An athlete who is running a 40-yard dash is primarily using which of the following...

The NASM CPT7 Study Guide explains that the ATP-PC system (adenosine triphosphate–phosphocreatine) is the primary energy pathway for very short-duration, high-intensity activities lasting up to about 10 seconds. This system is anaerobic, meaning it does not require oxygen, and it relies on stored ATP and creatine phosphate within the muscles to provide immediate energy. A 40-yard dash is a sprint that typically takes well under 10 seconds for an athlete, placing it squarely in the ATP-PC domain. The guide highlights that this system is ideal for explosive efforts like sprinting, jumping, or heavy lifting due to its rapid ATP replenishment but very limited capacity.