Why Breakfast Alone Isn't Enough To Fuel Up Before A Big Ride

When it comes to a big ride (i.e. anything over a couple of hours in duration, predominately to moderate to high exercise intensities), to ensure we can perform for the duration of the ride, we need to ensure we have sufficient carbohydrates available for the demands of the ride. This means that before starting the ride, we need to ensure you have sufficient glycogen (the name for carbohydrates stored in the muscles and liver) stored. 

When our limited glycogen stores get low, it generally corresponds with fatigue, and the amount of glycogen we have when we start to exercise is closely associated with the amount of exercise capacity we have (i.e. how long we can ride hard for, before we become fatigued). 

Many riders see the pre-ride meal as critical for fuelling up, but how much glycogen can you actually store in the few hours immediately before a big ride?

A study from the University of Loughborough back in 2004 looked to measure precisely this. They took a group of recreationally active male endurance runners and brought them into the lab after an overnight fast. At 08:00, they took a sample of their muscle to measure their muscle glycogen levels before giving them a breakfast. 

The breakfast was a textbook example of what a sports nutritionist would typically recommend an athlete consume before a demanding training session or competition. It contained 2.5 grams of carbohydrates per kilogram of the participant’s body weight, so for a 70-kg athlete, this would be equivalent to around 175 grams of carbohydrates. So, it was a relatively large meal, but certainly not ridiculous. 

The meal selected was relatively light, had a low fat, fibre and protein content and contained fast-digesting sources of carbohydrates. The meal consisted of (for a 70kg athlete at least) 105grams of white bread – equivalent to around 3 slices, 70grams of jam, 56grams of cornflakes with 280ml of skimmed milk and 147ml of orange squash made with 315ml of water to wash it all down. They were given 15 minutes to consume the meal. 

 Three hours after eating the meal, another muscle sample was taken to analyse how much glycogen had been stored in the 3 hours since eating it. This is where things got interesting. 

The average results of the 8 participants showed that muscle glycogen stores had only increased by just over 10%. Interestingly, when we look at the data for each individual participant, one individual increased their glycogen by 31%, and another only increased it by 5%, potentially due to having different amounts of glycogen before starting feeding. So, whilst the athletes had consumed a lot of carbohydrates, it had had quite a modest impact on their glycogen stores. 

Interestingly, 67% of the ingested carbohydrates were not accounted for. The study didn’t measure liver glycogen stores (the other major store of glycogen alongside muscle), so there is a good chance that some of the ingested carbohydrates went to this. Around 10% of the carbohydrate was also used as energy in the 3-hour period. This suggested that much of the carbohydrate was still potentially in the stomach awaiting digestion at the 3-hour mark. 

What does this mean? We’ll effectively if you want to ensure you have sufficient glycogen available for a hard ride, you can’t simply rely on the meal immediately pre-exercise to boost your glycogen stores sufficiently. In fact, based on typical data, we need at least 24 hours to get our glycogen stores from moderate to supercompensated levels. With the caveat that this only happens when we combine adequate rest with sufficient carbohydrate intake. 

Our glycogen stores are a little bit like our mobile phone batteries. We can’t just plug in your phone for 5 minutes and expect the battery to charge fully. It takes time, and the battery charge rate depends on the battery level. As athletes, we see the fastest rates of glycogen storage in the period immediately post-exercise, where our glycogen stores are at their lowest. In the same way, we see our phones charge fastest from low battery levels. As battery/glycogen levels fill up, the storage rate becomes slower, and it, therefore, takes more time to store glycogen. 

To summarise. If you are doing a hard, demanding ride, then start thinking about increasing your carbohydrate intake as much as 24-36hours prior to turning the pedals, as relying on breakfast alone to maximise your glycogen stores isn’t going to be sufficient when performance is your focus, and you're riding hard for more than a couple of hours. 

Focusing more on fuelling the day before also means you can have a lighter meal before exercise, which is less likely to cause you stomach issues whilst on the bike. 

-       Coach Ben