The primary energy source used during short bursts of high-intensity exercise is ATP (adenosine triphosphate), which is stored in the muscles. This source is quickly depleted, typically within 10 seconds of intense effort. Following ATP, the body utilizes creatine phosphate to replenish ATP levels, allowing sustained energy for a few more seconds. After about 30 seconds, the body begins to rely on anaerobic glycolysis, producing lactic acid as a byproduct. Understanding these energy sources helps athletes optimize their training and performance in sports requiring explosive power.