Hydration is king indoors
Hydration is important with any type of cycling. The biggest difference indoors is that you simply sweat more. When you go hard at room temperature and little airflow, your body will run hotter and produce more sweat in order to try and cool down. With fluid loss caused by sweating, your blood becomes more viscous and your heart has to work harder to distribute it to your muscles. This leads to a heart rate increase also called a cardiac drift. So, when you notice that your heart rate is higher than usual, it’s the first warning sign of poor fluid management. Even relatively small dehydration around 2% can be detrimental to your performance. Hydrating well is a key part of your indoor nutrition.
Determine your sweat rate
The general recommendations to drink somewhere between 500-1,000 ml of fluids per hour of exercise are a good starting point. But if you really want to know how much you personally should drink on race day, it is worth trying to measure your sweat rate. You can do this at home, it’s not something exclusive to professional cyclists. All you have to do is weigh yourself naked and dry before a training session and then after it. The difference in kilograms will tell you how many litters of fluids you lost.
As a rule of thumb, drink 1,5 litres of fluid per 1 kilogram of body weight lost after the training session. Distribute this amount of liquid throughout the day. Just note that this sweat rate applies to indoor training only.
Make sure that what you’re using to hydrate during exercise contains some electrolytes, at least a good amount of sodium. This is to compensate for the electrolytes lost through sweat. Some carbohydrates can also help with hydration and as a source of energy too. You should test in training whether you should go with hypotonic or isotonic drinks.
Pre-race nutrition is actually quite similar whether you’re about to ride outdoors or indoors. Around 2-3 hours before the race is when you should have your last full meal. This meal should contain some protein and complex carbohydrates and shouldn’t be too heavy on fats and fibre as that could slow down digestion. Around 60 minutes before the race, you can add a light snack made up of easily digestible carbohydrates. This could be a banana or an energy bar.
The duration of indoor races is another big difference you have to take into account. Outdoor training sessions and races are commonly longer than 2 hours. This, typically, calls for 60-90 g of carbohydrates per hour to be able to maintain optimal performance. However, most indoor sessions on Zwift only last between 30 and 60 minutes. This means you can rely much more on glycogen – your body’s stored carbohydrates. It’s still a good idea to get some external carbs but you need much fewer in this short time.
The best way to get some carbs in is via electrolyte drinks or energy gels. Solid food is not really an option, it wouldn’t be digested well at such high intensity. For shorter races, a gel 10-15 minutes before your start will be sufficient. For races lasting 60 minutes or more, try to hit the 60 g of carbs per hour with a combination of gels and drinks. This usually means an additional gel every 30 minutes.
We can’t forget about caffeine. It’s been proven to reduce perceived effort and allow you to push harder. That’s crucial in short indoor races. The important thing about caffeine is that it takes a while to fully come into effect. An effective strategy for caffeine ingestion is to have 3 mg per 1 kg of body weight (or about 1 espresso) about 60 minutes before the start of the race.
How do pros fuel virtual rides?
These are the basics of hydration and fuelling for indoor training and racing. But everyone approaches it differently. After all, it’s still a relatively new arena for cyclists to compete in. Here are a few insights from our interviews of pro riders.
Advice from Andy Schleck, 2010 Tour de France winner
“A long indoor training session for me as a professional was 2 hours. Sometimes, I would do 2 hours in the morning and 2 hours in the afternoon but never more than 2 hours in one session. And the average indoor workout for most people will usually be around 1 hour. I believe that if you have a healthy lifestyle and you eat properly throughout the day, you don’t need to eat during that 1-hour session. But if you do a monster session of 4-5 hours at home, then you do need to eat something,” Andy says.
“You should have a lot of water or some isotonic drink at hand’s reach because you do sweat a lot, more than when you ride outside. That way you don’t have to stop your training in the middle. A fan can create the feeling you sweat less because it feels cooler but the temperature in your room is still the same even with a fan. So, be careful to stay hydrated while you do the workout,” warns Andy.
Advice from Luke Roberts, sports director of Team Sunweb
“We would basically treat indoor races the same as a 1-hour time-trial. The riders would have their final meal about 3 hours before the race and then just a light snack 1-1,5 hours before. During the race itself, it’s not possible to be taking in solid foods with such an intense short effort,” said Luke Roberts. They would stick to sports drinks with electrolytes and gels for energy and hydration on the bike during the race, very much like with any time trial lasting over 30 minutes.
Whether you’re just starting with Zwift or trying to break into the professional scene, make sure to always practise your hydration and nutrition in training. You have to figure out what your digestion can handle. You don’t want any surprises on race day!