Energy for Muscles

Muscles use ATP from aerobic respiration to contract. However, depending on muscle type (below), anaerobic respiration may be carried out to provide energy very quickly. When this is the case, a reaction involving both ATP and PCr (phosphocreatine) occurs. The trick here is that unlike typical anaerobic respiration, no lactate is produced.

Glycogen stored in muscle is the next port of call for energy during muscle contraction, as it can be broken down into glucose. In the absence of sugar-based energy, cortisol is released which stimulates protein breakdown as another source of energy.

Types of Muscle

There are two main kinds of muscle fibre: slow twitch and fast twitch. Hmm, I do wonder what…