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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.
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Vol.:(0123456789)
Sports Medicine (2021) 51:2029–2050
https://doi.org/10.1007/s40279-021-01502-0
CONSENSUS STATEMENT
Managing Travel Fatigue andJet Lag inAthletes: AReview
andConsensus Statement
DinaC.JansevanRensburg1,2 · AudreyJansenvanRensburg1 · PeterM.Fowler3 · AmyM.Bender4 ·
DavidStevens5,6 · KieranO.Sullivan7,8 · HughH.K.Fullagar9 · Juan‑ManuelAlonso10 · MichelleBiggins7 ·
AmandaClaassen‑Smithers11 · RobCollins12,13· MichikoDohi14· MatthewW.Driller15 · IanC.Dunican16 ·
LukeGupta17· ShonaL.Halson18 · MicheleLastella19 · KathleenH.Miles20 · MathieuNedelec21 ·
TonyPage22· GregRoach19· CharliSargent19 · MeetaSingh23 · GraceE.Vincent19 · JacopoA.Vitale24 ·
TanitaBotha25
Accepted: 7 June 2021 / Published online: 14 July 2021
© The Author(s), under exclusive licence to Springer Nature Switzerland AG 2021
Abstract
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 perfor-
mance 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 circa-
dian 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 con-
sensus 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.
* Dina C. Janse van Rensburg
christa.jansevanrensburg@up.ac.za
Extended author information available on the last page of the article
1 Introduction
The modern-day athlete is often required to travel domes-
tically and internationally including high-frequency short
distances (< 3h) and low-frequency long distances (> 3h)
that may involve the crossing of numerous time zones. The
subsequent travel fatigue and jet lag experienced result in
a myriad of shared symptoms, such as daytime fatigue,
decreased concentration and alertness, sleep disruption
and gastrointestinal disturbances [1, 2]. These can lead to
increased illness and injury risk as well as adverse effects
on athletic performance [29].
Travel fatigue and jet lag are two distinct entities that
may co-occur when travelling east or west across three or
more time zones [2, 4, 1012]. Travel fatigue occurs in all
travelling athletes and can be acute following any individual
long journey, or chronic (cumulative) as a consequence of
repetitive travel within a season [4, 10]. It is a multi-domain
disturbance that generally occurs with any travel regard-
less of the direction of travel or the number of time-zones
crossed [2, 4, 10, 13]. It is caused by the demands of travel
itself, such as cramped conditions, prolonged mild hypoxia,
changes in the external environment (trans-latitudinal travel
i.e. winter–summer/summer–winter) and reduced physical
activity [10]. Jet lag is episodic with similar but more severe
and prolonged symptoms compared to travel fatigue and fol-
lows rapid travel across 3 or more time-zones (transmerid-
ian travel i.e. east–west/west–east) [4, 10]. It is typically
characterised by the desynchronisation between the internal
human circadian system and the time at the new destination
[2, 4, 10, 11, 14]. As a result, the circadian rhythm of sev-
eral psychological, physiological and behavioural variables
with a typical early morning nadir and late-afternoon peak is
misaligned with the new local time. Depending on the train-
ing or competition time, this could directly affect athletic
performance [2, 4, 5].
Although the circadian system is well understood and
described in the circadian physiology literature [5, 1519],
it remains difficult to translate and to apply this knowledge
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... Sleep is one of the most essential factors for human health, and the lack of sleep can cause a large amount of diseases [1]. Jet lag is quite different from the travel fatigue [2,3]. Paragliola, R. M. et al have shown that travelers who cross over 6 time zones will suffer much more serious jet lag than short-distance travelers [3]. ...
... But considering the symptoms show no relationship between cortisol level and subjective feeling, the author supposes that there should be another theory which can explain what causes the difference between symptoms. Janse van Rensburg, D. C. et al paid attention on athletes who may cross time zones frequently in 2021 [2]. According to the researchers, athletes from the National Hockey League (NHL) and Major League Baseball (MLB) travel more than 40,000 km every year, which means that athletes are excellent targets for the study of the affection of jet lag. ...
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... The magnitude of the change in drowsiness levels between before and after the flight, as predicted by the SAFE model, was similarly found to be slightly greater when traveling east than west (Fig. 5). This is consistent with numerous studies showing that the human body is less adapted to flying across time zones to the east than to the west [35,36]. For example, it has been reported that sleep after flying eastward across time zones is more erratic and fragmented than after flying westward [44]. ...
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The sentiments and feelings like the aforementioned may clearly affect the balance between happiness and wellness (Calleja-Gonzalez et al., 2018). In that way, coaches focus on respecting, valuing, involving, engaging in dialogue with, listening to, and supporting players, as well as treating them as human beings, giving them the confidence and feelings of responsibility to try (BarkerRuchti et al., 2014). There is a clear need for more research in this area, although some advances were already made by examining empathy using qualitative methods and identifying factors of empathy between athletes and coaches (David and Larson, 2018). Furthermore, a period of constructive reflection considering the relationship between performance analysis and recovery is strongly recommended (Calleja-González et al., 2018). Thus, there is a gap between research and reality (Buchheit, 2017), because players express that they are more fatigued from traveling than from training or competition, which is the focus of this letter.A shift in the approach to sports performance research seems to be necessary. For example, sleep quality and quantity (Gupta et al., 2017), burden associated to traveling (Fowler et al., 2014), chronobiological disturbance (Drust et al., 2005) are often cited as limiting factors of performance in high level sport, and their impact should be considered and assessed. Further, the additive effect or the means by which one factor influence another should be taken into account (Tobias et al., 2013).Elite athletes are exposed to substantial training loads , however, that is only a (small) part of the key determinants of performance. Current trends in expertise describe the concept as a dynamically varying relationship captured by the constraints of the environment and those of the performer of a task (RW.ERROR -Unable to find reference:4304). Using this approach, the context is key and should not be detached from the content, thus, the guidelines for designing and implementation of a training program will benefit from incorporating environmental information, integrated periodization, mental performance, skill acquisition, or nutrition (Mujika et al., 2018). In addition, using the aforementioned methods in combination with athlete monitoring of training, competition and psychological load, and pooled with assessments of recovery, well-being, and illness . It may enable the achievement of enhanced performance levels.Since extended traveling is common in elite sport (Flatt et al., 2019), it is recommended that coaches and applied sports scientists consider the following key points in order to minimize injury risk, enhance recovery, optimize performance and bring down the effect of traveling and sleep disturbance on performance (Vitale et al., 2019):-Monitor external training load (before, during and after competition) using tracking systems (Fox et al., 2017) with the least possible invasion.-Monitor Internal responses using heart rate measures and biomarkers in blood, saliva and/or urine before, during and after competition (Halson, 2014).-Monitor daily sleep quality, sleep duration, and player wellbeing to inform same day adjustments to training and competition workload (Fox et al., 2019).-Arrive early to competition destination in order to include sufficient time on-site to recover from traveling and adjust to new time-zones, altitudes, climates and environments (Lastella et al., 2019).-Avoid environmental changes because changing physical sleep environments may increase susceptibility to altered sleep responses, which may negatively affect performance (Pitchford et al., 2017).-Develop and apply consistent strategies (pre, during and post-traveling) that may help prevent or ease jet lag (Fowler et al., 2014).-Develop and apply an ad-hoc nutrition plan for traveling .Stress on the body is probably cumulative (Issurin, 2009). Therefore, the development of new variables, such as ratios, that might relate player's fatigue, training demands, match performance, environmental conditions, at home or away, could be an interesting open window to explore. Further, the creation and validation of a travel fatigue scale would enhance an understanding of the travelling effect. Also, a scale of mental fatigue (Russell et al., 2019) that informs about the stress derived from training, competition and environmental stress would be most useful.With the increasing popularity of sport, number of contests, and travel demands on the rise, the importance of athlete load monitoring in combination with nutritional programming, implementation of recovery methods, and proper sleep practices cannot be underestimated. Taking these steps will make for a more effective travel experience and support athlete health and playing career longevity. In the same page, rationalizing the use of measurement instruments and procedures seems also a need, as anecdotally suggests that "strict data-led regimes undermine trust and stifle creativity, shackling a player's natural empathy with the game", thus, "it is vital that those who oversee performance in elite sport consider the consequences on players of such intense surveillance". • Bus/plane traveling (seats ergonomic, number of disposable seats in bus/plane).• Seating positions/dangerous seating positions (players education and control).• Muscle activation during traveling.• Intellectual activity during traveling.• Problem with sleep medicaments (hypotonic effects).• Sleep banking between travels and games.• Designing individual players traveling profile.• Plane/bus vibration effect on athlete's bodies.• Plane/bus engine noise stressor effect.
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To accommodate daily recurring environmental changes, animals show cyclic variations in behaviour and physiology, which include prominent behavioural states such as sleep–wake cycles but also a host of less conspicuous oscillations in neurological, metabolic, endocrine, cardiovascular and immune functions. Circadian rhythmicity is created endogenously by genetically encoded molecular clocks, whose components cooperate to generate cyclic changes in their own abundance and activity, with a periodicity of about a day. Throughout the body, such molecular clocks convey temporal control to the function of organs and tissues by regulating pertinent downstream programmes. Synchrony between the different circadian oscillators and resonance with the solar day is largely enabled by a neural pacemaker, which is directly responsive to certain environmental cues and able to transmit internal time-of-day representations to the entire body. In this Review, we discuss aspects of the circadian clock in Drosophila melanogaster and mammals, including the components of these molecular oscillators, the function and mechanisms of action of central and peripheral clocks, their synchronization and their relevance to human health. Animal circadian rhythms are controlled by central and peripheral molecular clocks, whose components generate oscillations in their own abundance and activity. Insights into how these clocks time the function of organs and tissues is increasing our understanding of animal physiology.
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Caffeine is considered a cognitive enhancer at low to moderate doses because it improves alertness, vigilance, attention, and reaction time. However, no previous investigation has assessed the effect of acute caffeine intake on e-sports-specific performance. The aim of this investigation was to determine the effect of the ingestion of 3 mg per kg of body mass on simple reaction time in a color test and on hit accuracy and reaction time during a first-person shooting game. Fifteen professional e-gamers (age= 22 ± 3 years) participated in a double-blind, cross-over, randomized experimental trial. In two trials 3 days apart, participants either ingested a placebo (cellulose) or 3 mg/kg of caffeine in an opaque and unidentifiable capsule. After a 45-min wait for substance absorption, participants performed 5 attempts at a simple reaction time test and completed a first-person shooting game that included 3 attempts at a 2-min game with 60 fixed targets (180 targets in total). Reaction times (in both tests) and accuracy in hitting the targets (only in the shooting game) were measured. In comparison to the placebo, caffeine decreased simple reaction time (0.20 ± 0.01 vs. 0.19 ± 0.01 s, P < 0.01), the mean time taken to hit the targets (0.92 ± 0.07 vs. 0.88 ± 0.07 s, P < 0.01) and enhanced hit accuracy (98.8 ± 0.92 vs. 99.8 ± 0.35% of targets hit, P < 0.01). In summary, the acute ingestion of 3 mg/kg of caffeine reduced the time taken to react to a simple stimulus, decreased the time taken to hit a fixed target and improved accuracy in hitting the target in a first-person shooting game in professional e-gamers. Thus, the caffeine ingestion (3 mg/kg) might be considered as an ergogenic aid for e-sports gamers based on its effect to enhance hit accuracy and time.
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Objective measures of circadian disruption are difficult to capture in a free-living environment hence the importance of validating subjective measures of jetlag. We aimed to assess the internal consistency of the 15-item Liverpool Jetlag Scale and its convergent and divergent validity with indicators of fatigue and anxiety in a large sample of air passengers. Online survey of passengers was conducted after travel on a range of long-haul flights. Jetlag was captured using the Liverpool scale, fatigue was measured using the Vitality subscale of the Short-Form Health Survey (SF-36), and the presence of anxiety or worry before, during, and after flight was self-reported. Inter-item correlations and Cronbach’s alpha were calculated to assess the internal consistency of the scale. Exploratory factor analysis was used to examine whether the scale was consistent with one underlying construct of circadian disruption. Correlations between fatigue and anxiety (flying, situational, symptoms) with jetlag were used to assess convergent and divergent validity. Linear regression was used to determine the most important symptoms contributing to subjective jetlag rating. N = 460 passengers (57% female, mean age 50, SD 16 years) were surveyed. Cronbach’s alpha indicated high internal reliability (alpha = 0.85). Jetlag was more strongly correlated with fatigue (rho = 0.47) than any type of anxiety (rho = 0.10–0.22). Exploratory factor analysis indicated responses were consistent with four factors: (i) fatigue/daytime impairment, (ii) sleep disturbance, (iii) changes in appetite and (iv) changes in bowel function. Regression analysis indicated that only changes in concentration, sleep time, fatigue, sleep quality and frequency of bowel motions were independent correlates of subjective jetlag (R² = 27%). The Liverpool Jetlag Scale is internally consistent and demonstrates the expected relationships with fatigue and anxiety. Patterns of response are not consistent with all items being derived from one underlying factor, i.e. circadian disruption. Further, not all items contributed to the jetlag rating, suggesting the single-item rating may be useful for capturing the subjective experience of jetlag, whilst a total jetlag score is useful for also capturing circadian symptoms considered by passengers to be unrelated to jetlag. Validation of subjective jetlag against objective measures of circadian disruption is required.