Airplane travel effects athletic performance by perturbing the circadian rhythm and inducing a hypoxic effect.
The effects of airplane travel on athletic performance is relevant in a world that is increasingly reliant on flying for athletic competition. Insight from studies that seek to understand and alleviate flying's effect on athletic performance can be translated to enhance a business trip or make a vacation more pleasurable. Athletic performance is an easy assay to measure how well the human body is functioning; most people who step off a plane are not athletes looking to perform at athletic competition. Rather, they want to feel their best as they take on a business conference or a full day of recreational skiing.
A review of airplane travel and athletic performance was recently published in the British Journal of Sports Medicine (Effect of airline travel on performance: a review of the literature, 2013. Leatherwood and Drago).
Airplane travel affects athletic performance in several respects. Changing time zones disrupts our circadian rhythm and reduced oxygen pressure in the cabin produces a hypoxic effect. In addition, sitting in a seat for several hours while on the airplane can produce lethargic limbs.
Circadian rhythm disruption is the foundation of the symptoms of jet lag. The body's master clock, the suprachiasmatic nucleus, resides in the hypothalamus within the brain. The suprachiasmatic nucleus keeps cells in the periphery in sync with the 24 hour day and night cycle. If environmental conditions (changing time zones) force this cycle to change abruptly, cells adapt at different rates. The body functions best once all the cells throughout the body are back in sync. The effect of perturbing the circadian rhythm on athletic performance is evident by a study on Australian National Netball Competition. Travel was categorized by local, north-south, east-west one time zone or east-west two time zones. Teams that crossed one time zone scored less points than those who did not travel across a time zone, but they scored more points than those that crossed two time zones. The figure below illustrates the results from this study.
A study of travel in Major League Baseball competition found that teams had a 61% chance of winning when their opponent crossed 3 time zones. The figure below demonstrates the stark differences in winning percentage based on time zones crossed.
Perhaps the most interesting aspect of the crossing time zone effect on athletic performance is the influence of the direction of travel. Eastward travel is the most detrimental to performance. This is probably because eastward travel results in a shorter day. Without any environmental cues, the human body adapts a 25-26 hour circadian rhythm. The body is better suited for adapting to a longer day, which results from westward travel, then a shorter day, which results from eastward travel. Sleep medication, such as melatonin, can help remedy jet lag because it provides additional stimuli to coax the circadian rhythm to align with the new time zone. Light exposure in the morning or evening can also help the body ease into the new time zone.
Nutrition is another important means of aiding the body to adapt its circadian rhythm. A high carbohydrate, low protein diet induces uptake of tryptophan and subsequent conversion to serotonin, which causes drowsiness. Diets high in fat and calories have been shown to impair circadian rhythm adaptation to the environment in animal subjects.
Airplane travel harms athletic performance via the reduced oxygen pressure. Airplane cabin oxygen pressure is generally maintained at the equivalent of 5,000 to 6,000 feet in elevation. This produces a hypoxic stress. Several hours of flight will cause a drop in arterial oxygen pressure and one may need a day to fully recover their oxygen levels. Studies have shown that athletic performance suffers immediately after returning to altitude.
It may be beneficial to understand the physiological effects of airplane travel, whether traveling for business, pleasure or an athletic competition. The best way to fight the effect of airplane travel is to fly at least a day before competition to provide sufficient rest.