Lesson 1 - Fueling Your Stroke, Buying and Burning Gas

Six 200’s descending on five minutes. Twenty-five 50’s on :58. Whatever your “favorite,” every set during every workout and dryland session requires energy.

Nutrients are the “chemicals” that supply the body with energy. Carbohydrate, protein and fat supply energy in the form of calories. These are your “Energy-Yielding Nutrients.” Vitamins, Minerals and Water don’t supply energy in the form of calories, but their presence is required in order for the body to access the energy provided by carbohydrate, protein and fat.

During exercise, the body gets its energy primarily from carbohydrate and fat. It likes to save protein for other things (building and repairing muscle tissue, hormones and red blood cells, and supporting the immune system). The only time the body uses protein as an energy source during exercise is when carbohydrate and fat are not present in sufficient quantities. This happens when the total caloric intake is too low over a period of months, and or the bout of exercise is so long that the body’s accessible sources of carbohydrate and protein become exhausted. Neither of these scenarios is desirable for swimmers.

Think about money. When you have lots of it, you don’t mind paying full price for things. But when money is scarce, or there is just too much you have to buy, you look for bargains. You’re not being cheap, just thrifty. Simplified to some extent, your body knows how to shop.

Now instead of dollars, think of your currency as oxygen. When swimming is “easy,” say during warm-up or your easiest sets, there is plenty of oxygen available to support the exercise. The body perceives itself as “rich” and doesn’t mind splurging on fat (1 gram of fat costs 9 oxygens). In fact, it automatically does so because it knows it might need carbohydrate at a later time.

When exercise is hard (we’re talking tough sets, definitely your hardest sets), oxygen is not plentiful. In fact, the body needs every bit it can get to support the exercise, but even that is often not enough, and the body is forced to derive energy in ways that do not require oxygen (i.e. anaerobic metabolism). In this situation, the body perceives itself as very “poor” and becomes very thrifty with its “purchase” if fuel. Since carbohydrate costs less than fat (1 gram of carbohydrate costs 4 oxygens), the body chooses to rely primarily on carbohydrate for its energy.

Keep in mind that this entire fuel burning process is never a case of “all or none.” In other words, the body is always using some combination of carbohydrate and fat, but the intensity of the exercise dictates which fuel source will be the dominant one. When swimmering is easiest, fat is the primary fuel source. When swimming is toughest, carbohydrate is the primary fuel source. When swimming is about 50% of maximum effort, carbohydrate and fat contribute about equally.

Let’s face it – the majority of workouts are hard. Above 50% for certain. If you consider the typical swim workout, it’s pretty safe to say that the primary fuel source for swimmers IS carbohydrate.