The energy system used to perform one set of 15 repetitions of a barbell bench press:

The anaerobic lactic system is the primary energy source utilized when performing a set of 15 repetitions of any strength training exercise, such as the barbell bench press. This energy system is activated when an activity requires more energy than can be supplied by the aerobic system and occurs in a time frame of approximately 30 seconds to 2 minutes, which aligns well with the length of a set containing multiple repetitions.

When engaging in moderate to high-intensity exercises that involve repeated movements, the body relies on the anaerobic lactic system to break down glucose for energy without utilizing oxygen, producing lactic acid as a byproduct. Since 15 repetitions typically exceed the very short burst of energy duration provided by the ATP-CP system, which primarily fuels activities lasting up to about 10 seconds, the anaerobic lactic system becomes the predominant energy system during this type of workout.

In contrast, the aerobic system is mainly activated during prolonged, less intense activities, where oxygen is utilized for energy production over longer durations rather than brief high-intensity efforts like a set of bench presses. The heart, lungs, and circulatory system play essential roles in transportation and delivery of oxygen throughout the body, but they do not constitute an energy system by themselves; instead