WE’LL DRINK TO THAT
If you think you know all there is to know about hydrating correctly then think again because trail running has its own rules in the drinking game
How, why and when to drink to maximise your running performance
When it comes to taking on fluids there are a number of key differences between running on road and off, some obvious, some less so. Sure the side effects of dehydration – fatigue, cramps, a general lack of enjoyment along the whole route – are pretty much the same whether you’re pounding pavements or tearing along trails. But there are more nuanced, trail-specific factors to take into consideration when deciding how what to drink and how much of it. First off, as a trail runner it’s even more crucial that you monitor your fluid intake and make measuring it part of your running regime. “A body water deficit of 2-3% of your weight is generally defined as dehydration,” says Anita Bean, sport and exercise nutritionist. This can trigger a drop in blood volume and increase in core body temperature puts stress on the heart, lungs and circulatory system, which means the heart has to work harder to pump blood round your body. “The strain on your body’s systems caused by dehydration means that exercise feels much harder, your pace will drop, early fatigue develops, all of which can amount to a drop in endurance performance of 10-20%.”
In extreme cases the runner can collapse, weakened, disorientated and exposed to the element. Trail runners, when training especially, need to drink to suit the conditions.
“Running in the deserts, where temperatures are sometimes up to 50°C you end up drinking much more than a run in the hills of Scotland,” says Trail
Running columnist Dr Andrew Murray, Merrell brand ambassador and consultant in Sports Medicine with the University of Edinburgh. He should know of course. Andrew completed the first run across the mighty Namib desert, which skirts along the Atlantic coasts of Angola, Namibia and South Africa, running 340 miles over nine days in one of the hottest places in the world. He’s also run from Scotland to the Sahara.
“Running about 60km a day through sand dunes I tended to average about 10.5 litres per day so you needed to drink while you ran. If you are on your own, carrying all that water is hard work, but being dehydrated in the middle in the desert is much worse. And drinking your own pee isn’t the solution!”
Trail runners often make the error of not drinking enough on cold days or on runs that will take them into higher, cooler altitudes. There are a number of ways the cold can affect your hydration.
SWEAT LOSS Those additional clothing layers raise the core temperature. The body reacts the only way it knows how, making you sweat more.
We lose the instinct to drink as the body goes into cold mode. Our thirst response can reduce by as much as 40%.
FROZEN OUT In cold, dry conditions air that’s breathed in needs to be warmed and humidified. As that moisture is then lost with every breath out, our body is operating at a deficit.
PEE OFF A side effect of vasoconstriction (the survival mode instinct in which the brain narrows the blood flow canals in our extremities, making the fingertips, toes and nose prone to frostbite) is that our blood pressure will rise. Since the same amount of blood has less space to flow through, the kidneys try to manage this situation by filtering out some of the excess fluid from the blood to reduce its volume. In short, we pee more. Think drink “Dehydration can result in a drop in stamina and running pace,” says Anita. “In one study running speeds over 5km and 10km dropped by 6-7% in runners
who were dehydrated (2% body weight loss) compared with full hydration. But dehydration also leads to mental fatigue, a drop in concentration and low mood,” adds Anita. This is especially crucial for fell and trail runners.
Consider jockeys for a moment. Pro racing jockeys were among a group of exercisers tested to measure the cognitive impact of not drinking enough fluids during intense exercise. Even at relatively low levels of dehydration – 2% body weight loss – the professional riders were found to struggle when tested to measure their speed of reaction and judgement. These guys have to make quick calls when travelling over unstable terrain in race conditions, taking evasive action to avoid injury… Sound familiar?
“Elite runners may tolerate slightly higher levels of dehydration than nonelite, perhaps as high as 3-4% body weight loss, before experiencing negative effects on their performance,” says Anita.
“On a race day or long run I drink SiS gels every 6km – non-caffeine ones for the first half of the race, caffeinated for second,” says Dr Andrew Murray. The caffeine will help you focus on those trip hazards as our body starts to tire.
Weights and measures
The biggest trade off for trail runners when it comes to maintaining proper hydration surrounds the need to carry water – increasing your load in the process. Run duration, conditions, weather and your own training levels all need to be factored in when ensuring that you’ve got enough fluid to keep you performing to the best of your ability.
Current advice is to drink to thirst not ahead of thirst. “Generally, 400–800ml per hour when running will prevent dehydration as well as over-hydration,” suggests Anita. “It’s better to drink little and often, say 100-150 ml every 15 minutes, as this results in greater retention and less urination. If you’re running for less than 60-90min, drink water when you feel thirsty,” she says.
If you’re running at a moderate or high intensity for more than 60-90min, then you may benefit from carbohydrate in your drink. Diluted squash (1:6 dilution), an isotonic sports drink or coconut water all provide hydration as well as an optimal concentration of carbohydrate. For Dr Andrew Murray a few hydration hard truths have helped him:
The things that hydrate you most are rehydration salts/tablets (SiS and HealthSpan Elite have great products), and skimmed milk.
Drink enough so that pee is clear or straw-coloured, and then only have a sip or two in the hour prior to a race. Try and force a pee out just before racing!
For a marathon, I’ll take small sips often, and try and make sure I’m eating something with carbohydrates in it every 6km, starting at 6km.
You’ll no doubt find your own formula to stay hydrated. We’ll drink to that!