Which energy system is primarily engaged during the first 10 seconds of high-intensity exercise?

The ATP-PC system, also known as the phosphagen system, is primarily engaged during the initial 10 seconds of high-intensity exercise. This energy system provides immediate energy through the breakdown of adenosine triphosphate (ATP) and phosphocreatine (PC) stored in the muscles.

During short bursts of intense activity, such as sprinting or weightlifting, the body relies on this anaerobic system because it can supply energy rapidly without the need for oxygen. The ATP-PC system is capable of fueling maximal efforts for a brief duration, typically up to 10 seconds, before the stored ATP and phosphocreatine are depleted. Following this time frame, the body starts to utilize the lactic acid system, which relies on glycolysis to produce energy, but it is the ATP-PC system that dominates in the very first moments of high-intensity efforts.

As a result, this system is crucial for performance in activities that demand rapid and powerful movements, making it fundamental for athletes engaging in sports that require quick bursts of energy.