Endurance exercise relies on carbohydrates, fats, and proteins as fuel sources, with carbohydrates being the fastest burning fuel used during high-intensity exercise.
Ingesting carbohydrates during endurance exercise can help maintain energy levels and prevent hitting the wall, with the recommended amount varying based on duration and intensity of the activity.
Combining glucose with fructose can increase carbohydrate absorption and utilization to optimize fueling during endurance exercise, while finding the right source and concentration of carbohydrates is important to avoid gastrointestinal issues.
Deep dives
Understanding Fuel Sources in Endurance Exercise
In endurance exercise, the body relies on three main fuel sources: carbohydrates, fats, and proteins. Carbohydrates are the fastest burning fuel and are used when exercise intensity is high. Fats are the slowest burning fuel and are utilized during low-intensity exercise. Proteins can also be used as fuel, but only in extreme energy deficit situations. The crossover concept explains how the contribution of carbohydrates and fats to energy production shifts as exercise intensity increases. Training can increase an individual's ability to burn fat as fuel, making them more efficient endurance athletes. Hitting the wall, or running out of energy, occurs when carbohydrate stores, such as muscle glycogen, become depleted. Ingesting carbohydrates during exercise can help maintain energy levels and prevent hitting the wall.
Carbohydrate Intake for Endurance Exercise
The amount of carbohydrates needed during endurance exercise depends on the duration and intensity of the activity. For exercise lasting less than 45 minutes, no additional fueling is necessary. For exercise lasting 45 minutes to 2 hours, consuming 30 to 60 grams of carbohydrates per hour is recommended. For longer durations, it is recommended to consume as much carbohydrates as tolerable, possibly exceeding 60 grams per hour. Increasing carbohydrate intake during exercise can improve performance and reduce fatigue. Practical sources of carbohydrates during exercise can include energy drinks, gels, and sports drinks.
Factors Affecting Carbohydrate Consumption
The rate of carbohydrate consumption is limited by the body's ability to absorb carbohydrates from the gut. The sodium glucose transporter in the gut determines the maximum rate at which carbohydrates can be absorbed. By combining glucose with fructose, the body can increase carbohydrate absorption and utilize more than 60 grams per hour. High concentrations of carbohydrates can cause gastrointestinal issues, so finding the right source and concentration of carbohydrates is important. Experimenting with different products and training the gut to tolerate higher carbohydrate intake can optimize fueling during endurance exercise.
Practical Considerations for Carbohydrate Consumption
Consuming carbohydrates during endurance exercise can help maintain energy levels and delay fatigue. Sports drinks, gels, jellies, and other products containing a mix of glucose and fructose are commonly used for fueling. Finding the right concentration and amount of carbohydrates that work for each individual is essential. It is important to consider the duration and intensity of the exercise, as well as one's own tolerance for carbohydrate intake. Building up tolerance through training and gradually increasing carbohydrate consumption can optimize performance and prevent hitting the wall.
Importance of Carbohydrate Ingestion for Athletes
Carbohydrate ingestion during training and competition is crucial for athletes to enhance performance. Athletes are now consuming around a hundred grams of carbs per hour during races to optimize their performance. It has been recognized that running out of carbs is detrimental, and delivering more carbs to the muscles during exercise is beneficial. Studies have shown that increasing carbohydrate intake during training can result in better performance and reduced fatigue. The recommended approach is to consume 60 grams of glucose per hour along with fructose for a combined effect.
Timing of Carb Consumption for Optimal Performance
The timing of carb consumption plays a significant role in performance, especially during pre-race meals. Consuming carbs within two to three hours before exercise helps to fill up the glycogen stores and ensures an adequate supply of glucose for the start of exercise. However, consuming carbs too close to exercise can lead to reactive hyperglycemia, where blood glucose levels rise and then fall rapidly, negatively impacting performance. Athletes need to be mindful of timing their meals to avoid this post-meal drop in blood glucose levels. During exercise, the glycemic index (GI) becomes less relevant, as the goal is rapid disposal and oxidation of carbohydrates.
Prof. Ross Tucker and sports journalist Mike Finch break down the various forms of energy the body uses, how they work, how we fuel them and when to use what. Plus learn to decipher the ingredients in energy supplements, understand why carbs are still king and how best to train your body to become an efficient endurance machine. A must-listen for any endurance athlete. Get bonus content on Patreon