The Basal Metabolic Rate (BMR) is the minimum amount of energy we require to stay alive, and is measured by monitoring oxygen and CO2 excretion.
ATP - Adenosine Triphosphate
ATP = ADP + P + Energy (ADP - Adenosine Diphospate)
Muscles store enough ATP for a 2 second contraction - this would supply sufficient energy for muscle contractions of short duration such as required for weight lifting, power lifting and shot putting.
Energy is released when a phosphate is broken off the ATP returning it to ADP. The cycle is continous, with ADP being converted back to ATP.
ATP breaks down to release energy when a nerve impulse stimulates a muscle fibre. The energy used from the breakdown of food joins a phosphate ion to ADP via a high energy bond.
The Energy Systems
There are three energy systems in the body that produce ATP. These are:
Factors Contributing to Muscle Fatigue