In 2012, Scottish ultra runner and doctor Andrew Murray entered the Gobi Challenge, a six-day race in Mongolia. It did not begin well: ‘A couple of Mongolian runners blasted off on the first day while I struggled with jet lag and a heavy cold,’ he recalls. ‘Sleep is the major determinant of how I’ll perform.’ Jet lag and lack of sleep are becoming increasingly prevalent in our sport. More and more of us fly long distances to take part in races – over 1,500 runners in the 2016 New York City Marathon travelled there from the UK, for example. Clearly you don’t want to put in months of training for a destination race only to have your performance hampered by fatigue or an out-of-kilter body clock. The health and performance effects of long-distance air travel on endurance can be considerable, but there are steps you can take to minimise them.
1/ Lagging behind
A review in Current Sports Medicine Reports, describes jet lag disorder (JLD) as the result of a dissociation between the body’s circadian rhythm and the world’s ‘clock time’ following rapid travel across multiple time zones. Circadian rhythms are the physical, mental and behavioural changes that conform to an approximate 24-hour cycle of light and dark, and explain why we’re alert at certain times of the day and sleepy at others. JLD symptoms include insomnia and poor-quality sleep, daytime sleepiness, impaired alertness and concentration, headache and gastrointestinal issues.
A recent study in the European Journal of Applied Physiology examined 13 physically active males who underwent simulated international air travel. It found ‘that sleep disruption during travel increased perceptual fatigue and reduced lower-body power’.
Dr Kirstie Anderson of the Newcastle Regional Sleep Service is a neurologist and one of the UK’s top sleep experts. She explains: ‘Any journey with less than a two-hour time change probably won’t be troublesome. We adapt to time zone changes at the rate of about an hour a day, so a six-hour change will need at least five to six days for you to be back in sync, which is why elite athletes don’t race soon after long flights. In terms of which travel direction disrupts sleep most, west is best and east is a beast. Jet lag following a westward flight is more easily accommodated because our body clock shifts slowly, and since flying west adds more time to our day we’ve longer to adjust, unlike when we fly east.’
Research backs this up: in a study published in the British Journal of Sports Medicine, 13 athletes flew west across six time zones, and six athletes flew east over eight time zones – it was found that jet lag symptoms persisted one to two days longer for eastbound athletes.
If heading to your destination days before your race is not an option, the most effective way to avoid jet lag is to pre-adapt your circadian rhythm to match that of your new time zone prior to arrival. However, this also may not be practical if your destination’s nighttime is in the middle of your normal day.
At your destination, the goal is to resync your body clock to your destination’s time as quickly as you can. One way is to use a ‘zeitgeber’ – a time cue that tells your body what time it is and helps to synchronise your internal clock.
The best zeitgeber is light, but exercise also works. Japanese research from 2010 found that scheduled exercise helped subjects settle into a new sleep-wake schedule more quickly after an eight-hour time shift – so it’s a good idea to do a morning run at your destination as soon as possible after arrival.
Research from the University of Ferrara in Italy found that the timing and composition of meals can also help speed the resynchronising process. A high-carb, low-protein evening meal – such as pasta – facilitates the brain’s uptake of the amino acid tryptophan and its conversion to serotonin, which helps induce drowsiness and sleep. This also fits in nicely with carb-loading. On the other hand, a high-protein, low-carb meal increases alertness, making an omelette or porridge with yoghurt good breakfast options.
Melatonin, a hormone produced in the brain’s pineal gland, is typically secreted when it gets dark, promoting sleep. It’s found in foods such as oats, sweetcorn, barley, rice, ginger and bananas. In supplement form it is available only on prescription in the UK.
Related: What to eat to help you sleep better
Good sleep hygiene can help reduce jet lag-induced sleep disruption: ensure your hotel room is quiet, around 18C and has blackout curtains or blinds. Aim to go to bed at the same time each night and to sleep for at least seven hours. If you nap during the day, don’t do it later than mid-afternoon, so as to not affect your ability to sleep well in the evening. And avoid caffeine from mid-afternoon onwards.
3/ Homeward bound
For the journey home there is one thing to be aware of – the risk of deep vein thrombosis (DVT). Prolonged air travel can increase the risk of developing a blood clot, typically in the leg. But endurance exercise also affects fibrinolysis – a normal process that prevents blood clots from developing. Normally, the body allows a balance between coagulation (clotting) and fibrinolysis (anti-clotting) to develop, but a study published in the Clinical Journal of Sport Medicine found that prolonged air travel before a marathon disrupted it, and that older athletes tended to be more susceptible. This makes the reduction of DVT risk measures even more important for runners flying long-haul after a marathon: wear loose clothing, consider flight socks, walk around the plane regularly, avoid alcohol and stay hydrated.
Having done all that, rest and recover well – and then get busy planning your next race.
TIPS TO MAKE YOUR LONG FLIGHT MORE BEARABLE
‘Sleep on the plane if it’s bedtime in your destination city,’ says sports physiologist Randy Wilber. If you’re travelling during daytime in your destination country, try to stay awake.
Wear compression socks. The pressure reduces fluid buildup, which helps prevent DVT. The improved circulation can also stave off post-flight leg sluggishness, says Wilber.
Spending hours on a flight is a great way to get sick. Apply antibacterial hand gel liberally. Using a saline nasal spray will help prevent your nose from drying out in the recirculated air.
Dry aeroplane air causes dehydration, which heightens jet lag. ‘It exacerbates the travel-fatigue scenario,’ says Wilber. Aim to drink a cup of water every 60-90 minutes.