Which structure is described for a 20-minute HIIT session?

• A. 4-6 cycles of 30 seconds high-intensity work with 60 seconds rest.
• B. A 20-minute continuous run at a steady but high effort.
• C. A 1:2 work-rest ratio depending on goals.
• D. 6 cycles of 1-minute sprints with 2 minutes rest.

Answer: (C)

The main idea here is that HIIT structure is built from how long you work and how long you recover, and for a set 20-minute session you tailor that ratio to your goals and fitness level. A 1:2 work-to-rest ratio provides a flexible framework: your recovery is twice as long as your work, which helps you sustain effort across multiple intervals while staying within the total time. You can adjust either the work duration or the rest duration within that ratio to match what you’re aiming for—more endurance-focused work might use shorter work bouts with proportionally longer rests, while aiming for power could shift the lengths while keeping the ratio.

For example, using 30 seconds of work and 60 seconds of rest yields a cycle about 90 seconds long, so you can fit roughly 13 cycles in a 20-minute session, allowing a brief warm-up and cool-down. Other options describe fixed patterns that don’t emphasize adjusting the work-rest relationship to fit the total time and goals, which is why the flexible 1:2 ratio is the best description here.