal cord injury at the Th6 level, competed in the S5/SB4 Para swimming classes, and uses a wheelchair for mobility. Training time, as well as distance in the different intensity zones and swimming styles, was registered with the "workouts for swim coaches" software throughout a full Paralympic cycle.

RESULTS

The Para swimmer performed a total of 388, 524, 471, and 656 annual hours of swimming, corresponding to 1126, 1504, 1463, and 1993 km, in the 2012-13, 2013-14, 2014-15, and 2015-16 seasons, respectively. In addition, she performed 1 to 3 weekly dry-land strength sessions and 4 to 6 weekly dry-land basic skill sessions. She conducted 91% to 94% of the swimming distance in each macrocycle at low intensity, 2% to 4% at moderate intensity, and 3% to 6% at high intensity. She performed 78% to 84% of the swimming distance in each macrocycle in the freestyle swimming technique and the remaining 16% to 22% in the backstroke, breaststroke, and butterfly techniques.

CONCLUSION

This case study exemplifies how a female Paralympic swimmer with paraplegia progressed her training in the seasons leading up to the Paralympic Games, reaching an annual training distance of 2000 km, which is similar to that of able-bodied swimmers.

The Development and Evaluation of a Training Monitoring System for Amateur Rugby Union

A training monitoring system (TMS) should be both attainable and scientifically grounded; however, the optimal method of monitoring training is not yet fully understood. The purpose of this study was to develop and evaluate an online TMS for amateur rugby union. The experimental approach to the problem consisted of five phases: (1) establishing the current training and training load (TL) monitoring practices of amateur rugby union teams, (2) designing and developing the TMS, (3) recruiting teams and subsequently introducing the TMS, (4) supporting the strength and conditioning (S&C) coaches using the TMS, and (5) evaluating the TMS. The findings of this study support the use of an online TMS as a useful and effective method of facilitating training prescription and design in an effort to reduce injury risk and enhance performance. The main barriers impeding player compliance are the lack of feedback on their data and evidence of its use in training design, coaching, and prescription. The effectiveness of the system is dependent on the extent to which the associated challenges are mitigated to ensure quality and consistent data. However, this study offers a method of monitoring training that can be effective while also establishing pitfalls to avoid for both practitioners and researchers alike.

Workload a-WEAR-ness: Monitoring Workload in Team Sports With Wearable Technology. A Scoping Review

OBJECTIVES

To (1) identify the wearable devices and associated metrics used to monitor workload and assess injury risk, (2) describe the situations in which workload was monitored using wearable technology (including sports, purpose of the analysis, location and duration of monitoring, and athlete characteristics), and (3) evaluate the quality of evidence that workload monitoring can inform injury prevention.

DESIGN

Scoping review.

LITERATURE SEARCH

We searched the CINAHL, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Embase, HealthSTAR, MEDLINE, PsycINFO, SPORTDiscus, and Web of Science databases.

STUDY SELECTION CRITERIA

We included all studies that used wearable devices (eg, heart rate monitor, inertial measurement units, global positioning system) to monitor athlete workload in a team sport setting.

DATA SYNTHESIS

We provided visualizations that represented the workload metrics reported, sensors used, sports investigated, athlete characteristics, and the duration of monitoring.

RESULTS

The 407 included studies focused on team ball sports (67% soccer, rugby, or Australian football), male athletes (81% of studies), elite or professional level of competition (74% of studies), and young adults (69% of studies included athletes aged between 20 and 28 years). Thirty-six studies of 7 sports investigated the association between workload measured with wearable devices and injury.

CONCLUSION

Distance-based metrics derived from global positioning system units were common for monitoring workload and are frequently used to assess injury risk. Workload monitoring studies have focused on specific populations (eg, elite male soccer players in Europe and elite male rugby and Australian football players in Oceania). Different injury definitions and reported workload metrics and poor study quality impeded conclusions regarding the relationship between workload and injury. J Orthop Sports Phys Ther 2020;50(10):549-563. doi:10.2519/jospt.2020.9753.

Does an Optimal Relationship Between Injury Risk and Workload Represented by the "Sweet Spot" Really Exist? An Example From Elite French Soccer Players and Pentathletes

Objective

To examine the relationships between the occurrence and severity of injuries using three workload ratios (ACWR, EWMA, REDI) in elite female soccer players and international male and female pentathletes.

Materials and Methods

Female soccer players in the U16 to U18 national French teams (n = 24) and international athletes (n = 12, 4 women and 8 men) in the French modern pentathlon team were monitored throughout an entire season. The Acute Chronic Workload Ratio (ACWR), the Exponentially Weighted Moving Averages (EWMA), and the Robust Exponential Decreasing Index (REDI) were calculated for internal load by the ROE method in soccer and external load in pentathlon. The occurrence and severity of injuries (determined according to time-loss) were quantified in the sweet spot zone [0.8; 1.3] and compared to the other zones of load variation: [0; 0.8], [1.3; 1.5], [1.5; +8], using the three ratios.

Results

Over the study period, a total of sixty-six injuries (2.75 per athlete) were reported in the soccer players and twelve in pentathletes (1 per athlete). The cumulative severity of all injuries was 788 days lost in soccer and 36 in pentathlon: respectively, 11.9 days lost per injury in soccer player and 3.0 per pentathlete. The mean values across the three methods in soccer showed a higher number of injuries detected in the [0; 0.8] workload ratio zone: 22.3 ± 6.4. They were 17.3 ± 3.5 in the sweet spot ([0.8-1.3] zone) and 17.6 ± 5.5 in the [1.5; +8] zone. In comparison to the [1.5; +8] zone, soccer players reported a higher number of days lost to injuries in the presumed sweet spot and in the [0-0.8] zone: 204.7 ± 28.7 and 275.0 ± 120.7 days, respectively. In pentathletes, ten of the twelve injuries (83.3%) occurred in the presumed sweet spot. REDI was the only method capable of tracking workloads over all-time series.

Conclusion

In the present cohort of elite soccer players and pentathletes, acute chronic workload calculations showed an association with injury occurrence and severity but did not provide evidence supporting existence of a sweet spot diminishing injury risk.

Proteomic Profiling and Monitoring of Training Distress and Illness in University Swimmers During a 25-Week Competitive Season

Purpose

To evaluate relationships of proteomics data, athlete-reported illness, athlete training distress (TDS), and coaches’ ratings of distress and performance over the course of the competitive season.

Methods

Thirty-five NCAA Division II swimmers were recruited to the study (male n = 19, female n = 16; age 19.1 ± 1.6 years). Athletes provided fingerprick dried blood spot (DBS) samples, illness symptoms, and TDS every Monday for 19 of 25 weeks in their season. Coaches monitored performance and rated visual signs of distress. DBS samples were analyzed for a targeted panel of 12 immune-related proteins using liquid chromatography/mass spectrometry (LC/MS).

Results

Thirty-two swimmers completed the protocol. The data were grouped in 2–3 weeks segments to facilitate interpretation and analysis of the data. TDS scores varied between athletes, and were highest during the early fall conditioning ramp up period (8.9 ± 1.6 at baseline to a peak of 22.6 ± 2.0). The percent of athletes reporting illness was high throughout the season (50–78%). Analysis of TDS using Principle Component Analysis (PCA) revealed that 40.5% of the variance (PC1) could be attributed to illness prevalence, and TDS scores for the athletes reporting illness and no illness were different across the season (P < 0.001). The coaches’ ratings of swim performance and swimmer’s distress, sex, and racing distance (sprinters, middle distance, long distance) were not correlated with PC1. Linear Discriminant Analysis (LDA) analysis of the data showed a separation of the baseline weeks from exam weeks with or without competitions, and with competitions alone (p < 0.001). Seven of the 12 proteins monitored over the course of training were upregulated, and the addition of the protein data to LDA analysis enhanced the separation between these groups of weeks.

Conclusion

TDS and illness were related in this group of 32 collegiate swimmers throughout the competitive season, and expression of immune proteins improved the statistical separation of baseline weeks from the most stressful weeks. TDS data provided by the swimmers did not match their coaches’ ratings of distress and swim performance. The importance of the immune system in the reaction to internal and external stress in athletes should be an area of further research.

Sleep and Athletic Performance: Impacts on Physical Performance, Mental Performance, Injury Risk and Recovery, and Mental Health

Research has characterized the sleep of elite athletes and attempted to identify factors associated with athletic performance, cognition, health, and mental well-being. Sleep is a fundamental component of performance optimization among elite athletes, yet only recently embraced by sport organizations as an important part of training and recovery. Sleep plays a crucial role in physical and cognitive performance and is an important factor in reducing risk of injury. This article aims to highlight the prevalence of poor sleep, describe its impacts, and address the issue of sport culture surrounding healthy sleep.

Modification and Applicability of Questionnaires to Assess the Recovery-Stress State Among Adolescent and Child Athletes

Despite the general consensus regarding the implementation of self-report measures in the training monitoring, there is a lack of research about their applicability and comprehensibility among developing athletes. However, this target group needs special considerations to manage the increasing training demands while maintaining health and performance. This study deals with challenges of applying recovery-stress questionnaires which were validated with adult populations among developing athletes and presents a possible approach to enhance their applicability. In two phases, the Acute Recovery and Stress Scale (ARSS), a 32-adjective list covering eight scales, and the 8-item derived version, the Short Recovery and Stress Scale (SRSS) were answered by 1052 athletes between 10 and 16 years. Phase 1 included 302 14- to 16-year-old athletes who used the original questionnaires with the additional option to mark "I don't understand," while modified versions with additional explanations (phase 2) were applied to 438 adolescents (14.7 ± 0.6 years) and 312 child athletes (11.8 ± 1.1 years). Data of the original validation sample (n = 442) were reanalyzed to examine measurement invariance between adults and adolescents. The results showed comparable psychometric properties to the validation sample (e.g., r it > 0.30) and acceptable fit indices via confirmatory factor analyses (CFA), although more difficulties and limitations were present within the younger groups (e.g., Cronbach's α between 0.50 and 0.87), especially among 10- and 11-year-olds. The original as well as the modified SRSS, on the other hand, indicated good applicability (Cronbach's α between 0.72 and 0.80). Multigroup CFA revealed measurement invariance of the original ARSS among adults and adolescents and of the modified ARSS among adolescents and children. Overall, the present study confirmed the assumption that questionnaires designed by and for adults cannot be directly transferred to younger athletes. The peculiarities and differences in the cognitive and affective development of each age group need to be considered. Future research needs to identify a cut-off age to start the proper use of psychometric tools, especially for state-oriented assessments for routine application in training monitoring. Further modifications and long-term investigations are necessary to implement psychometric monitoring in high-performance environments within youth sport.