What do my muscles use for energy when exercising?
With fitness and nutrition, muscles use primarily fatty acids when exercising. Fatty acids are a breakdown molecule from fat; it also uses glucose which is a breakdown molecule from carbohydrate. In a short term fitness activity where the muscle is only having to work for a short period of time (burst of exercise), the muscle is primarily going to use glucose, or sugar for those activities. As the duration of the fitness activity extends out and you're doing that particular fitness activity for a longer period of time, your muscle will begin to run out of its short-term stores of sugar, and therefore start using the longer sugar molecules as well as fatty acids. This is why people who are interested in losing weight are encouraged to do an aerobic exercise program where they exercise for a longer period of time. This is because their muscles will begin to break down fat components and use fatty acids. The fatty acids have a very high stored energy in it, the muscles will then obtain a lot of energy to continue to contract by burning fatty acids, thus fat is burnt. However, in the short run muscles primarily use sugar; in the long run the muscles use both a form of sugar and fatty acids.
