Managing Travel Fatigue and Jet Lag in Athletes: A Review and Consensus Statement

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 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.

Fig. 1

Schematic diagram of the circadian clock entrainment pathways. Light directly entrains the suprachiasmatic nucleus (SCN), whereas other non-photic zeitgebers exhibit rhythmic changes and entrain the SCN and peripheral clocks throughout 24 h—adapted with permission from Buttgereit et al. [40] and Hood and Amir [41]

Fig. 2

Normal profile of endogenous melatonin (red line) and schematic human phase response curves to light (dark blue line) and exogenous melatonin (light blue line). The y-axis on the right shows the endogenous melatonin concentration. The y-axis on the left shows the direction and relative magnitude of the phase shift following light exposure or exogenous melatonin administration at various times as presented on the x-axis. The magnitude of phase shifts will depend on the dosage used and should not be directly compared—adapted with permission from Eastman and Burgess [5] and Burgess et al. [57]

Fig. 3

A proposed multifactorial model of travel fatigue and jet lag—adapted with permission from Samuels [4]. Travel fatigue (on the left) is influenced by both internal and external factors. Allowing a recovery window taking into account travel distance, travel time, travel frequency and the length of the season combined with monitoring and appropriate management will lead to the ideal outcome. Jet lag (on the right) is also influenced by external factors and less so by internal factors. Travel direction and travel distance, specifically the number of time zones crossed will affect the severity experienced by the individual. Recovery to achieve the ideal outcome relies on resynchronisation of the body clock

Fig. 4

Recommended interventions to help prevent or reduce the effect of jet lag

Fig. 4

Recommended interventions to help prevent or reduce the effect of jet lag

Fig. 5

Combined interventions and short-term travel recommendations to help prevent or reduce the effect of jet lag

Fig. 6

The combined use of light (exposure or avoidance), exogenous melatonin ingestion and administration of short-acting hypnotics to facilitate adaptation to phase shifts from the day of arrival. a Depicts westward travel with the first row illustrating normal home time. The next three rows illustrate travel crossing 4, 8 and 12 h time zones, respectively. Each row represents the current phase of the circadian system on the day of arrival. The CBTmin shifts by 0.5 days per time zone crossed, i.e. delays by 2 h per day and application of interventions need to be adapted according to the shifting of the CBTmin. b Depicts eastward travel with the first row illustrating normal home time. The next three rows illustrate travel crossing 4, 8 and 12 h time zones, respectively. Each row represents the current phase of the circadian system on the day of arrival. The CBTmin shifts by 1 day per time zone crossed, i.e. advances by 1 h per day and application of interventions need to be adapted according to the shifting of the CBTmin. We constructed a recommendation based on a scientific measurement (CBTmin and DLMO) that can be reasonably applied for any number of time zones crossed. Travelling > 8 h EAST, it may be preferable to adapt by delay (moving backward) instead of advance (moving forward) as the body clock adjusts to large delays more easily than to large advances). Once CBTmin at the destination occurs within the scheduled sleep period, partial adaptation is achieved, and the individual is likely to encounter less sleep disruption. Once CBTmin at the destination occurs at the same time as pre-travel (home time), complete adaptation is achieved