By now, we are all aware of the benefits of fuelling properly when on the bike. When we exercise we use the fat and carbohydrate (glycogen) stored in our body. While even the leanest pro athlete has more than enough fat stores for a training session, we all only have limited glycogen stores. Glycogen is stored in the liver and the muscles as it is transported in the blood as glucose. While we have all probably experienced the dreaded ‘bonk’ when our liver glycogen stores are so low that blood sugar drops; even mild glycogen depletion can lead to a significant reduction in performance.
Sports scientist and coach James Spragg is one of the experts who will be answering your questions in Cycling Weekly's ASK A CYCLING COACH series which comes out every Wednesday. Working both in research and applied settings, he currently runs Intercept Performance Consultancy.
It’s for this reason that whenever I work with an athlete, I will prescribe their training and the fuelling during and after each session. This ensures that the macronutrient intake matches the demands of that particular training session. This approach to cycling nutrition has recently become known as ‘fuelling for the work required’.
The question then becomes – what is really ‘required’ during training sessions?
As a (very) rough guide we can break down sessions in cycling training plans into three categories: Easy rides, long endurance rides, and intensive sessions. Each of these sessions has a different carbohydrate requirement.
What cycling nutrition is required?
These rides are short (<90 mins) and very easy. Typically, so long as you are fuelled before these rides, they don’t require additional carbohydrate intake during the session. However, if you are doing them the day after a race where you might still be a little glycogen depleted it certainly won’t do any harm to take in some carbs.
These Zone 2 endurance rides are longer (>90mins) but still fairly easy (if you are doing them properly). However, due to their duration, you will still be using a significant amount of glycogen during a ride and thus it’s sensible to be taking in some carbs as you ride. At typical endurance intensities, 40-60g of carbs per hour is sufficient.
These can be anywhere from short hard HIIT workouts to long hard races. In those shorter sessions, (<60-90mins) aggressive carbohydrate intake is not recommended as the body won’t be able to process the carbohydrates quickly enough for them to be burned. By the time they have gone through the digestive system, into the blood, and then either to the muscle or the liver, you’ll likely be onto your cool down.
However, in long hard sessions (>90mins) you are going to need to take in a lot of carbohydrates if you don’t want to run out of glycogen and see a drop in your performance.
In this case, you will need to be taking in more than 60g/hr. In fact, some professional athletes are now eating 90-120g/hr of carbohydrates.
Where should these carbs come from?
Now we know how much to eat, the next question is, where should those carbs come from?
Below an intake of 60g/hr I would argue that it doesn’t really matter where your carbs come from. The reason for this is that different types of sugars are absorbed through different channels in the gut. The glucose channel (by far the most common carbohydrate) can get ~60g of glucose out of the gut and into the bloodstream per hour. Indeed, in scientific experiences, at these sorts of intensities, feeding cyclists potato-based pro