What is the dominant fuel system around 90 seconds into a confrontation when Lactic Acid System is depleted?

The dominant fuel system around 90 seconds into a confrontation, particularly after the Lactic Acid System has been depleted, is indeed the Aerobic System. Once the high-intensity efforts of the initial phases have transitioned from the anaerobic pathways and the lactic acid buildup has reached its limit, the body shifts to utilizing oxygen to generate energy.

In this aerobic phase, the body efficiently burns calories from carbohydrates and fats to support prolonged physical activity. This transition allows for sustained energy production, essential during extended confrontations or physical efforts. The aerobic system becomes crucial for maintaining performance and endurance when glycogen stores begin to lower after initial bursts of energy that rely heavily on the anaerobic systems.

The other fuel systems mentioned, while important in different contexts, do not dominate at this particular timeframe following intensive effort. The ATP/PC System is primarily utilized for short bursts of energy (around 0-10 seconds), the Muscle Glycogen System pertains to stored energy in muscles but becomes less effective as fatigue sets in and is more associated with the anaerobic phase, and the Fat Oxidation System, while important for longer-duration activities, operates at a lower intensity and is not as immediately effective in high-stress confrontation scenarios.