Perceived load, fatigue and recovery responses during congested and non-congested micro-cycles in international football tournaments

Influence of Travel Demands and Match Load on Recovery Following Postmatch Travel in National-Team Footballers

PURPOSE

This study investigated the relationship between travel demands and match loads on perceptual recovery, fatigue, and sleep following postmatch travel in national football teams. In addition, the influence of travel demands and the time between match kickoff and travel departure on postmatch recovery was examined.

METHODS

Match-running load (via GPS) and travel data were obtained from 79 male national-team footballers. Postmatch travel duration, direction, context, time-zone difference, and time between kickoff and travel departure were collated. Athletes provided perceptual ratings of fatigue, soreness, sleep, stress, and recovery from 1 day prematch through to 3 days after postmatch travel. Linear mixed models assessed the influence of match load and travel on perceptual ratings for 3 days posttravel. Additional models assessed a standardized postmatch time point of match day + 3 to determine whether timing and extent of travel influenced recovery.

RESULTS

Higher match loads were associated with poorer recovery, fatigue, soreness, and sleep (P = .001-.032). Athletes reported poorer fatigue, soreness, and recovery when traveling from national teams back to clubs compared with between national-team matches (P < .001). Traveling eastward was associated with poorer sleep (P = .004). Longer periods between kickoff and travel departure were associated with poorer sleep on match day + 3 (P = .003).

CONCLUSIONS

Perceptual recovery, fatigue, sleep, and soreness following postmatch travel were affected by both match load and travel demands. Greater match loads and eastward postmatch travel may impair recovery. In addition, departing later after a match was associated with poorer sleep on match day + 3; however, no relationships existed to any other recovery measures.

The short-term relation between load and acute psychophysiological responses in football: a meta-analysis and methodological considerations

Relations between load and acute psychophysiological responses have been widely studied in football. However, due to the large heterogeneity in contexts, operationalization, and results, the direction and strength of these relations remain unclear. In this meta-analysis, we examine the relation between load and typical acute (i.e. within one week) responses - wellbeing, recovery, and heart rate measures - in football players from all football codes (soccer, rugby, futsal, American football, and Australian rules football). We consulted PubMed, Web of Science, and CINAHL up to the 19th of June 2024, and included 62 articles and 1,474 participants in the meta-analysis. Subsequently, we estimated 12 meta-analysis models and applied meta-regression models to explore the influence of several moderators. Significant relations were found between load and overall wellbeing (r = -0.33 [95%CI: -0.48; -0.19]), muscle soreness (r = -0.36 [95%CI: -0.49; -0.24]), fatigue (r = -0.41 [95%CI: -0.56; -0.26]), sleep quality (r = -0.21 [95%CI: -0.31; -0.10]), and stress (r = -0.16 [95%CI: -0.26; -0.06]). Given the high risk of bias, inconsistency (wide prediction intervals), and imprecision, the certainty in these findings based on the GRADE assessment is very low. Additionally, the high risk of bias scores indicates that the overall quality of the included studies is low. In conclusion, this meta-analysis provides comprehensive information on the acute responses of the athlete to load, and directions for improvement of the quality of future studies.

Factors Informing Training Load During the Transition From Club to National Football Teams

PURPOSE

This study examined the relationship of precamp match exposure, travel demands, perceptual wellness, and musculoskeletal screening with ensuing training load (TL) during national-team (NT) duties for international footballers (soccer).

METHODS

Match minutes and days since last match prior to NT arrival were collected for match exposure. Travel duration and time-zone difference were included as travel demands. Perceptual fatigue, soreness, sleep quality, and stress scores were collected via self-report questionnaire on arrival to NT. Musculoskeletal testing on day 1 of NT included knee to wall and hip internal and external rotation. Relative TL across the first 3 days of NT camp was measured via total distance, high-speed running distance, very high-speed running distance, and accelerations and decelerations per minute. Linear mixed models determined the influence of independent variables on respective TL metrics, with the player included as a random effect.

RESULTS

Total distance, high-speed running, very high-speed running, and decelerations per minute were all highest on day 3 (P < .001). Small relationships existed (R2 < .15) between decreased total distance per minute and increased soreness (P = .037), while decreased high-speed running per minute was associated with increased fatigue (P = .017). Small associations existed between decreased accelerations per minute, increased hip internal rotation (P < .001), fatigue (P = .033), and knee to wall (P = .016), while decreased decelerations per minute were associated with increased soreness (P = .001), knee to wall (P = .024), and days between recent match and arrival (P = .003).

CONCLUSIONS

Very small relationships existed between fatigue, soreness, musculoskeletal screening, and prior match exposure with TL. The larger influence of camp day suggests that deliberate periodization of training is a major factor for prescription on arrival into NT duties.

What We Do Not Know About Stretching in Healthy Athletes: A Scoping Review with Evidence Gap Map from 300 Trials

BACKGROUND

Stretching has garnered significant attention in sports sciences, resulting in numerous studies. However, there is no comprehensive overview on investigation of stretching in healthy athletes.

OBJECTIVES

To perform a systematic scoping review with an evidence gap map of stretching studies in healthy athletes, identify current gaps in the literature, and provide stakeholders with priorities for future research.

METHODS

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 and PRISMA-ScR guidelines were followed. We included studies comprising healthy athletes exposed to acute and/or chronic stretching interventions. Six databases were searched (CINAHL, EMBASE, PubMed, Scopus, SPORTDiscus, and Web of Science) until 1 January 2023. The relevant data were narratively synthesized; quantitative data summaries were provided for key data items. An evidence gap map was developed to offer an overview of the existing research and relevant gaps.

RESULTS

Of ~ 220,000 screened records, we included 300 trials involving 7080 athletes [mostly males (~ 65% versus ~ 20% female, and ~ 15% unreported) under 36 years of age; tiers 2 and 3 of the Participant Classification Framework] across 43 sports. Sports requiring extreme range of motion (e.g., gymnastics) were underrepresented. Most trials assessed the acute effects of stretching, with chronic effects being scrutinized in less than 20% of trials. Chronic interventions averaged 7.4 ± 5.1 weeks and never exceeded 6 months. Most trials (~ 85%) implemented stretching within the warm-up, with other application timings (e.g., post-exercise) being under-researched. Most trials examined static active stretching (62.3%), followed by dynamic stretching (38.3%) and proprioceptive neuromuscular facilitation (PNF) stretching (12.0%), with scarce research on alternative methods (e.g., ballistic stretching). Comparators were mostly limited to passive controls, with ~ 25% of trials including active controls (e.g., strength training). The lower limbs were primarily targeted by interventions (~ 75%). Reporting of dose was heterogeneous in style (e.g., 10 repetitions versus 10 s for dynamic stretching) and completeness of information (i.e., with disparities in the comprehensiveness of the provided information). Most trials (~ 90%) reported performance-related outcomes (mainly strength/power and range of motion); sport-specific outcomes were collected in less than 15% of trials. Biomechanical, physiological, and neural/psychological outcomes were assessed sparsely and heterogeneously; only five trials investigated injury-related outcomes.

CONCLUSIONS

There is room for improvement, with many areas of research on stretching being underexplored and others currently too heterogeneous for reliable comparisons between studies. There is limited representation of elite-level athletes (~ 5% tier 4 and no tier 5) and underpowered sample sizes (≤ 20 participants). Research was biased toward adult male athletes of sports not requiring extreme ranges of motion, and mostly assessed the acute effects of static active stretching and dynamic stretching during the warm-up. Dose-response relationships remain largely underexplored. Outcomes were mostly limited to general performance testing. Injury prevention and other effects of stretching remain poorly investigated. These relevant research gaps should be prioritized by funding policies.

REGISTRATION

OSF project ( https://osf.io/6auyj/ ) and registration ( https://osf.io/gu8ya ).

Differences between 48 and 72-hour intervals on match load and subsequent recovery: a report from the Brazilian under-20 national football team

Purpose

To compare the external and internal load and subsequent recovery of football players after international tournament matches separated by 48 h vs. 72 h.

Methods

A total of 14 male football players from the Brazilian National Team, competing in the 2019 South American Under-20 Championship, participated in the study. Match load was quantified using GPS variables and perceived exertion ratings (1). Additionally, before and 13-15 h after each match, players answered questions about the number of hours and quality of sleep, recovery status, and muscle soreness (0-10) and provided a blood sample for creatine kinase and reactive C-protein analysis. Values of all variables were compared between matches played with 48-h intervals (matches 1-4) and 72-h intervals (matches 5-8).

Results

No significant differences in performance or perceptual parameters were observed between matches (p = 0.136-0.953). However, CK was higher in matches 1-4 compared to matches 5 and 6; and ΔPCR was higher in matches 2 and 3 compared to matches 5 and 6, and in match 4 compared to matches 5 and 8.

Conclusions

After matches with a 48-h rest interval, players showed increased markers of inflammation and muscle damage compared to matches with a 72-h rest interval.

Monitoring load, wellness, and psychological variables in female and male youth national team football players during international and domestic playing periods

Aim

To study differences in total load exposure, wellness, and psychological variables in youth female (N = 19) and male (N = 20) national team football players during domestic and international playing periods, respectively.

Procedures

The players filled out questionnaires on well-being, stress, and resilience before and after both playing periods lasting 8 days each. The Hooper index was used to monitor daily wellness levels during both playing periods. The number of training sessions and matches were recorded, and the session rating of perceived exertion was collected. Training load, monotony, and strain were calculated. Daily measurements were used to evaluate in-period changes, and composite scores were used to describe differences between periods.

Results

The international compared to the domestic playing period was for both groups characterized by more matches played, longer field training session durations, and of fewer gym-based sessions (P < 0.05). The male players increased total exposure time (25%; P < 0.05), monotony (P < 0.001), and strain (P < 0.001), which was not changed in the female players. Well-being decreased (P < 0.05) during the international playing period in male players. Stress levels were higher (P < 0.05) for both genders during the international compared to the domestic playing period. During the international playing period, positive correlations were found between the initial levels of stress, and the change in stress (P = 0.03; r2 = 0.12), and between the changes in total load and changes in well-being (P = 0.02; r2 = 0.12), whereas a negative correlation was found between the changes in wellness and stress (P = 0.03; r2 = 0.14).

Conclusion

A playing period characterized by increased match focus, longer field training sessions, and fewer gym-based training activities may lead to changes in the physical and mental profiles of youth national team football players. Alterations to load exposure and wellness may influence mental health. Players with high initial stress levels may be subjected to greater changes compared to other players. Sports scientists and medical staff may benefit from initiating structured monitoring systems to track alterations in physical load and mental health in youth national team players.

Monitoring Training Load and Wellness of Female Footballers Transitioning Between Club and National Teams

ABSTRACT

Brown, GA, Massard, T, Wignell, T, McCall, A, and Duffield, R. Monitoring training load and wellness of female footballers transitioning between club and national teams. J Strength Cond Res 37(11): 2235-2240, 2023-This study described the change in training and match internal loads, plus perceptual wellness during the transition between club and national teams (NTs) for female international footballers (soccer). Session count, session rating of perceived exertion (s-RPE), and perceptual wellness data were collected from 42 players from 1 NT between 2019 and 2021 for 7 NT tournaments. Data were collated into 7-day (1 week) microcycles to compare the 2 weeks before the first week of NT (transition in: NT-2, NT-1, NT1); and separately from the final NT week to the next 2 weeks in clubs (transition out: NTFinal, NT+1, NT+2). Data were analyzed using linear mixed-models, with session count, s-RPE or wellness as the outcome variable, week as the fixed effect, player name, and tournament as random effects. Tukey's adjusted post-hoc comparisons and Cohen's d effect sizes (ES) were compared between weeks. Significance level was set at p < 0.05. During the transition into NT, training and total session counts increased (p < 0.0001, ES > 0.67), training s-RPE increased (p = 0.012, ES = 0.35), whereas match count and s-RPE decreased (p < 0.05, ES < -0.34). During the transition out of NT, there were decreases in training session count (p < 0.05, ES < -0.37), match count, and total session count (p < 0.0001, ES < -0.86), and match and total s-RPE (p < 0.0001, ES < -0.63). Perceived wellness was not significantly different throughout (p > 0.05, ES = -0.34 to 0.35). Thus, training and match exposures differ between club and NTs, demonstrating these unique transitional periods require simple and effective load monitoring to inform training and recovery prescription when changing between club and NTs.

Flight Path and Scheduling Effects on Perceived Jet Lag, Fatigue, and Sleep in Footballers Traveling to and From National Teams

PURPOSE

This study examined posttravel perceptual responses of national-team footballers (soccer) following different flight paths, arrival/departure times, and trip contexts.

METHODS

Details of 396 flights from national-team players (N = 68) were obtained and verified via an online flight database. Each player provided ratings of perceptual fatigue, sleep, soreness, stress, and jet lag for 2 days before and after each trip. The flight path (continents of departure and arrival), travel context (into vs out of national team), and arrival and departure times were obtained for each trip. Linear mixed models compared the pretravel with posttravel change in perceptual responses based on flight path, context, and schedule.

RESULTS

Perceived jet-lag ratings were more responsive to travel variables (R2 = .48) than other perceptual ratings (R2 < .26). Travel from Asia to Europe (P < .05) and Europe to Australia (P < .001) had significantly higher jet-lag ratings than all other paths. Fatigue scores were worst following Asia to Europe (P < .05) and Europe to Australia (P < .05) travel, while sleep scores were worst following Europe to Australia travel (P < .01). Perceptual responses were poorer following travel from national team to club compared with all other travel contexts (P < .05). Arrival during the daytime (11 AM to 5 PM) resulted in better perceptual responses than early-morning or late-night arrivals (P < .05).

CONCLUSIONS

Perceived jet-lag ratings are more responsive to travel demands than perceptual wellness scales in national-team football athletes. Poorer perceptual responses may be expected when travel is longer in nature, ends later in the day, or involves travel out of the national team back to club.

Associations between Borg’s rating of perceived exertion and changes in urinary organic acid metabolites after outdoor weight-bearing hiking

BACKGROUND

Developing methods to monitor exercise load and evaluate body fatigue and muscle injury over time in hiking training remains a key problem to be solved. A widely used psycho-physical tool to assess the subjective perception of effort during exercise is Borg’s rating of perceived exertion (BRPE) scale. Data on the relationships and validity of the BRPE compared to objectively assessed metabolic criteria are still lacking, especially urinary organic acid concentrations.

AIM

To verify whether the BRPE scale could be used in the prescription of outdoor hiking with weight-bearing and reveal the relationship between the BRPE scale and urinary physiological measures.

METHODS

Eighty-nine healthy men (average age: 22 years) were enrolled in a 40 km (6 h) hiking training exercise with a 20 kg load. After training, the BRPE scale (6-20) was completed. All participants were divided into three groups according to the rating of the BRPE scale. Urine samples were collected before and after training. Urinary myoglobin levels were measured immediately using the fluorescent immunoassay method. The remaining urine was subpacked and frozen for the subsequent detection of urinary organic acids using gas chromatography and mass spectrometry.

RESULTS

The contents of organic acids and myoglobin in urine were significantly increased after participants hiked 40 km (6 h) with a 20 kg load. Only orthogonal partial least-squares discrimination analysis performed well in separating the group with a BRPE score of 6-12 from the group with a BRPE score of 13-20. Significant differences in the urine levels of several organic acids were observed between the two groups, and the heatmap also presented different metabolic profiles based on BRPE. According to the standard of a variable importance in the projection > 1, fold change > 1.5 and P < 0.05, 19 different metabolites of urinary organic acids were screened and enriched in pathways mainly including the citrate cycle (tricarboxylic acid cycle) and alanine, aspartate and glucose metabolism.

CONCLUSION

The BRPE scale identified significantly different urinary organic acid profiles between the higher and lower BRPE value groups, and, thus, could be used to monitor body fatigue in individuals participating in long-distance outdoor hiking with weight bearing.

Travel Across More Time Zones Results in Worse Perceived Fatigue and Sleep in National-Team Footballers

PURPOSE

This study investigated the association between (1) time zone difference and (2) travel direction (east vs west) with posttravel changes in perceptual responses of national-team footballers.

METHODS

Travel schedules from 355 national-team trips (50 elite soccer players) were verified using an online flight database. All players provided perceptual ratings of fatigue, sleep quality, soreness, and stress to calculate changes in scores up to 2 days after travel. Trips were categorized as <3, 3 to 6, 6 to 9, or 9+ time zone changes, along with travel direction (eastward or westward). The pretravel to posttravel changes in perceptual ratings at days 1 and 2 postarrival were compared between time zone change and travel direction with linear mixed models.

RESULTS

For every time zone crossed, poorer ratings of perceptual fatigue (β = 0.068, P < .001), sleep (β = 0.095, P < .001), soreness (β = 0.0049, P < .001), and total wellness (β = 0.214, P < .001) were observed. However, the models explained only small proportions of the variation in postflight perceptual responses (7%-18%). Regardless, travel across 9+ time zones resulted in significantly worse perceived fatigue, sleep, and total wellness for days 1 and 2 postarrival compared with travel with <6 time zones (P < .05). Additionally, fatigue, sleep, and total scores were worse on day 2 following trips of 9+ time zones. Eastward travel resulted in poorer sleep ratings (β = 0.52, P < .001) than westward travel within time zone groupings.

CONCLUSIONS

Perceptual ratings of fatigue and sleep become progressively worse as travel increases in national-team soccer players, especially after travel across 9+ time zones and eastward travel.

Biomarkers of post-match recovery in semi-professional and professional football (soccer)

High-level football (soccer) players face intense physical demands that result in acute and residual fatigue, impairing their physical performance in subsequent matches. Further, top-class players are frequently exposed to match-congested periods where sufficient recovery times are not achievable. To evaluate training and recovery strategies, the monitoring of players' recovery profiles is crucial. Along with performance and neuro-mechanical impairments, match-induced fatigue causes metabolic disturbances denoted by changes in chemical analytes that can be quantified in different body fluids such as blood, saliva, and urine, thus acting as biomarkers. The monitoring of these molecules might supplement performance, neuromuscular and cognitive measurements to guide coaches and trainers during the recovery period. The present narrative review aims to comprehensively review the scientific literature on biomarkers of post-match recovery in semi-professional and professional football players as well as provide an outlook on the role that metabolomic studies might play in this field of research. Overall, no single gold-standard biomarker of match-induced fatigue exists, and a range of metabolites are available to assess different aspects of post-match recovery. The use of biomarker panels might be suitable to simultaneously monitoring these broad physiological processes, yet further research on fluctuations of different analytes throughout post-match recovery is warranted. Although important efforts have been made to address the high interindividual heterogeneity of available markers, limitations inherent to these markers might compromise the information they provide to guide recovery protocols. Further research on metabolomics might benefit from evaluating the long-term recovery period from a high-level football match to shed light upon new biomarkers of post-match recovery.

Congested Period in Professional Youth Soccer Players Showed a Different High Decelerations Profile in the Group Performance and a Specific Positional Behaviour

Present soccer demands are increasing in terms of running requirements and the number of matches until youth soccer players experience several periods of fixture congestion during the season. Currently, congested periods have not been extensively studied in this population. For this reason, this study aimed to compare the running demands of professional youth soccer players in congested periods according to their specific playing positions. Twenty youth players were grouped according to their position: Central Defenders (CD), Fullbacks (FB), Midfielders (MF), Wide Midfielders (WM) and Strikers (ST). A GPS system was used to monitor the players during the first (M1), second (M2) and third (M3) matches played during a congested period, measuring their total distance covered (TDC), DC 18.0−20.9 km·h−1, DC 21.0−23.9 km·h−1, DC > 24.0 km·h−1, number of high accelerations (>2.5 m·s−2), number of high decelerations (<2.5 m·s−2) and peak speed (km·h−1). M1, M2 and M3 showed the same TDC, DC 18.0−20.9 km·h−1, DC 21.0−23.9 km·h−1, DC > 24.0 km·h−1, number of high accelerations, and peak speed (p > 0.05). The statistical analysis showed significant differences between M1, M2 and M3 in the decelerations recorded between M1 and M3 (p < 0.05). Likewise, each position showed specific behaviours during the congested period, with all showing at least one difference in DC 18.0−20.9 km·h−1, 21.0−23.9 km·h−1 or >24.0 km·h−1 between M1, M2 and M3 (p < 0.05). In conclusion, coaches should pay attention to the fatigue produced by the number of high decelerations. Secondly, an individualized training protocol should be considered according to the running requirements of each position when youth professional soccer players are involved in a congested period.