Travel Considerations for the Athlete and Sports Medical Team

General Principles

Modern transportation systems facilitate easy access to most regions of the world. Although this has allowed for the rapid growth of international competition, it also creates unique physiologic and psychological challenges for athletes as well as the sports medicine team.

Jet Lag and Chronobiology

  • The American Academy of Sleep Medicine defines jet lag as a syndrome involving insomnia or excessive daytime sleepiness after travel across at least two time zones. Jet lag is a syndrome of symptoms manifested by physiologic adaptations that occur when the body is shifted to a new time zone.

  • Travel fatigue is a more complex combination of physiologic, psychological, and environmental factors that develop during travel; it may accumulate over the course of a season and reduce an athlete’s capacity to recover and perform.

  • Chronobiology is the field that examines cyclic phenomena in living organisms and their adaptation to solar- and lunar-related rhythms; these cycles are known as circadian rhythms.

Physiology of Jet Lag

  • An average human experiences endogenous cycles of energy, mood, and activity that last approximately 25 hours.

  • The primary pacemaker is the suprachiasmatic nuclei of the hypothalamus. When a traveler changes time zones, this pacemaker must undergo entrainment, which is the process of resynchronization with the new environmental light–dark cycle. Physiologic mechanisms involved in this process include:

    • Melatonin, which is a hormone that is typically secreted at dusk by the pineal gland, helps the body anticipate the daily onset of darkness.

    • Adenosine accumulates when a person is awake and causes progressive sleepiness.

      • Adenosine accumulation is blocked by caffeine.

    • Direct neural pathway from the retina

      • Blue wavelength light, in particular, can interfere with the sleep cycle.

    • Arginine vasopressin

  • Zeitgebers are environmental cues that help reset the pacemaker; these include light, temperature, exercise, social interactions, and eating and drinking patterns.

  • Disorders of circadian rhythm are most commonly experienced in the setting of a jet lag when a new sleep–wake cycle is required on entering a new time zone.

    • Signs and symptoms of jet lag include changes in mood, headaches, digestive difficulties, and increased susceptibility to illness. Typically, athletes suffer decreases in cognition, concentration, visual acuity, and memory, which may have adverse effects on physical and athletic performance.

  • The rate of adjustment to a new time zone is typically a day for each time zone crossed.

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