How Honey At Breakfast Can Give Cyclists Extra Watts

As we covered in a previous blog post on breakfast (See here), consuming a high carbohydrate meal in the 3 hours pre-ride has a modest impact on our muscle glycogen, only increasing stores by around 10%. So when maximising our muscle glycogen stores ahead of long hard rides, we need to allow up to 24-36 hours and sufficient carbohydrate intake to achieve this. 

One limitation of the study was that it only directly measured muscle glycogen, though. Whilst they mentioned that there was a good chance that some of the carbohydrates in the breakfast meal would have gone to liver glycogen storage, we don’t know if that happened, and they also didn’t assess the impact of the breakfast on performance. 

In sports nutrition, there is growing interest in the liver as it’s a vital source of carbohydrates for the muscles later in exercise, as our muscle glycogen stores become depleted. Our liver maintains our blood glucose, and fatigue during prolonged riding often corresponds with a drop in our blood sugar to low levels (called hypoglycaemia) which typically occurs when our liver glycogen stores run low. During the early parts of exercise, we typically rely heavily on our muscle glycogen stores, but as these become depleted, we shift to using more liver glycogen. 

During an overnight fast (i.e. when we’re not eating as we’re sleeping), our muscle glycogen stores do not typically change. However, our liver provides glucose to fuel organs such as the brain whilst we sleep, which means that liver glycogen can drop by as much as 25% overnight. So, strategies to enhance glycogen storage in the liver at breakfast to recover this drop can potentially benefit performance.

In 2022, Dr Tim Podlogar of the University Of Birmingham/Bora Hansgrohe Pro Cycling Team and colleagues set out to look at the impact of consuming different types of carbohydrates on subsequent cycling capacity (i.e. how long someone can ride before they become fatigued). See the study here. 

In particular, they were interested in the impact of including fructose at breakfast on cycling capacity. Fructose is a fruit sugar found in high amounts in foods such as honey, dried fruit, fruit juices, agave nectar and sweets. Fructose is unique because the liver preferentially metabolises it and has to be converted into glucose before it can be stored as muscle glycogen. This makes it a great source of carbohydrates when trying to maximise liver glycogen storage. 

The study took a group of well-trained cyclists and, on two occasions, gave them two different breakfasts, both containing 2 grams of carbohydrate per kilogram body weight; the breakfast was either fructose powder with rice or glucose powder with rice. 2 hours after consuming the meal they then rode on a bike at a fixed pace (just below their ventilator threshold) for as long as they could. 

Despite both trials consuming exactly the same amount of carbohydrates at breakfast, the glucose and rice trials were only able to complete around 130 minutes of cycling before fatiguing on average. In contrast, the fructose and rice trial participants managed to complete 137 minutes of cycling on average, which corresponded to a significant increase in exercise capacity.

Whilst the study didn’t directly measure the impact of the different carbohydrates on glycogen stores (measuring liver glycogen requires an MRi Scanner, a radiographer and a physicist, which not many sports science labs have access to), theoretically, the difference in performance could be explained by the potential improvement in liver glycogen storage that would likely have occurred in the fructose trial. Interestingly, previous research has also shown that substituting some glucose for fructose post-exercise didn’t negatively impact muscle glycogen storage but did increase liver glycogen storage.

 So, what does this mean as an athlete? 

When it comes to breakfast before a demanding training session/competition, including some fructose-based carbohydrates, is likely to enhance liver glycogen stores significantly and give you more fuel towards the end of the exercise, improving your exercise capacity and delaying the point at which you become fatigued. 

Therefore, selecting high fructose foods as part of your pre-ride meal is an easy way to help enhance your performance using food. High fructose foods include things like honey, maple syrup, agave nectar, dried fruits such as raisins and apricots and fruits such as mangos and grapes, apples and pears, either in whole form, as juices or fruit purees. 

Coach Ben