With the rise of the big-city marathon, more and more runners are traveling to other states and even other countries to race.
Dealing with changing time zones right before a competition used to be a problem only for top athletes, but now runners of all types often want to run marathons in London, Berlin, or Hawaii, making the issue of jet lag and running performance relevant to a huge swath of recreational and age-group runners.
If you’ve read my previous article on the effects of time of day and running performance, you know all about the circadian cycle—the body’s gradual, 24-hour cycle that moderates a large number of biological functions.
Usually, your circadian cycle is in-sync with the regular night-and-day cycles of where you live. The problem with rapid air travel is that crossing a few time zones gets your body’s internal clock out of sync with the external information it’s getting about the time of day.
So, if you are traveling to a race several time zones away, how will that affect your running?
Research on running performance and jet lag
Fortunately, there have been several authoritative reviews over the years that make practical recommendations on how to minimize or avoid the effects of jet lag.
Check this out:
A 1998 review by Roberto Manfreidini and coworkers at the University of Ferrara in Italy claimed that jet lag can cause up to a 10% drop in performance (though no studies were cited for this figure).
Manfreidini et al. cite several studies which appear to show that the direction of travel matters just as much as how many time zones you cross.
When traveling westward, your body seems to be able to adjust its internal clock by about 90 minutes per day, but when you travel eastward, your internal clock is only able to adjust by about 60 minutes per day.
In practical terms, this means that it could take up to five days to fully adjust to London time if you travelled from New York, but the reverse trip would only take three days to readjust to NY time.
Manfreidini et al. also recommend using your meals strategically to re-tune your body’s internal clock.
The researchers suggest that a high-carb, low-protein diet can induce sleepiness, while a high-protein, low-carb meal will increase alertness. This, perhaps in combination with caffeine, can assist your body in recalibrating its sense of morning and evening.
Research on ways to minimize the effects of jet lag
The International Federation of Sports Medicine (FIMS—it’s a French name) has also authored an authoritative review on this topic.
They too chime in on methods to readjust your body’s internal clock, discussing how it not only matters what you eat but when—an 8-12 hour fast, followed by a meal, pushes your body towards assigning “morning” to the break in your fast.
Additionally, FIMS points out that one of the strongest cues to reset your body’ s internal clock is strong, natural light.
Bright lighting in the morning, preferably as strong as possible (direct sunlight is twenty times stronger than your average interior lighting), will help move forward your body’s internal clock, as will exercising in the morning.
On the flip side, bright light or exercise in the evening will turn your body’s clock backwards. So, if you leave JFK Airport at 7am Eastern time and arrive in London at 7pm British time, heading out for a run or turning on all the lights in your hotel room would not be the best way to adjust—your body still thinks it’s around 2pm, and you aren’t providing it the right cues.
Jet lag and the impact on your performance
However, FIMS also points out that adaptability varies among individuals; 30% cross-continental travelers hardly have any trouble adjusting, while another 30% truly struggle.
Interesting:
For unknown reasons, “night owls” seem to adjust better to changes in time zones than “larks,” people who are typically up bright and early.
FIMS cites a more modest performance impairment from jet lag of around 1% for endurance events, though this is still well over a minute over the course of a marathon, and FIMS also predicts that it may take up to five days to fully adjust to a new time zone.
A third review by Drust et al. in 2005 is more suspicious of the effects of jet lag on actual physiology. Pointing out that few field studies have demonstrated a measurable drop in performance due to jet lag (though also noting the extreme difficulty of isolating jet lag from all of the other issues that come along with long-distance air travel),
What’s the bottom line?
Drust et al. instead liken the effect to that of running on no sleep: while actual physiology may not be impaired much, mental functioning and motivation takes a significant hit, making training and competition seem more arduous and less rewarding in the first few days following travel.
Final thoughts
When planning a trip for training or for competition, keep in mind what we’ve learned about your body’s internal clock.
Your body is best primed to perform in the late afternoon and early evening, and worst-prepared in the early hours before dawn.
While there’s nothing you can do about the start time of the New York City Marathon if you’re from the West Coast, you can give your body some cues after you’ve made the trip so it doesn’t feel like you’re starting your race at 6:40am.
- Take in bright sunlight, eat some protein with breakfast (perhaps with some coffee), and get some exercise in the morning to advance your body’s internal clock.
- Wind down your evening with a high-carbohydrate meal and dim lighting to improve your sleep, and if possible, work out your travel schedule so that you arrive a few days early so you can adjust to the time zone, especially if you are traveling to Europe, Hawaii, or another location whose time zone is far different than your own.
While this may not always be possible given scheduling constraints, you can hopefully use some of these tricks to get an edge the next time you toe the line for a big race.
