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Thursday, December 12, 2013
Trinidad & Tobago Guardian Online
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Jetlag in athletes
Many of us have experienced that daytime lethargy and fatigue when we have traveled eastwards to places like London, or the sleepless nights when we have flown westwards to cities like Los Angeles. Yes, jetlag. I have only recently stopped to examine exactly what it is and why it occurs.
Jet lag is a sleep disorder that occurs when one travels across multiple time zones. It manifests as insomnia at night, and/or excessive daytime sleepiness. It is associated with daytime malaise, gastrointestinal disruption, and impaired function in the days immediately following arrival at a destination after transmeridian travel.
It results from the disruption of the circadian rhythms in the body. These are internal cycles, more commonly known as the “body clock,” that last between 20-28 hours. These rhythms influence our sleep-wake cycles, and our core body temperature among other “rhythms.” They are usually synchronized with the earth’s 24-hour light-dark cycle.
Our sleep/wake cycle is primarily influenced by exposure to light and dark cues, with light inhibiting sleep, and dark exposure triggering the release of the chemical melatonin, which encourages sleep. In jet lag, the sleep-wake cycle is out of sync with the local light-dark cycle. This sleep-wake rhythm recovers in about 2-3 days. This is a bit faster than the rhythms of body temperature, which can take over one week to normalize to the local conditions.
As sport has become increasingly international, with athletes traveling across time zones as easily and frequently as if transmeridian travel is a trip down the road, the effects of jet lag have become increasingly important to consider when determining athlete schedules. I was particularly happy to see that the Red Steel team acknowledged these effects when determining the readiness of Sri Lankan Mahela Jayawardene for play in the CPL after his flight from Sri Lanka.
Jet lag can have significant cognitive and physical effects on performance. Disruptions of sleep and circadian rhythms impair cognitive function in athletes, altering mood and causing the deterioration of performance on complex mental tasks. This is detrimental to decision-making in the middle of a match. Some studies showed poorer cognitive performance, lethargy and lack of motivation in the international athletes who experienced jet lag during competitions than those who did not have the condition.
Although there is insufficient research demonstrating the detrimental effects of jet lag on physical performance, direct measures of physical performance such as heart rate, peak muscle force, power output and vertical jump are associated with circadian rhythms. Despite the unavailability of good research, jet lag does appear to have significant negative effects on physical function, a phenomenon to which most of us who have experienced jet lag can attest.
Management of jet lag usually has focused on re-synchronizing the athlete’s sleep patterns to the local time. However, it is also important to take into consideration the longer time the core body temperature cycle takes to adapt. There are also a number of other risk factors that determine who will be affected and for how long. Jet lag will therefore affect some athletes differently than others.
Those with more adaptable sleeping habits will have an easier time acclimating than those with rigid sleep cycles. “Morning people” have less difficulty flying eastward than “night people” who tolerate westward travel better. It is also generally more difficult to travel eastward because this forces the circadian rhythm to shorten in order to adapt to the loss of time caused by the direction of travel across time zones.
Those with higher fitness levels acclimate faster than unfit individuals, so this risk factor should not pose much of a problem for athletes. Also, some studies suggest that local time of destination can play a role in development of jet lag. One study reported that midday arrivals experienced fewer jet lag symptoms than did morning arrivals.
There are a few types of treatment for jet lag. One way of treating is through pharmacological management with drugs such as caffeine and melatonin. The discussion of these is beyond my scope as a physical therapist, and better suited to a physician. Nonpharmacological management includes addressing the modifiable risk factors above, strategic planning of sleep time before and after travel, timing proper meals in the new environment and pre-adaptation to light and dark prior to travel.
Prolonged travel across time zones imparts significant cognitive and physical impairments on the athlete that must be considered in order to avoid performance deficits. Planning for adaptation to the new environment is vital.
Carla Rauseo, DPT, C.S.C.S. is a Doctor of Physical Therapy and Certified Strength and Conditioning Specialist at Total Rehabilitation Centre Limited in El Socorro.
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