The initial energy release in the cell comes from the cleavage of ATP to ADP.
However, the intracellular pool of ATP is small and during intensive exercise, the ATP is used in approximately 3 seconds. Following this, it is regenerated by creatine phosphate in the reaction outlined below:
The creatine pool in the body allows for a further burst of energy of approximately 6 seconds before that too is depleted and requires regeneration.
Low levels of creatine in muscle can lead to rapid fatigue and underperformance in short-burst, intensive exercise. Creatine supplementation can ensure muscle saturation of creatine and produces significant improvement in short-burst energy level and athletic performance.