How do I hydrate for a marathon MTB race?

It’s one of the questions we’re asked most often here at MarathonMTB.com, so we chatted to our team of marathon riders and put together a bunch of answers, starting with the most pressing one… What to drink?

What should I drink in a marathon MTB race?

It really boils down to a couple of choices (yes, that’s a pun): water, and electrolyte mix. Within the electrolyte mix category, there are as many different preparations as there are products, so it’s important to know exactly what to look for.

But back to water versus electrolyte. Water is nice. It’s good for your teeth, it’s cheap, and it’s really what we’re trying to replace. But for a marathon mountain biking event (that’s an event that’s typically going to take you over four hours to complete), it’s rarely going to do the trick because you’re losing more than water in your sweat, and your carbohydrate needs are through the roof.

You could opt to drink water, and add in gels and some salt tablets, but, as team rider Mike Blewitt points out, you’re making your work harder:

‘During an XCM race, I try to take in at least 60g of carbohydrate an hour. That’s about three of the SIS gels that I use, or one-and-a-half Cliff bars,’ says Mike. ‘It sounds easy enough, but that’s 12 gels, or 6 cliff-bars, and I can barely fit that in my pockets alongside all my spares, let alone eat it with anything like good timing. Marathons are more and more technical, so riders often struggle to take a hand off the bars to chow down. Loading my bidon or Camelbak with electrolyte/carb mix is just the most practical way to get more nutrients in. I’ll still be eating solids, but not as much as I’d otherwise have to.’

There are only a few situations in life when an artificial, sugary, salty drink is better for you than water. During prolonged, intense exercise like a marathon MTB race, there’s nothing better.

What’s all the fuss about electrolytes?

Electrolytes are basically minerals that your body loses during sweat, usually as salts, and can’t make on its own. The most important of these is, of course, sodium. We lose between 600 to 1500mg of sodium per litre of sweat, and endurance athletes can sweat out anything between two and four litres an hour. Drinking too much without adequate sodium can lead to a dangerous condition called hyponatraemia, and while a lot of sports drinks come nowhere near covering sodium lost in sweat, they replenish enough to keep you out of harm’s way. Sodium plays a role all the way down to your nutrition intake. Get the sodium right, and you’ll hydrate better. The better hydrated you are, the better food is absorbed and the less likely you are to experience stomach upsets during a gruelling marathon race. In short, never skip the sodium, especially if it’s hot.

Ok, so I’m drinking sports drink. Um. Which one?

Products like Nuun or Hydralyte, those mixes that come in tablet form, have little or no carbohydrate. They’re great for rehydration, and excellent during hot training rides when eating’s not a problem. During an XCM, however, we recommend you get a proper electrolyte/carb mix.

On the other hand, not all energy drink mixes actually contain electrolytes (like the all-important sodium), and you definitely need those, so be sure to check the nutrition information.

Some research shows that combining different kinds of carbohydrates—glucose and fructose—which are absorbed differently, can maximise your uptake of carb, and we’ve had good results trialling products that combine both, so there’s another feature to look out for.

How strong should I mix my electrolyte/carb drink?

A general rule of thumb is to mix it slightly stronger than directed in cold conditions (because you’ll lose less fluid through sweat, but you still need that carb) and slightly weaker in hot conditions (because you’ll want a bigger fluid:carb ratio to help with hydration). Recent thinking also suggests that four per cent carb content, or hypotonic drink mix, is most effective. While your typical pre-mix sports drinks like Gatorade provide about six per cent carb, there’s a lot of evidence that, in hot weather at least, about a four per cent mix is better absorbed. That’s about 180 calories per litre from carbohydrate.

How much should I actually drink?

Like everything to do with nutrition, it depends! We all have vastly different sweat rates, and weather conditions, genetics, body size, and exercise intensity all influence our fluid requirements. The only way to tell is to do a little experiment. The AIS suggest you weigh yourself before a training ride, then after, making a note of how much you drink. Subtract your finishing weight and fluid intake from your initial weight and you have a general idea of your fluid loss. Repeat this on a cool day and a warm day for a bit more intel.

Camelbak or bidons?

You’ll nearly always see your XCM heroes racing with bidons—but is that the best strategy for you? Bottles do have advantages. They’re easy to swap over, it’s easy to measure and see how much you’ve drunk and have left to drink,and they keep the extra weight down low and centred on your bike. On the other hand, the pros have support crews who meet them at several points during a race, so there’s no fear of going without. For the rest of us racing self-supported, bottles can be a hassle. You’ll have to stop to fill up a few times during an event, so you’ll have less control of what goes in—all that careful thought about sodium and glucose/fructose ratios and hypotonic mixes goes out the window when a feed zone only has water, bouillon, or coke on offer.

The Subaru-MarathonMTB.com team have been experimenting with Camelbaks more and more. Rider Imogen Smith explains: ‘I do a lot of racing in very hot conditions. I only have room for one bidon cage on my Norco Revolver 29 FS, and 700ml often won’t get me from one feed zone to the next’.

‘I find I hydrate better using a Camelbak—and there are a lot of reasons. I don’t have to stop every 20-kilometres to search for my bottle among hundreds of others, or refill with some unknown pre-mixed stuff. In XCM racing you often don’t know what’s coming up on the trail, so it’s nice not to be caught with a bidon in one hand when you hit a rock garden or something. With a Camelbak I can keep both hands on the bars most of the time,’ she says.

‘I typically have two and swap over at one of the feed zones or transitions in the race—I did this in the Flight Centre Epic National XCM recently and it was great. I pull the empty one off while I’m still moving, so it’s a very quick change. I fill my Camelbaks with sports drink, and give them a good wash after every time I use them. Camelbaks are incredibly underrated and one of the most useful race-tools I have in the garage,’ says Imogen.

Is there anything else I need to know about hydration?

• Drink better, and with the right amount of sodium, and you’ll find you have a better stomach throughout the race.
• The temperature of your drink can affect its absorption. If your drink gets hot, it’s slower to absorb and you could get that sloshy stomach feeling. Refrigerate your bidons or fill an Esky with ice before an event. Our riders use insulated bottles like Camelbak’s Podium Big Chill in really, really hot events to help with this, and to help keep their core temperature down.
• Coke, cordial, or juice aren’t great substitutes for a proper sports drink. They’re about 10 per cent carbohydrate and have very little sodium. A bit of Coke might give you a boost, but drink a lot of these sugary solutions and you’ll find your ability to stay hydrated and consume sufficient quantities of both fluid and carb is compromised.
• Don’t wait to feel thirsty. Drink to a schedule—a few gulps every 10–15 minutes in cool weather, and more if it’s hot. Every time you hit a smooth piece of trail or road, take advantage of it so you’re hydrated for the stretches of technical riding that follow.
• A couple of sports drink products that tick all our boxes are Scratch Labs Hydration Drink Mix (designed according to some of the most up-to-date thinking on hydration), or Torq Energy mix (a pleasant tasting all-rounder). Neither product is a sponsor, we’ve just found them great through our own research, and trial and error.