Metabolism for Endurance Athletes, Part 2

A week or two ago, I published Metabolism for Endurance Athletes, Part 1, which I recommend you read if you haven’t. Biology was not something of interest to many of us in high school, but knowledge of human metabolism is very helpful in planning and executing endurance training. Last time, the main topic was an overview of the three types of molecules which fuel us, as well as a broad overview of how this knowledge can help an athlete perform better. Here, I want to cover the reason why it’s important to stay hydrated in order to perform aerobic exercise.

Identifying and improving limiting factors is the name of the game with endurance training.Broadly, endurance exercise performance comes down to aerobic metabolism. Sugars and fats are converted into energy with the oxidizing assistance of Oxygen, acquired from breathing, producing carbon dioxide and water. There are many points of interest in this little story for an endurance athlete, and I hope to explain a few in coming posts. But for today, what would you guess is the limiting factor in the chain?

Think of the body in terms of a car engine. The sugars and fats are like gasoline. The fuel is converted to useful energy by combining with oxygen, and burning, producing carbon dioxide and water. There is ample energy available in the gas tank; you can run an engine for hours on a tank of fuel. Similarly, there are days of fuel (mainly stored as fat) in our bodies except in cases of extreme starvation. The limiting factor, both in bodies and car engines, is Oxygen.

Oxygen molecules have a bit of a journey to go on in order assist with metabolism. Once air is inhaled into the lungs, it must diffuse into the blood, onto hemoglobin molecules, and then move physically to the muscle. This journey takes time, and there are only so many molecules of hemoglobin in the blood to facilitate this journey. Oxygen transportation is not only limited by how many hemoglobin molecules are in the blood, but also how quickly the body can circulate that blood.

Some of the main adaptations that come from endurance training are improving the capability of the heart to move blood through the body. Thinner fluids flow easier than thick ones. Staying hydrated, therefor, is a key way to maintain your aerobic performance, particularly in the heat. Studies have shown that when a person loses body weight in water equivalent to 3% of their body mass, their VO2 (a measure of maximal consumption of Oxygen) is decreased by 5%. Keep this in mind the next time you’re preparing for a workout on a hot day; hydration is key to performance, keeping your blood thin helps your heart move oxygen to your muscles, and makes performance possible.

If you’re looking to start training for a goal, or want to take your performance up a level, get in touch with me at brycoward@gmail.com.