Indoor Cycling Fueling: Adjust Your Strategy?

Many cyclists fuel bread and water on the indoor trainer, that is bread and water — no gels, no high-carbohydrate mix, and no added salt. It makes sense because most indoor cycling sessions are under 90 minutes, many of them as short as 30-40 minutes. Why would you need to fuel for such a short duration?

In short: intensity, heat, and sweat.

Nutrition and hydration are two of the most overlooked factors in indoor cycling. Everyone knows about using a fan and smart trainer, but realize the benefits of adjusting your fueling indoors.

Indoor cycling sessions are short and intense. The heat and humidity is significantly higher than most outdoor riding, and you can easily sweat out a few pounds during an indoor trainer session. Should you adjust your fueling strategy for indoor cycling? The answer is a resounding yes — here’s why.

Carbohydrate Intake Has a Huge Impact on Indoor Training

One of the most significant changes to cycling (and all sports) training in the last decade has been revamping our fueling strategies. It was once thought that the upper limit for carbohydrate consumption was 100 grams of carbs per hour, and that was reserved for professionals with trained guts in the Tour de France.

Nowadays, serious athletes are fueling their high intensity training and racing with at least 100 grams of carbs per hour. The evidence, both scientific and anecdotal, has shown that carbohydrate consumption is one of the largest contributors to cycling performance. The more carbohydrates you eat, the better you will perform on the bike (up to a certain limit).

Thanks to advancements in nutritional technology, most cyclists can handle high sugar intake without GI issues. If you had tried to follow this fueling strategy years ago, eating energy bars and thicker sports gels, you would almost always turn your stomach upside down. But now, some cyclists are able to consume upwards of 150 grams of carbs per hour. Some top-level professionals have even been quoted as consuming over 200 grams per hour.

Let’s bring it back to reality… The average cyclist should consume 60-100 grams of carbs per hour during a high intensity workout or race. Beginners should start at 30-60 grams per hour, just to give their gut enough time to adjust to the feeling of processing sugars while riding.

Outdoor riding is generally less intense than indoor riding. Even if you’re doing a hard group ride, you will still spend a significant amount of time coasting downhill or through corners, stopped at traffic lights, or sitting in the draft.

The indoor trainer is a much more intense environment. There is never any coasting (unless you choose to), the draft isn’t quite as strong, and your average power output is almost guaranteed to be higher than riding on the road. Higher intensity means higher fueling demands, and that means increased carbohydrate consumption.

Beginners can start at 30-60 grams of carbs per hour, and then you can progress to 80, 100, and 120+ grams per hour. You don’t need to fuel like this during every workout, only your high-intensity sessions and races.

If your indoor session is 30 minutes or less, you don’t necessarily need to fuel during the ride, unless you are coming into the session fasted (i.e. you haven’t had a meal for more than 4 hours). In that case, consume some carbohydrates at the very beginning of the ride to give you that extra boost to finish the session strong.

How to deal with Heat and Humidity Riding Inside

Indoor training takes place in a hot environment. No matter where you live or where your pain cave is set up, it’s going to be a challenge to cool it down. Personally, I use three industrial-size fans and a portable A/C. Yet, my training space can still sit at 75-78°F during the summer. While that might not seem overly hot, remember that there is zero natural air flow.

Outdoor riding comes with the cooling effect of wind. Even on the hottest days, the slightest breeze can feel oh so good.

Indoor training conditions are hot and humid, which means that we need to adjust our nutrition and hydration. The human body burns more carbohydrates in hot and humid conditions, meaning that you are burning through fuel quickly on the indoor trainer. If you aren’t replacing that fuel, you will inevitably bonk in a pool of sweat.

To take the guesswork out of your training space, you can buy a portable thermometer and humidity gauge for a few dollars. Keep it in your pain cave next to your indoor trainer so that you can monitor temperature changes, and adjust your cooling strategy if need be.

How Much Water Should I Drink on the Trainer?

By now, it should be obvious that you will sweat loads on the indoor trainer. Even with proper cooling equipment, the indoor trainer is a sweat-inducing environment for everyone.

Aim to consume 1-1.5 bottles (18-26 oz) of liquid hydration per hour on the indoor trainer – that means water, sports drinks, and electrolytes. You can aim for the low end of the range when you’re doing a Zone 2 ride, and for the higher end of the range when competing in a race.

The cooler the liquid, the better, because cool liquids can help decrease or maintain your core temperature while riding. Core temperature is a major determinant of athletic performance, and that’s why we’ve seen world champion Tadej Pogačar wearing the CORE temperature sensor.

Studies have shown that increased core temperature is directly related to performance degradation. One study even showed that simply adding a fan to the indoor cycling setup helped double the riders’ endurance during a ramp test.

The same study showed a similar performance boost with precooling effort. That is, lowering the core temperature before the ramp test. Consuming cold liquids is one of the simplest ways to lower your core temperature since you are literally cooling your body from the inside.

Many Hour Record holders and WorldTour riders consume ‘slushies’ on the hottest days. These are near-frozen drinks that are cold in the stomach, perfect for maintaining core temperature during a high-intensity effort.

In the discussion of hydration, we can never forget about electrolytes. It is recommended to use a sweat test kit at home to more precisely measure your sweat rate. These kits can measure the amount of salt and sweat you are losing while riding, and some provide specific hydration recommendations to fit your needs.

You can also do a basic sweat test at home. Hop on the trainer and ride at a medium (Zone 2) pace without any fans or cooling for 20-30 minutes. This will cause you to sweat for an extended period of time. If there is a pool of sweat on the floor at the end of 30 minutes, then you’re probably a heavy sweater.

If you felt hot but didn’t sweat that much, then you’re probably a light sweater. Additionally, check your bibs and jersey for starchy white streaks. These streaks are created by sodium and salt in your sweat. The more salt streaks on your kit, the more electrolytes you need to consume in order to replace them.

If you choose to forgo sweat testing, you can follow this basic blueprint: light sweaters should consume one serving of electrolytes (one salt tablet or sports electrolyte mix) before or during their workout. Heavy sweaters should consume one serving of electrolytes before and two servings during an intense workout or race. Sweat rates are highly individual, so it’s important to experiment with your fueling strategy to see what works best for you.