Which energy system is primarily utilized when performing a set of 12 repetitions in weight training?

The anaerobic energy system is primarily utilized during a set of 12 repetitions in weight training. This system is geared towards high-intensity, short-duration activities. When performing resistance exercises like weight training, particularly when the repetitions fall within the moderate to high range (such as 12 reps), the body relies on energy sources that can be quickly accessed to meet the demands of the exercise.

The anaerobic system, particularly the anaerobic glycolysis pathway, does not require oxygen to produce energy. Instead, it breaks down glucose or glycogen to generate ATP (adenosine triphosphate), which is necessary for muscle contractions during the short bursts of effort that occur in weight training. This is crucial because, in a high-repetition set, the demand for energy is immediate, and the body's oxygen supply cannot keep up with the energy needs during such intense activity.

While the other energy systems mentioned play important roles in various types of physical activity, their functions are more suited to different conditions. The aerobic system, for example, is more effective during prolonged, lower-intensity activities, while the ATP/CP system provides energy for very short bursts of maximal effort (like a single lift). The oxidative system is engaged during activities lasting longer than a few minutes