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Travel Across More Time Zones Results in Worse Perceived Fatigue and Sleep in National-Team Footballers
Abstract
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.
... It is important to consider that in international competitions, players are exposed to training and match demands that differ from their club routines [6], which may lead to high variability in neuromuscular responses between players. Additionally, external factors such as the menstrual cycle and time zone adaptation can further influence training load, neuromuscular performance and perceptual responses [7,8]. Therefore, transition periods from a club to a national team require simple and effective load monitoring to guide training strategies and optimize Individual changes in neuromuscular performance in the Spanish women's national football team throughout the 2023 World Cup accuracy, reliability, and sensitivity in detecting fatigue and adaptations in programming training for football players [19]. ...
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.
Purpose:
This study examined the relationship of prematch travel and in-camp training on ensuing physical and technical match performance of footballers (soccer) competing for a national team.
Methods:
Match running and technical performance data were obtained from 68 national-team footballers competing in international matches (N = 108). Match performance data were aligned with the confirmed travel durations, time-zone change, travel direction, and time between arrival and kickoff for the travel to the match. In addition, in-camp training load from the 3 days prior to national-team matches was also collated. Linear mixed models assessed relationships between travel and training measures with physical and technical match performance outcomes.
Results:
Travel variables explained little variance in outcomes (R2 = .02-.16). Traveling eastward was associated with an increase in total (P = .042) and very high-speed distance (P = .030) in matches and a 5% decrease in pass accuracy (P = .012). Greater time-zone difference was associated with increased match decelerations (P = .027), while arriving later for matches was associated with increased total (P = .041) tackles. Increases in training high-speed distance were associated with increases in match high-speed distance (P = .004) and number of decelerations (P < .001). An increase in training total distance was associated with a decrease in match decelerations (P = .002).
Conclusions:
Prematch travel appeared to have minimal effects on physical and technical performance in this national team. Training loads prior to matches may have some relationship with match running performance, and, thus, readiness to train should be a priority for athletes arriving in national-team camps.
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.
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.
Athletes are increasingly required to travel domestically and internationally, often resulting in travel fatigue and jet lag. Despite considerable agreement that travel fatigue and jet lag can be a real and impactful issue for athletes regarding performance and risk of illness and injury, evidence on optimal assessment and management is lacking. Therefore 26 researchers and/or clinicians with knowledge in travel fatigue, jet lag and sleep in the sports setting, formed an expert panel to formalise a review and consensus document. This manuscript includes definitions of terminology commonly used in the field of circadian physiology, outlines basic information on the human circadian system and how it is affected by time-givers, discusses the causes and consequences of travel fatigue and jet lag, and provides consensus on recommendations for managing travel fatigue and jet lag in athletes. The lack of evidence restricts the strength of recommendations that are possible but the consensus group identified the fundamental principles and interventions to consider for both the assessment and management of travel fatigue and jet lag. These are summarised in travel toolboxes including strategies for pre-flight, during flight and post-flight. The consensus group also outlined specific steps to advance theory and practice in these areas.
Rossiter, A, Warrington, GD, and Comyns, TM. Effects of long-haul travel on recovery and performance in elite athletes: a systematic review. J Strength Cond Res 36(11): 3234-3245, 2022-Elite athletes are often required to travel long-haul (LH) across numerous time zones for training or competition. However, the extent to which LH travel affects elite athlete performance remains largely unknown. The purpose of this systematic literature review was to critically evaluate available evidence on the effects of LH travel on elite athlete psychometric, physiological, sleep, and performance markers. Electronic database searches of PubMed, SPORTDiscus, Scopus, and Web of Science were conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies were eligible for inclusion if subjects were identified as elite athletes who embarked on a LH flight (>6 hours) and used an outcome measurement of recovery or performance after the flight. Studies that were retrospective, used light therapy or pharmacological interventions were not included. Of 2,719 records assessed, 14 studies comprising a total of 197 athletes from 6 sports met the inclusion criteria. There was an increase in perceived jet lag and disturbance to various physiological markers after LH travel; however, there was minimal disturbance in other psychometric markers. Sleep was not negatively affected by LH travel. Of 10 studies that assessed performance, 3 found decrements in indirect markers of performance. Elite athletes perceived themselves to be jet lagged and experienced disturbance to various physiological mechanisms after LH travel; however, the effect on performance was inconclusive. Future research would benefit from higher quality studies with improved control measures, larger sample sizes from a wider variety of sports, and use of ecologically valid measures of circadian rhythm and athletic performance.
Purpose:
To assess the efficacy of a combined light exposure and sleep hygiene intervention to improve team-sport performance following eastward long-haul transmeridian travel.
Methods:
Twenty physically trained males underwent testing at 09:00 and 17:00 hours local time on 4 consecutive days at home (baseline) and the first 4 days following 21 hours of air travel east across 8 time zones. In a randomized, matched-pairs design, participants traveled with (INT; n = 10) or without (CON; n = 10) a light exposure and sleep hygiene intervention. Performance was assessed via countermovement jump, 20-m sprint, T test, and Yo-Yo Intermittent Recovery Level 1 tests, together with perceptual measures of jet lag, fatigue, mood, and motivation. Sleep was measured using wrist activity monitors in conjunction with self-report diaries.
Results:
Magnitude-based inference and standardized effect-size analysis indicated there was a very likely improvement in the mean change in countermovement jump peak power (effect size 1.10, ±0.55), and likely improvement in 5-m (0.54, ±0.67) and 20-m (0.74, ±0.71) sprint time in INT compared with CON across the 4 days posttravel. Sleep duration was most likely greater in INT both during travel (1.61, ±0.82) and across the 4 nights following travel (1.28, ±0.58) compared with CON. Finally, perceived mood and motivation were likely worse (0.73, ±0.88 and 0.63, ±0.87) across the 4 days posttravel in CON compared with INT.
Conclusions:
Combined light exposure and sleep hygiene improved speed and power but not intermittent-sprint performance up to 96 hours following long-haul transmeridian travel. The reduction of sleep disruption during and following travel is a likely contributor to improved performance.
Objectives
We investigated the management of travel fatigue and jet lag in athlete populations by evaluating studies that have applied non-pharmacological interventions (exercise, sleep, light and nutrition), and pharmacological interventions (melatonin, sedatives, stimulants, melatonin analogues, glucocorticoids and antihistamines) following long-haul transmeridian travel-based, or laboratory-based circadian system phase-shifts.
Design
Systematic review
Eligibility criteria
Randomised controlled trials (RCTs), and non-RCTs including experimental studies and observational studies, exploring interventions to manage travel fatigue and jet lag involving actual travel-based or laboratory-based phase-shifts. Studies included participants who were athletes, except for interventions rendering no athlete studies, then the search was expanded to include studies on healthy populations.
Data sources
Electronic searches in PubMed, MEDLINE, CINAHL, Google Scholar and SPORTDiscus from inception to March 2019. We assessed included articles for risk of bias, methodological quality, level of evidence and quality of evidence.
Results
Twenty-two articles were included: 8 non-RCTs and 14 RCTs. No relevant travel fatigue papers were found. For jet lag, only 12 athlete-specific studies were available (six non-RCTs, six RCTs). In total (athletes and healthy populations), 11 non-pharmacological studies (participants 600; intervention group 290; four non-RCTs, seven RCTs) and 11 pharmacological studies (participants 1202; intervention group 870; four non-RCTs, seven RCTs) were included. For non-pharmacological interventions, seven studies across interventions related to actual travel and four to simulated travel. For pharmacological interventions, eight studies were based on actual travel and three on simulated travel.
Conclusions
We found no literature pertaining to the management of travel fatigue. Evidence for the successful management of jet lag in athletes was of low quality. More field-based studies specifically on athlete populations are required with a multifaceted approach, better design and implementation to draw valid conclusions.
PROSPERO registration number
The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO: CRD42019126852).
Introduction: Long-haul transmeridian travel is known to cause disruptions to sleep and immune status, which may increase the risk of illness.
Aim: This study aimed to determine the effects of long-haul northeast travel for competition on sleep, illness and preparedness in endurance athletes.
Methods: Twelve trained (13.8 ± 3.2 training h/week) masters (age: 48 ± 14 years) triathletes were monitored for sleep (quantity via actigraphy and quality via self-report), mucosal immunity (salivary immunoglobulin-A) and stress (salivary cortisol) as well as self-reported illness, fatigue, recovery and preparedness. Baseline measures were recorded for 2 weeks prior to travel for all variables except for the saliva samples, which were collected on three separate days upon waking. Participants completed normal training during the baseline period. Measures were subsequently recorded before, during and after long-haul northeast travel from the Australian winter to the Hawaiian summer, and in the lead up to an Ironman 70.3 triathlon.
Results: All comparisons are to baseline. There was a most likely decrease in sleep duration on the over-night flight (-4.8 ± 1.2 h; effect size; ±90% confidence limits = 3.06; ±1.26) and a very likely increase in sleep duration on the first night after arrival (0.7 ± 1.0 h; 1.15; ±0.92). After this time, sleep duration returned to baseline for several days until it was very likely decreased on the night prior to competition (-1.2 ± 1.0 h; 1.18; ±0.93). Nap duration was likely increased on the first day after arrival (36 ± 65 min; 3.90; ±3.70). There was also a likely increase in self-reported fatigue upon waking after the first night in the new destination (1.1 ± 1.6 AU; 0.54; ±0.41) and there were three athletes (25%) who developed symptoms of illness 3–5 days after arrival. There were no changes in sleep quality or mucosal measures across study.
Discussion: Long-haul northeast travel from a cool to a hot environment had substantial influences on sleep and self-reported fatigue, but these alterations had returned to pre-departure baseline 48 h after arrival. Endurance athletes undertaking similar journeys may benefit from optimizing sleep hygiene, especially on the first 2 days after arrival, or until sleep duration and fatigue levels return to normal.
Purpose:
The aim of this study was to assess post-match perceived exertion, feeling and wellness according to the match outcome (winning, drawing or losing) in professional soccer players.
Methods:
Twelve outfield players were followed during 52 official matches where the outcomes (win, draw or lose) were noted. Following each match players completed both a 10-point scale rating of perceived exertion (RPE) and an 11-point scale rating of perceived feeling. Rating of perceived sleep quality, stress, fatigue and muscle soreness were collected separately on a 7-point scale the day following each match.
Results:
Player RPE was higher by a very largely magnitude following a loss compared to a draw or a win and higher by a small magnitude after a draw compared to a win. Players felt more pleasure after a win compared to a draw or loss and more displeasure after a loss compared to draw. The players reported a largely and moderately better-perceived sleep quality, less stress and fatigue following a win compared to draw or a loss, and a moderately bad-perceived sleep quality, higher stress and fatigue following a draw compared to a loss. In contrast, only a trivial-small change was observed in perceived muscle soreness between all outcomes.
Conclusion:
Matches outcomes moderately to largely affect RPE, perceived feeling, sleep quality, stress and fatigue whereas perceived muscle soreness remains high regardless of the match outcome. However, winning a match decreases the strain and improves both pleasure and wellness in professional soccer players.
Currently, very little is known about the impact of short- or long-haul air travel on the sleep and wellbeing of wheelchair basketball athletes. Eleven national wheelchair basketball athletes wore actigraphy monitors prior, during, and after air travel to the United Kingdom. Upon arrival, participants rated their subjective jet-lag, fatigue, and vigor. Individuals traveled to the United Kingdom from different locations in Australia, the United States, and Europe and were categorised according to travel length [LONG (up to 30.2 h) or SHORT (up to 6.5 h)]. Linear mixed models determined effects of travel length on sleep and subjective ratings of jet-lag, fatigue, and vigor. During competition, subjective fatigue and jet-lag were substantially higher (ES = 0.73; ±0.77) and (ES = 0.57; ±0.60), subjective vigor was lower (ES = 1.94; ±0.72), and get-up time was earlier (ES = 0.57; ±0.60) for LONG when compared to SHORT. Travelling greater distances by airplane had a larger effect on subjective ratings of jet-lag, fatigue and vigor, rather than sleep. Irrespective of travel group, sleep and subjective responses were compromised, reflecting the travel requirements, competition-mediated influences, and/or due to a change in environment.
Purpose:
Determine the recovery timeline of sleep, subjective jet-lag and fatigue, and team-sport physical performance following east and west long-haul travel.
Methods:
Ten, physically-trained males underwent testing at 09:00 (AM) and 17:00 (PM) local time on four consecutive days two weeks prior to outbound travel (BASE), and the first four days following 21 h of outbound (WEST) and return (EAST) air travel across eight time-zones between Australia and Qatar. Data collection included performance (countermovement jump [CMJ], 20-m sprint and Yo-Yo Intermittent Recovery level 1 [YYIR1] test) and perceptual (jet-lag, motivation, perceived exertion and physical feeling) measures. In addition, sleep was measured via wrist activity monitors and self-report diaries throughout the aforementioned data collection periods.
Results:
Compared to the corresponding day at BASE, the reduction in YYIR1 distance following EAST was significantly different to the increase WEST on day 1 post-travel (p<0.001). On day 2, significantly slower 20-m sprint times were detected in EAST compared to WEST (p=0.03), with large effect sizes also indicating a greater reduction in YYIR1 distance in EAST compared to WEST (d=1.06). Mean sleep onset and offset were significantly later and mean time in bed and sleep duration were significantly reduced across the four days in EAST compared to BASE and WEST (p<0.05). Lastly, mean jet-lag, fatigue and motivation ratings across the four days were significantly worse in EAST compared to BASE and WEST (p<0.05), and WEST compared to BASE (p<0.05).
Conclusions:
Long-haul transmeridian travel can impede team-sport physical performance. Specifically, travel east has a greater detrimental effect on sleep, subjective jet-lag, fatigue and motivation. Consequently, maximal- and intermittent-sprint performance is also reduced following travel east, particularly within 72 h following arrival.
Objectives
Describe the effects of eastward long-haul transmeridian air travel on subjective jet-lag, sleep and wellness in professional football (soccer) players prior to the 2014 FIFA World Cup in Brazil.
Design
Single cohort involving twenty-three male professional football players representing a national football team.
Methods
Data was collected from players prior to and following international travel from Sydney, Australia to Vitoria, Brazil. In total there were three flights, 19-h and 14,695 km of travel east across 11 time-zones. Training load and wellness measures were obtained in the week prior to and following travel, whilst sleep and jet-lag measures were collected on the day prior to travel (Pre), the day of arrival and for five days following travel (Post 1 to 5).
Results
Compared to Pre, perceived jet-lag was significantly increased on Post 1 to 4, with significantly greater levels on Post 1 compared to Post 5 (p < 0.05). Self-reported sleep duration during travel was 5.9 (4.8-7.0) h, which was significantly lower than all other nights (p˂0.01), except for the night of arrival, where time in bed and sleep duration were significantly reduced compared to Post 1, 2, 3 and 4 (p˂0.01). Lastly, compared to the week prior to travel, mean wellness was significantly reduced during the week following travel (p˂0.01).
Conclusions
Self-reported sleep disruption during and following eastward long-haul transmeridian air travel, together with exacerbated jet-lag symptoms may result in reduced player wellness. Consequently, player preparedness for subsequent training and competition may be impeded, though physical performance data is lacking.
Purpose:
To examine the effects of 24-h travel west across 11 time zones on subjective jet-lag and wellness responses together with self-reported sleep and upper respiratory symptoms in 18 professional rugby league players.
Methods:
Measures were obtained 1 or 2 d before (pretravel) and 2, 6, and 8 d after travel (post-2, post-6, and post-8) from Australia to the United Kingdom (UK) for the 2015 World Club Series.
Results:
Compared with pretravel, subjective jet-lag remained significantly elevated on post-8 (3.1 ± 2.3, P < .05, d > 0.90), although it was greatest on post-2 (4.1 ± 1.4). Self-reported sleep-onset times were significantly earlier on post-2 than at all other time points (P < .05, d > 0.90), and large effect sizes suggested that wake times were earlier on post-2 than on post-6 and post-8 (d > 0.90). Although significantly more upper respiratory symptoms were reported on post-6 than at pretravel (P < .05, d ˃ 0.90), no incidence of injury and negligible changes in wellness and muscle strength and range of motion (P > .05, d < 0.90) were evident after travel.
Conclusions:
Results suggest that westward long-haul travel between Australia and the UK exacerbates subjective jet-lag and sleep responses, along with upper respiratory symptoms, in professional rugby league players. Of note, the increase in self-reported upper respiratory symptoms is a reminder that the demands of long-haul travel may be an additional concern in jet-lag for traveling athletes. However, due to the lack of sport-specific performance measures, it is still unclear whether international travel interferes with training to the extent that subsequent competition performance is impaired.
The present study examined the sleep, travel and recovery responses of elite footballers during and following long-haul international air travel, with a further description of these responses over the ensuing competitive tour (including two matches).
In an observational design, 15 elite male football players undertook 18 h of predominately westward international air travel from the United Kingdom to South America (-4 h time-zone shift) for a 10-day tour. Objective sleep parameters, external and internal training loads, subjective player match performance, technical match data and perceptual jet-lag and recovery measures were collected.
Significant differences were evident between outbound travel and recovery night 1 (night of arrival; P<0.001) for sleep duration. Sleep efficiency was also significantly reduced during outbound travel compared to recovery nights 1 (P=0.001) and 2 (P=0.004). Furthermore, both match nights (5 and 10), showed significantly less sleep than non-match nights 2-4 and 7-9 (all P<0.001). No significant differences were evident between baseline and any time point for all perceptual measures of jet-lag and recovery (P>0.05); although large effects were evident for jet-lag on Day 2 (two days after arrival).
Sleep duration is truncated during long-haul international travel with a 4 h time-zone delay, and following night matches in elite footballers. However this lost sleep appeared to have a limited effect on perceptual recovery, which may be explained by a westbound flight and a relatively small change in time-zones, in addition to the significant increase in sleep duration on the night of arrival following the long-haul flight.
The available scientific research regarding injury prevention practices in international football is sparse. The purpose of this study was to quantify current practice with regard to (1) injury prevention of top-level footballers competing in an international tournament, and (2) determine the main challenges and issues faced by practitioners in these national teams.
A survey was administered to physicians of the 32 competing national teams at the FIFA 2014 World Cup. The survey included 4 sections regarding perceptions and practices concerning non-contact injuries: (1) risk factors, (2) screening tests and monitoring tools, (3) preventative strategies and (4) reflection on their experience at the World Cup.
Following responses from all teams (100%), the present study revealed the most important intrinsic (previous injury, accumulated fatigue, agonist:antagonist muscle imbalance) and extrinsic (reduced recovery time, training load prior to and during World Cup, congested fixtures) risk factors during the FIFA 2014 World Cup. The 5 most commonly used tests for risk factors were: flexibility, fitness, joint mobility, balance and strength; monitoring tools commonly used were: medical screen, minutes/matches played, subjective and objective wellness, heart rate and biochemical markers. The 5 most important preventative exercises were: flexibility, core, combined contractions, balance and eccentric.
The present study showed that many of the National football (soccer) teams' injury prevention perceptions and practices follow a coherent approach. There remains, however, a lack of consistent research findings to support some of these perceptions and practices.
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To quantify the relationship between daily training load and a range of potential measures of fatigue in elite soccer players during an in-season competitive phase (17-days).
Total high-intensity running distance (THIR), perceived ratings of wellness (fatigue, muscle soreness, sleep quality), counter-movement jump height (CMJ), post-exercise heart rate recovery (HRR) and heart rate variability (Ln rMSSD) were analysed during an in-season competitive period (17 days). General linear models were used to evaluate the influence of daily fluctuation in THIR distance on potential fatigue variables.
Fluctuations in fatigue (r=-0.51; large; P<0.001), Ln rMSSD (r=-0.24; small; P=0.04), and CMJ (r=0.23; small; P=0.04) were significantly correlated with fluctuations in THIR distance. Correlations between variability in muscle soreness, sleep quality and HRR and THIR distance were negligible and not statistically significant.
Perceived ratings of fatigue and heart rate variability were sensitive to daily fluctuations in THIR distance in a sample of elite soccer players. Therefore, these particular markers show particular promise as simple, non-invasive assessments of fatigue status in elite soccer players during a short in-season competitive phase.
The current study examined the acute and longitudinal effects of regular away travel on training load (TL), player wellness, and injury surrounding competitive football (soccer) matches. Eighteen male professional football players, representing a team competing in the highest national competition in Australia, volunteered to participate in the study. Training loads, player wellness and injury incidence, rate, severity, and type, together with the activity at the time of injury, were recorded on the day before, the day of, and for 4 d after each of the 27 matches of the 2012-13 season. This included 14 home and 13 away matches, further subdivided based on the midpoint of the season into early (1-13) and late competition (14-27) phases. While TLs were significantly greater on day 3 at home compared with away during the early competition phase (P=.03), no other significant effects of match location were identified (P>.05). Total TL and mean wellness over the 6 d surrounding matches and TL on day 3 were significantly reduced during the late compared with the early competition phase at home and away (P<.05). Although not significantly (P>.05), training missed due to injury was 60% and 50% greater during the late than during the early competition phase at home and away, respectively. In conclusion, no significant interactions between match location and competition phase were evident during the late competition phase, which suggests that away travel had negligible cumulative effects on the reduction in player wellness in the latter half of the season.
Purpose
Despite the reported detrimental effects of international air travel on physical performance, a paucity of interventions have been scientifically tested and confirmed to benefit travelling athletes. Consequently, the aim of the present study was to examine the effects of sleep hygiene and artificial bright light interventions on physical performance following simulated international travel.
Methods
In a randomized crossover design, 13 physically active males completed 24 h of simulated international travel with (INT) and without (CON) the interventions. The mild hypoxia and cramped conditions typically encountered during commercial air travel were simulated in a normobaric, hypoxic room. Physical performance, subjective jet-lag symptoms and mood states were assessed in the morning and evening on the day prior to and for two days post-travel. Sleep quantity and quality were monitored throughout each trial.
Results
Sleep duration was significantly reduced during travel in both trials (P 0.05). Furthermore, vigour was significantly greater (P = 0.04) the morning of day 2 in INT [5.3 (3.9–6.7)] compared to CON [2.8 (1.4–4.2)], and subjective jet-lag symptoms and mood states were significantly worse on day 2 in CON only (P
Maximum likelihood or restricted maximum likelihood (REML) estimates of the
parameters in linear mixed-effects models can be determined using the lmer
function in the lme4 package for R. As for most model-fitting functions in R,
the model is described in an lmer call by a formula, in this case including
both fixed- and random-effects terms. The formula and data together determine a
numerical representation of the model from which the profiled deviance or the
profiled REML criterion can be evaluated as a function of some of the model
parameters. The appropriate criterion is optimized, using one of the
constrained optimization functions in R, to provide the parameter estimates. We
describe the structure of the model, the steps in evaluating the profiled
deviance or REML criterion, and the structure of classes or types that
represents such a model. Sufficient detail is included to allow specialization
of these structures by users who wish to write functions to fit specialized
linear mixed models, such as models incorporating pedigrees or smoothing
splines, that are not easily expressible in the formula language used by lmer.
The current study examined the effects of short-haul air travel on competition performance and subsequent recovery. Six male professional Australian football (soccer) players were recruited to participate in the study. Data were collected from 12 matches, which included 6 home and away matches against the same 4 teams. Together with the outcome of each match, data were obtained for team technical and tactical performance indicators and individual player-movement patterns. Furthermore, sleep quantity and quality, hydration, and perceptual fatigue were measured 2 days before, the day of, and 2 days after each match. More competition points were accumulated (P > .05, d = 1.10) and fewer goals were conceded (P > .05, d = 0.93) in home than in away matches. Furthermore, more shots on goal (P > .05, d = 1.17) and corners (P > .05, d = 1.45) and fewer opposition shots on goal (P > .05, d = 1.18) and corners (P < .05, d = 2.32) occurred, alongside reduced total distance covered (P > .05, d = 1.19) and low-intensity activity (P < .05, d = 2.25) during home than during away matches. However, while oxygen saturation was significantly lower during than before and after outbound and return travel (P < .01), equivocal differences in sleep quantity and quality, hydration, and perceptual fatigue were observed before and after competition away compared with home. These results suggest that, compared with short-haul air travel, factors including situational variables, territoriality, tactics, and athlete psychological state are more important in determining match outcome. Furthermore, despite the potential for disrupted recovery patterns, return travel did not impede player recovery or perceived readiness to train.
The present study examined effects of simulated air travel on physical performance. In a randomized crossover design, 10 physically active males completed a simulated 5-h domestic flight (DOM), 24-h simulated international travel (INT), and a control trial (CON). The mild hypoxia, seating arrangements, and activity levels typically encountered during air travel were simulated in a normobaric, hypoxic altitude room. Physical performance was assessed in the afternoon of the day before (D − 1 PM) and in the morning (D + 1 AM) and afternoon (D + 1 PM) of the day following each trial. Mood states and physiological and perceptual responses to exercise were also examined at these time points, while sleep quantity and quality were monitored throughout each condition. Sleep quantity and quality were significantly reduced during INT compared with CON and DOM (P < 0.01). Yo-Yo Intermittent Recovery level 1 test performance was significantly reduced at D + 1 PM following INT compared with CON and DOM (P < 0.01), where performance remained unchanged (P > 0.05). Compared with baseline, physiological and perceptual responses to exercise, and mood states were exacerbated following the INT trial (P < 0.05). Attenuated intermittent-sprint performance following simulated international air travel may be due to sleep disruption during travel and the subsequent exacerbated physiological and perceptual markers of fatigue.
Jet lag has potentially serious deleterious effects on performance in athletes following transmeridian travel, where time zones are crossed eastwards or westwards; as such, travel causes specific effects related to desynchronization of the athlete's internal body clock or circadian clock. Athletes are particularly sensitive to the effects of jet lag, as many intrinsic aspects of sporting performance show a circadian rhythm, and optimum competitive results require all aspects of the athlete's mind and body to be working in tandem at their peak efficiency. International competition often requires transmeridian travel, and competition timings cannot be adjusted to suit individual athletes. It is therefore in the interest of the individual athlete and team to understand the effects of jet lag and the potential adaptation strategies that can be adopted. In this review, we describe the underlying genetic and physiological mechanisms controlling the circadian clock and its inherent ability to adapt to external conditions on a daily basis. We then examine the fundamentals of the various adaptation stimuli, such as light, chronobiotics (e.g. melatonin), exercise, and diet and meal timing, with particular emphasis on their suitability as strategies for competing athletes on the international circuit. These stimuli can be artificially manipulated to produce phase shifts in the circadian rhythm to promote adaptation in the optimum direction, but care must be taken to apply them at the correct time and dose, as the effects produced on the circadian rhythm follow a phase-response curve, with pronounced shifts in direction at different times. Light is the strongest realigning stimulus and careful timing of light exposure and avoidance can promote adjustment. Chronobiotics such as melatonin can also be used to realign the circadian clock but, as well as timing and dosage issues, there are also concerns as to its legal status in different countries and with the World Anti-Doping Agency. Experimental data concerning the effects of food intake and exercise timing on jet lag is limited to date in humans, and more research is required before firm guidelines can be stated. All these stimuli can also be used in pre-flight adaptation strategies to promote adjustment in the required direction, and implementation of these is described. In addition, the effects of individual variability at the behavioural and genetic levels are also discussed, along with the current limitations in assessment of these factors, and we then put forward three case studies, as examples of practical applications of these strategies, focusing on adaptations to travel involving competition in the Rugby Sevens World Cup and the 2016 Summer Olympics in Rio de Janeiro, Brazil. Finally, we provide a list of practice points for optimal adaptation of athletes to jet lag.
It is perceived that long haul travel, comprising of rapid movement across several time zones is detrimental to performance in elite athletes. However, available data is equivocal on the impact of long haul travel on maximal explosive movements. The aim of this study was to quantify the impact of long haul travel on lower body muscle performance. Five elite Australian skeleton athletes (1 M, 4 F) undertook long haul flight from Australia to Canada (LH(travel)), while seven national team Canadian skeleton athletes (1 M, 6 F) acted as controls (NO(travel)). Lower body power assessments were performed once per day between 09:30 and 11:00 h local time for 11 days. Lower body power tests comprised of box drop jumps, squat jump (SJ) and countermovement jumps (CMJ). The LH(travel) significantly decreased peak and mean SJ velocity but not CMJ velocity in the days following long haul flight. CMJ height but not SJ height decreased significantly in the LH(travel) group. The peak velocity, mean velocity and jump power eccentric utilisation ratio for the LH(travel) group all significantly increased 48 h after long haul flight. Anecdotally athletes perceived themselves as 'jet-lagged' and this corresponded with disturbances observed in 'one-off' daily jumping ability between 09:30 and 11:00 h after eastward long haul travel from Australia to North America when compared to non-travel and baseline controls.
In healthy male top athletes several functions were measured after either a westbound flight over six time-zones (WEST: Frankfurt-Atlanta; n = 13) or an eastbound flight over eight time-zones (EAST: Munich-Osaka; n = 6). Under either condition the athletes performed two standardized exercise training units in the morning and in the afternoon within 24 h, investigations were done as controls in Germany and on day 1, 4, 6, and 11, after arrival. The primary aim of the study was to evaluate the effect of time-zone transitions on the 24h profiles of blood pressure (BP) and heart rate (HR) using an ambulatory BP device (SpaceLabs 90207), for up to 11 d after arrival at the destination. As additional parameters, we studied jet-lag symptoms, training performance, and training coordination by using visual analog scales. Finally, oral temperature and grip strength were measured, and saliva samples were analyzed for cortisol and melatonin. The study showed that all functions were disturbed on the first day after arrival at the destination, jet-lag symptoms remained until day 5-6 after WEST and day 7 after EAST, training performance was worst within the first 4 d after WEST. In accordance with earlier reports, cortisol, melatonin, body temperature, and grip strength were affected in their 24h profiles and additionally modified by the training units. Surprisingly, BP and HR were not only affected on the first day but also the time-zone transition led to an increase in BP after WEST and a decrease in BP after EAST. However, the training units seemed to influence the BP profile more than the time-zone transitions. HR rhythm was affected by both time-zone transitions and exercise. It is concluded that not only jet-lag symptoms but also alterations in physiological functions should be considered to occur in highly competitive athletes due to time-zone transition and, therefore, an appropriate time of reentrainment is recommended.
Objectives
To describe the perceived load, fatigue and recovery profiles during congested and non-congested schedules in international football tournaments.
Design
Retrospective single-cohort observational study
Methods
Internal load (session-rating of perceived exertion [s-RPE]) and perceived ratings of fatigue, muscle soreness, psychological status, sleep quality, and sleep duration were recorded daily from 37 national team footballers during the competition phase of 3 international tournaments. ANOVA and Effect Size (ES) analyses compared individualised internal load and perceived response profiles between congested and non-congested acute 2-match schedules. Conditions included Acute Congestion (≤4 days between two matches), Non-Congestion (> 4 days between two matches), Single-Match, and No-Match.
Results
Significantly higher s-RPE match loads (p<0.001) within the single- and multi-match conditions resulted in significantly worsened (p<0.05) subjective ratings of perceived fatigue, muscle soreness and sleep duration in the 24-48h post-match. Internal load profiles were not different between the Acute-Congestion or Non-congestion conditions (p>0.05); though Acute-Congestion had significantly worsened pre-match subjective ratings compared to Non-Congestion on both MD1 (p = 0.040; ES = 0.94) and MD2 (p = 0.033; ES = 0.94). However, between-match differences in Acute-Congestion showed no further impairments in perceived response between the first and second matches (p>0.05).
Conclusion
During international tournaments, internal load and perceived fatigue/recovery profiles are largely determined by their exposure (or lack thereof) to match-play. Periods of acute match congestion impaired players pre-match perceived status when compared to non-congested microcycles. However, acute match congestion does not appear to exacerbate players post-match fatigue/recovery response within the context of international football tournaments.
There is a scarcity of research examining the effects of long-distance transmeridian travel (LDTT) on the sleep and match performance of team sport players. To address this, 37 elite male rugby union players from a Super Rugby team undertaking LDTT were recruited. The participants completed validated sleep questionnaires and wore a wrist-worn activity monitor (Readiband™) during a Super Rugby season (including during periods of LDTT crossing 5, 6, and 13 time-zones) to ascertain objective measures of sleep. Sleep measures were compared using mixed model analysis to ascertain the effects of competition and LDTT on sleep. Total sleep time (TST) increased in the days prior to matches, and decreased following matches (accompanied by a later time at sleep onset), particularly when next-day early-morning flights were required. TST was decreased when sleep was attempted during LDTT, except for in the last travel bout where players napped in addition to achieving night-time sleep. TST was also reduced for the night immediately following LDTT, except for in Condition 3 where players delayed wake time and also achieved naps. This study exemplifies the challenges that team-sport athletes face in obtaining regular sleep when LDTT is required.
Background:
Athlete-reported outcome measures (AROMs) are frequently used in research and practice but no studies have examined their psychometric properties.
Objectives:
Part 1-identify the most commonly used AROMs in sport for monitoring training responses; part 2-assess risk of bias, measurement properties, and level of evidence, based on the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidelines.
Study appraisal and synthesis methods:
Methodological quality of the studies, quality of measurement properties, and level of evidence were determined using the COSMIN checklist and criteria.
Results:
Part 1-from 9446 articles screened for title and abstract, 310 out of 334 full texts were included; 53.9% of the AROMs contained multiple items, while 46.1% contained single items. Part 2-from 1895 articles screened for title and abstract, 71 were selected. Most measurement properties of multiple-item AROMs were adequate, but content validity and measurement error were inadequate. With the exclusion of 2 studies examining reliability and responsiveness, no validity studies were found for single items.
Conclusions:
The measurement properties of multiple-item AROMs derived from psychometrics were acceptable (with the exclusion of content validity and measurement error). The single-item AROMs most frequently used in sport science have not been validated. Additionally, nonvalidated modified versions of the originally nonvalidated items are common. Until proper validation studies are completed, all conclusions based on these AROMs are questionable. Established reference methods, such as those of clinimetrics, should be used to develop and assess the validity of AROMs.
Everett, KLA, Chapman, DW, Mitchell, JA, and Ball, N. Effects of westbound trans-meridian travel on countermovement jump performance in international-level rowers. J Strength Cond Res XX(X): 000-000, 2020-International long-haul air travel is a necessity for many athletes as part of their training or competition schedules. However, long-haul travel is also associated with impaired neuromuscular function. An athlete's lower body neuromuscular status is frequently assessed and monitored using countermovement jump (CMJ). This study assessed the impact of westbound trans-meridian travel on changes in CMJ performance in highly trained aerobic athletes. Highly trained male rowers (n = 21, 23.7 ± 1.4 years, 1.91 ± 0.07 m, 86.9 ± 9.9 kg) undertook a westbound flight incurring 22 hours of flight time with 30 hours of total travel time across 9 time zones. Athletes completed a single set of 6 loaded CMJ repetitions before and after travel with performance measured using a digital optical encoder attached to a 20 kg barbell. Each CMJ repetition was assessed for mean concentric velocity, jump height (JH), eccentric displacement, JH:dip ratio, mean power, and mean eccentric velocity, with comparisons made between mean set changes before and after travel. Changes were compared using a one tail paired t-test and characterized using Cohen's d (95% confidence interval) effect sizes. Significance was accepted at p ≤ 0.05. Small-to-moderate changes were observed in all variables following westbound travel. These changes may be because of retention of high training loads before travel resulting in the athletes being in a fatigued state, whereas travel time worked as a forced recovery period. Reductions in CMJ performance are likely following westbound travel, however, may be affected by training fatigue before travel that may confound CMJ performance as a monitoring metric.
Post-lunch sleepiness belongs to biological rhythms. Athletes take a nap to counteract afternoon circadian nadir, in prevision of disturbed sleep. This study examined the effects of brief post-lunch nap on vigilance in young and healthy athletes. The P300 components, physiological and cognitive performances were assessed either after nap or rest, following a night of normal sleep (NSC) or simulated jet lag condition (5-h advance-JLC). P300 wave is the positive deflection at about 300 ms in response to a rare stimulus, representing higher information processing. P300 amplitude reflects the amount of attention allocated whereas P300 latency reflects time spent on stimulus classification. P300 amplitude was significantly increased (Fz:11.14±3.0vs9.05±3.2 µV; p<0.05) and P300 latency was shorter (Pz:327.16±18.0vs344.90±17.0 ms; p<0.01) after nap in NSC. These changes were accompanied by lower subjective sleepiness (19.7±9.6vs27.5±16.5; p<0.05) and decrease in mean reaction times (MRT: divided attention, 645.1±74.2vs698±80.4 ms; p<0.05). In contrast, in JLC, only P300 amplitudes (Fz:10.30±3.1vs7.54±3.3 µV; p<0.01 and Cz: 11.48±3.1vs9.77±3.6 µV; p<0.05) increased but P300 latencies or MRT did not improve. These results indicated improvements in speed of stimulus evaluation time. Napping positively impacts on cognitive processing, especially when subjects are on normal sleep schedules. A nap should be planned for athletes whose performance requires speedy and accurate decisions.
This study determined the effect of long-haul (>5 h) travel on lower body power and match running demands in international rugby sevens players. Lower body power was assessed in twenty-two male international rugby sevens players (age 21.7 ± 2.7 y, mass 89.0 ± 6.7 kg, stature 180.5 ± 6.2 cm; mean ± SD) monitored over 17 rugby sevens tournaments. A countermovement jump was used to monitor lower body power (peak and mean power) over repeated three week travel and competition periods (pre-travel, post-travel, and post-tournament). Small decreases were evident in peak power following both short and long-haul travel (-4.0%, ±3.2%; mean, ±90% confidence limits) with further reductions in peak and mean power post-tournament (-4.5%, ±2.3% and -3.8%, ±1.5%) culminating in a moderate decrease in peak power overall (-7.4%, ±4.0%). A sub-set of 12 players (completing a minimum of 8 tournaments) had the effects of match running demands assessed with lower body power. In this sub-set long-haul travel elicited a large decrease in lower body peak (-9.4%, ±3.5%) and mean power (-5.6%, ±2.9%) over the monitoring period, with a small decrease (-4.3%, ±3.0% and -2.2%, ±1.7%) post-travel and moderate decrease (-5.4%, ±2.5% and -3.5%, ±1.9%) post-tournament respectively. Match running demands were monitored via global positioning system. In long-haul tournaments the 12 players covered ∼13%, ±13% greater total distance (m) and ∼11%, ±10% higher average game meters >5 m·s when compared with short-haul (<5 h) travel. Effective pre- and post-travel player management strategies are indicated to reduce neuromuscular fatigue and running load demands in rugby sevens tournaments following long-haul travel.
Long-distance travel is becoming increasingly common. Whatever the means of transport, any long journey will be associated with "travel fatigue". The symptoms associated with this phenomenon result from a changed routine (particularly sleep lost and meals) and the general disruption caused by travel. Planning any trip well in advance will minimise many of these problems, but some factors are less easy to guard against. These problems include sitting in cramped and uncomfortable conditions and, with flights, the hypoxic environment in the cabin. After arrival at the destination in another country, there can be problems coping with the local language, alterations in food and different customs. If the flight has crossed the equator, then there is likely to be a change in season and natural lighting and, if it has crossed several time zones, there will also be the problem of "jet lag", caused by a transient desynchrony between the "body clock" and the new local time. Moreover, the new environment might differ from the place of departure with regard to ambient temperature and humidity, altitude, natural lighting (including ultraviolet radiation) and pollution. The traveller needs to be aware of these changes before setting off, so that appropriate preparations (clothing, for example) can be made.
A total of 39 subjects were studied after a flight from the UK to either Sydney or Brisbane (10 time-zones to the east). Subjects varied widely in their age, their athletic ability, whether or not they were taking melatonin, and in their objectives when in Australia. For the first 6 days after arrival, subjects scored their jet-lag five times per day and other subjective variables up to five times per day, using visual analogue scales. For jet-lag, the scale was labelled 0 = no jet-lag to 10 = very bad jet-lag; the extremes of the other scales were labelled - 5 and + 5, indicating marked changes compared with normal, and the centrepoint was labelled 0 indicating 'normal'. Mean daily values for jet-lag and fatigue were initially high (+ 3.65 +/- 0.35 and + 1.55 +/- 0.22 on day 1, respectively) and fell progressively on subsequent days, but were still raised significantly (p < 0.05) on day 5 (fatigue) or day 6 (jet-lag). In addition, times of waking were earlier on all days. By contrast, falls in concentration and motivation, and rises in irritability and nocturnal wakings, had recovered by day 4 or earlier, and bowel activity was less frequent, with harder stools, on days 1 and 2 only. Also, on day 1, there was a decrease in the ease of getting to sleep (- 1.33 +/- 0.55), but this changed to an increase from day 2 onwards (for example, + 0.75 +/- 0.25 on day 6). Stepwise regression analysis was used to investigate predictors of jet-lag. The severity of jet-lag at all the times that were measured was strongly predicted by fatigue ratings made at the same time. Its severity at 08:00 h was predicted by an earlier time of waking, by feeling less alert 30 min after waking and, marginally, by the number of waking episodes. Jet-lag at 12:00 and 16:00 h was strongly predicted by a fall of concentration at these times; jet-lag at mealtimes (12:00, 16:00 and 20:00 h) was predicted by the amount of feeling bloated. Such results complicate an exact interpretation that can be placed on an assessment of a global term such as jet-lag, particularly if the assessment is made only once per day.
Sleep hygiene and light exposure can improve performance following long-haul air travel
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Managing travel fatigue and jet lag in athletes: a review and consensus statement
- Janse Van Rensburg
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Injury prevention strategies at the FIFA 2014 world cup: perceptions and practices of the physicians from the 32 participating national teams
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Greater effect of east versus west travel on jet lag, sleep, and team sport performance
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How to manage travel fatigue and jet lag in athletes? A systematic review of interventions
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Do subjective symptoms predict our perception of jet-lag?
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