What is the primary energy source for sprinting during the first few seconds?

Sprinting during the first few seconds primarily relies on creatine phosphate as the energy source. When a sprint begins, the body quickly needs energy to fuel high-intensity muscle contractions. Creatine phosphate, stored in the muscles, is utilized to regenerate adenosine triphosphate (ATP), which is the immediate energy currency of the cell. This process occurs rapidly and does not require oxygen, allowing for quick bursts of energy necessary for activities like sprinting.

In the initial phase of sprinting, the anaerobic energy system, specifically the phosphagen system, dominates. This system can provide enough ATP for nearly 10 seconds of maximal effort, which aligns with the duration of the energy demand in a short sprint. After this initial phase, the body starts to rely on glycogen stores and other energy systems for sustained activity, but at the very start, creatine phosphate is the key contributor.