A flight from New York City to Zurich can throw off your body’s internal clock and leave you sleepy and sluggish for days. But before you waste a day of your vacation battling jet lag, scheduled exercise before and during your trip might help you deal and keep your body running like a Swiss watch. Your main circadian “clock” is located in the part of the brain called the hypothalamus. This controls many of your body’s cellular and brain activities, and also determines when you sleep. Your circadian rhythm can be affected by many external cues, such as cycles of night and day, and the availability of food. When you fly a long distance, the external and internal time cues no longer line up, leaving you with the disconnected feeling of jet lag. It turns out that the body’s rhythm also responds to exercise. Researchers tested this on mice, in a new study published in Medicine and Science in Sports and Exercise. They found that scheduled exercise altered the molecular clock in tissues like the muscles and lungs. Other studies have found similar results. People were better able to adapt to eight-hour time shifts—like flying to Switzerland—if they exercised at the same time each day. In both studies, though, exercise had no effect on the brain’s central clock. One role of the hypothalamus is to send out signals to the body with the correct time, similar to how cell towers let your phone know what the local time is when you change time zones. Exercise seems to act directly on the peripheral parts of the body like the muscles, even while the brain is still on New York time. Set your workout routine before your next flight, and stick with it during your trip. It just might keep your body well-adjusted.
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