The famous carbohydrate question (again!)

Anyone who is even remotely interested in sports nutrition knows that it can be confusing to understand what to put into our bodies to always perform at our best. Unfortunately, there is no magic formula, as many factors come into play: our metabolism, how regularly and intensely we train, our lifestyle (sleep, stress management, social life), etc.

Still, it's legitimate to want to know how to eat in order to become a better version of ourselves. Fortunately, if there is one thing that is well established in the field of sports and widely supported by the American Society of Sports Medicine (ASSM), it is that consuming carbohydrates before, during, and after exercise maximizes performance, meets energy needs, promotes muscle contraction, and aids recovery.

In fact, at moderate intensity (aerobic), muscles use just over 50% of energy in the form of glycogen; this proportion can increase to 90% when we feel like sprinting... To illustrate this concept, let's say that our bodies run on glucose to move forward and store this "fuel" in the form of glycogen in the liver and muscles.

Is it possible to adapt your metabolism?

If our bodies can become more efficient with each pedal stroke, could our metabolism also be trained to use energy substrates more efficiently? In recent years, various theories of metabolic adaptation have attempted to answer this question. They all revolve around the "train low, compete high" model. This model, which comes in several variations, aims to adjust the amount of carbohydrates consumed before and/or after exercise. To do this, you can train with few carbohydrates, train twice in the same day, or train intensely in the evening and the next morning on an empty stomach (sleep-low).

The goal? To metabolically adapt our muscles to be as efficient as possible while using less fuel. A bit like a hybrid car model that uses less gas to get to the same place as quickly as a traditional car. Among other things, these adaptations would improve certain muscle metabolic characteristics associated with oxidative capacity, enzyme activity, and increased use of lipids as an energy source (lipolysis). 

Although these practices appear to alter metabolic activity during exercise, they do not always translate into improved performance. In fact, among recent interventions using this model, only 37% of studies observed significant improvements in performance. In addition, athletes must follow this type of protocol for at least 3 weeks to see any significant metabolic changes[2].

A new player: the glycogen threshold

In a real-world setting, far removed from the controlled environment of a laboratory, it is difficult for an athlete to strictly follow such a restrictive and psychologically demanding protocol. And you won't be surprised to learn that restricting carbohydrates before and during exercise leads to a gloomy mood and a significant decrease in the will to push oneself. Since the mind has a significant impact on our perception of fatigue and our ability to maintain pace, this factor should not be taken lightly.

Faced with this problematic phenomenon, some researchers have come up with a new model, known as "fuel for the work required," which is an amalgamation of theories derived from "train low, compete high."[3] This theory of carbohydrate periodization takes into account not only the intensity and duration of training sessions during the week, but also the glycogen threshold (glycogen threshold). It refers to the principle that there is a window where the available glycogen is sufficient to meet the energy demand generated by physical effort, but Socks trigger metabolic changes. According to these researchers, the way to achieve this is to adapt our daily carbohydrate requirements per meal according to the intensity, duration, and objectives of the planned training sessions (aerobic, anaerobic lactic, or alactic).

In other words, this method would allow our bodies to learn how to use glycogen intelligently depending on the energy system being used, while always having enough fuel to provide the necessary intensity and thus perform well.

An intervention study tested this on 11 male amateur athletes. Initially, each athlete had to consume a large amount of carbohydrates around their workouts, then reduce their intake in an attempt to enter the "glycogen threshold" zone. The two interventions were separated by a period of 7 to 9 days. Basically, the results of this study show that pre-workout carbohydrate restriction can lead to interesting metabolic changes, such as the use of lipids as fuel, compared to a high-carbohydrate protocol. In addition, the researchers found that it is imperative for athletes to consume a good amount of protein WITH carbohydrates after exercise in order to recover adequately from a muscular standpoint.

But, but, but!

Let's keep in mind that these different techniques should be viewed with caution, as it cannot be said that they always contribute to improving performance. It would seem that simply following a specific diet, counting macronutrients, or experimenting with "train low, compete high"theories could lead to slight weight loss, which in itself can lead to noticeable improvements on the bike. However, it should be noted that these physiological and even weight changes are mainly seen in seasoned athletes who train regularly.

Nevertheless, periodizing carbohydrates on a daily basis could lead to greater metabolic flexibility and help athletes maintain their pace, regardless of the type of training. Workouts that require alactic energy systems in intervals would therefore benefit from adequate carbohydrate intake. Conversely, carbohydrate restriction would be more beneficial during tempo zone workouts, below the lactate threshold.

Although all this sounds promising and intriguing, it is important to bear in mind that these techniques are primarily intended for high-level athletes seeking to perfect the art of pedaling more efficiently. They require commitment on the part of the athlete, who must carefully calculate their intake and, above all, understand the dynamics of energy pathways during training.

For ordinary people like us, the important thing is first and foremost to enjoy the world of cycling and to have enough energy to push our limits, gain confidence, and above all, want to do it again the next day. To achieve this, the recipe remains the same: enjoy a variety of foods without restriction, in a balanced way, and above all, with pleasure!

For those of you who are more fitness-oriented, here is an example of periodization tailored to the effort required for a 70 kg man. 

* Taken from Impey, S.G. et al., 2018

References 

1. Cochran, A.J., et al., "Carbohydrate feeding during recovery alters the skeletal muscle metabolic response to repeated sessions of high-intensity interval exercise in humans, " Journal of Applied Physiology, 2010.

2. Gejl, K.D., et al., "No superior adaptations to carbohydrate periodization in elite endurance athletes," Medicine & Science in Sports & Exercise, 2017.

3. Impey, S.G., et al., "Fuel for the work required: a theoretical framework for carbohydrate periodization and the glycogen threshold hypothesis," Sports Medicine, 2018.

4. Impey, S.G. et al., "Fuel for the work required: a practical approach to amalgamating train-low paradigms for endurance athletes," Physiological Reports, 2016.