Carbohydrates Supplementation

Carbohydrates are crucial for enhancing cycling performance and aiding recovery. In fact, carbohydrates are so important that drinking high-carb mix during a time trial can increase your performance by approximately 3% [1] By understanding the specific details that scientific studies have to offer, you can best equip yourself to avoid bonking, and maximise your chances of going fast.

For general training, it is recommended to consume a mix containing about 0.7 grams of maltodextrin, 0.2 grams of fructose, and 0.2 grams of protein per kilogram of body weight per hour [1]. This is safe and sufficient for most cyclists. However, competitive cyclists aiming for peak performance during prolonged, intense rides may benefit from a higher intake and increased fructose ratio.

Professional cyclists often consume more than 1.1 grams per kilogram per hour. For instance, Harry Sweeny took in roughly 1.9 grams per kilogram per hour during the Milan Sanremo race [2]. To achieve these levels without discomfort, athletes gradually increase their intake, which is referred to as "training your gut."

High carbohydrate consumption is achievable and can be beneficial for long or intense cycling sessions. However, excessive intake can cause gastrointestinal issues, such as gas and diarrhoea, and can even lead to a sudden drop in performance, as was the case with Tadej Pogacar in the Tour de France [3].

The current research suggests avoiding a fructose-heavy carbohydrate mix [1]. High fructose levels can lead to stomach upset, but this can be mitigated by balancing it with maltodextrin in a 1:1 ratio. Furthermore, glucose polymers like maltoxtrin are absorbed faster than fructose, making it more effective for immediate energy needs. In short, don’t have more fructose in your mix than maltodextrin.

Including a small amount of protein in your drink mix can enhance carb absorption. Carbohydrates also play a vital role before and after workouts, mainly to replenish glycogen stores, and the optimal carbohydrate mix for performance during cycling appears to also be the most effective for recovery . As for back-to-back events, muscle glycogen levels equalise after eight hours, whether carbohydrates are consumed immediately or two hours post-exercise. [4]

Adding salt to your mix can help maintain fluid balance, especially if you sweat a lot over a long period of time, but in most cases it has no effect [5]. Mouth rinsing with a carbohydrate solution can activate the brain's reward centres, reducing perceived effort and possibly boosting power output slightly [6].

A potential criticism of a high carb diet is that it reduces fat oxidation in your cells. This has given rise to the “train-low” or “train fasted” methodology, which aims to increase the beneficial adaptations during low-intensity rides by promoting fat oxidation. While it’s true that the more carbohydrates you consume, the less your cells oxidise fat, you should probably not consider any form of low carb diet. As put by the authors of a recent meta-analysis that tested the efficacy of this “train-low” methodology, “In general, LCHF (Low Fat High Carb) diets have been associated with an impaired ability to perform high intensity exercise, a reduced CHO (Carbohydrate) oxidative capacity, a lower energy yield per litre of O2, and reduced mitochondrial respiration, and together this can explain the absent effects of this diet on performance in elite endurance athletes”. Furthermore, the meta-analysis investigated 9 studies and found that completing low-intensity rides fasted had no effect on the training adaptations of trained endurance athletes. [7]

The forest plot of the 9 studies investigated by the authors of the meta-analysis is shown above.

Based on the statistical analysis of the studies, the authors concluded that “overall, the present meta-analysis does not support periodic CHO restriction as a superior approach for enhancing endurance performance in well-trained athletes” [7].

Now that we’ve looked at what science has to say, here is some practical advice. Commercially available gels, chews, and drink mixes provide convenient nutrition but can be expensive. You can purchase maltodextrin and fructose in bulk, which allows you to customise your ratios and is much cheaper. Slight adjustments to the fructose/glucose ratio probably won’t affect your performance, because carb supplementation mainly ensures adequate energy for your muscles and/or triggering your brain's reward centres. Moreover, it doesn’t seem like the type of protein you add to your mix makes a difference.

We recommend that you start at 1.1g/kg/hr as given in the second paragraph, and gradually increase your intake as required. We recommend using a scale to keep your intake precise.

Notes

[1] Unless otherwise cited, the information in this document, including the 3% improvement in time trial value, comes from a meta-analysis in the journal of Sports Medicine. The average time trial or time to exhaustion improvement among the 88 studies that the paper examined was 5%, and after the authors accounted for publication bias, it was lowered to 3%. Time trials included in the meta-analysis ranged from 12 to 120 minute time trials. Generally, carbohydrate supplementation benefitted both short and long time trials, though, in the author's words “the performance benefit was moderately increased for longer exercise durations”.

In the meta-analysis, the authors determined that the effect of gender on the benefit of carb supplementation was unclear.

[2] Harry Sweeny explains his fueling strategy for Milan Sanremo in his Youtube video. He weighs 74 kg according to wikipedia.

[3] Tadej Pogacar speaking about overfueling. We could find no scientific evidence supporting the hypothesis that consuming excessive carbohydrates results in decreased energy availability.

[4] Based on this review in the Current Sports Medicine Reports journal.

[5] Based on the Exercise & Sport Nutrition Review: Research & Recommendations by the international society of sports nutrition.

[6] Based on the meta analysis in the journal of Sports Medicine.

Based on the meta analysis in Journal of the International Society of Sports Nutrition.