Which energy system primarily fuels a 90-second maximal effort?

• A. Phosphagen (ATP-PC) system
• B. Glycolytic (lactic acid) system
• C. Aerobic system
• D. Fat oxidation

Answer: (B)

At this duration, the body relies mainly on anaerobic glycolysis. The phosphagen (ATP-PC) system is the fastest source but is exhausted within roughly the first 10 seconds, so it can’t sustain a 90-second maximal effort. The aerobic system can eventually provide energy, but its rate is slower and it doesn’t peak as the primary source at this intensity and time frame. Fat oxidation is too slow and inefficient to support maximal effort at this duration. Therefore, anaerobic glycolysis is the best fit to supply ATP quickly to sustain a near-maximal effort for about 90 seconds.