How long does jetlag affect physical performance?
Athletes have to fly to competitions — it’s an inevitable part of international sport. But flying long distances can hurt performance. There are lots of “rules of thumb” that people use to plan travel and competition (e.g. allow one day of recovery for each time zone crossed), but not a lot of hard evidence. Australian researchers have just published a neat study in the European Journal of Applied Physiology that sheds a little light on this question.
The study looked at five members of the Australian skeleton team before and after a flight to a training camp in Canada that took 24 hours and involved four different flights (so a pretty brutal travel schedule, but not that rare for athletes). Two days before they left, they did a bunch of power tests: box drop jumps, squat jumps, and countermovement jumps. Once they arrived in Canada, they repeated these measurements daily for 11 days. Some Canadian skeleton athletes (who didn’t have to fly) also did some of the tests as a control.
The data, frankly, is pretty messy. Performance clearly drops after the flight, but the various measurements aren’t perfectly consistent about when the biggest drops come and how quickly performance returns. Here’s a bit of sample data, showing the squat jump height. The two squares (instead of circles) are the Canadian controls — they basically just show that there’s not much day-to-day variation in the measurements for non-jetlagged athletes:
So what’s going on? The researchers believe that it’s not just being cooped up in a plane for a day that causes the problems:
We would contend that a symptom of jet lag is circadian misalignment and as such the performance declines that we are reporting are the result of circadian misalignment due to trans-meridian flight.
Seems fairly reasonable. The solution:
This research highlights that where possible, athletes performing explosive short duration efforts as part of a competitive environment should time their arrival in the destination country following long haul travel at least five days prior to the competition.
This I’m a little more skeptical about. Looking at the data, it’s hard to see any particular break point after five days. That being said, in the balance between leaving too little time to recover versus arriving too early and being out of your element for too long, five days does seem like pretty good common sense.