ACSM Personal Trainer Certification Practice Exam

Which metabolic system is primarily engaged during high-intensity exercises lasting 30 seconds to 3 minutes?

1. Oxidation system

2. Aerobic glycolysis

3. Anaerobic glycolysis

4. Protein synthesis

The correct answer is: Anaerobic glycolysis

The primary metabolic system engaged during high-intensity exercises lasting between 30 seconds and 3 minutes is anaerobic glycolysis. This system is responsible for the breakdown of glucose without the need for oxygen to produce energy quickly. During high-intensity efforts, the demand for energy outpaces the oxygen supply available to the muscles. The anaerobic glycolysis system becomes crucial during this time, as it can rapidly generate ATP (adenosine triphosphate) to fuel muscle contractions. The process involves converting glucose into pyruvate, which is then transformed into lactate when oxygen levels are insufficient. This allows for sustained efforts during short-duration, high-intensity activities like sprinting, heavy lifting, or high-intensity interval training. While oxidation, aerobic glycolysis, and protein synthesis are important metabolic processes, they are not the primary pathways utilized in these specific exercise conditions. Oxidation occurs at lower intensities where oxygen is available, aerobic glycolysis operates at a slower pace and longer durations, and protein synthesis is more related to muscle recovery and growth rather than immediate energy production. Thus, anaerobic glycolysis is the key metabolic system supporting high-intensity exercise in this time frame.