A 60-second work interval protocol primarily targets which energy systems?

A 60-second work interval protocol primarily targets which energy systems?

• A. Glycolytic and aerobic
• B. Phosphagen and glycolytic
• C. Phosphagen only
• D. Aerobic only

Answer: (D)

During a 60-second high‑intensity work interval, the body relies mainly on anaerobic pathways to meet the rapid ATP demand. The phosphagen (ATP-PC) system provides immediate energy at the start, but its stores are limited and begin to wane within a few seconds. As those stores deplete, anaerobic glycolysis becomes the primary source of ATP for the majority of the interval. The aerobic system starts contributing as soon as the effort begins and continues to ramp up, helping to support ATP production and lactate clearance, but it cannot supply all the energy quickly enough at that intensity. So the interval is best described as glycolytic-dominant with a notable, but secondary, phosphagen contribution and some aerobic involvement—not aerobic only.

During a 60-second high‑intensity work interval, the body relies mainly on anaerobic pathways to meet the rapid ATP demand. The phosphagen (ATP-PC) system provides immediate energy at the start, but its stores are limited and begin to wane within a few seconds. As those stores deplete, anaerobic glycolysis becomes the primary source of ATP for the majority of the interval. The aerobic system starts contributing as soon as the effort begins and continues to ramp up, helping to support ATP production and lactate clearance, but it cannot supply all the energy quickly enough at that intensity. So the interval is best described as glycolytic-dominant with a notable, but secondary, phosphagen contribution and some aerobic involvement—not aerobic only.