The 3 x 20 protocol is an example of which type of CR fitness interval training?

• A. High Intensity Interval Training (HIIT)
• B. Sprint Interval Training (SIT)
• C. High Intensity Functional Training (HIFT)
• D. 4 x 4 protocol

Answer: (B)

Short, all-out efforts with brief, near-full recoveries define Sprint Interval Training. The 3 x 20 protocol fits this pattern: three 20-second maximal sprints with enough rest to recover between each push. This structure aims to tax the anaerobic energy systems quickly and repeatedly, boosting sprint speed and anaerobic capacity.

If we contrast with the other options, you can see why this fits SIT best. High-intensity interval training often uses longer work bouts at high but not necessarily maximal effort, with varied rest and more flexible pacing. Four-minute work intervals, as in a 4 x 4 protocol, create a different endurance stimulus and are not the very short, all-out sprints that define SIT. High Intensity Functional Training is a broader method emphasizing functional moves and varied circuits rather than a defined short-sprint interval pattern. So the specific three 20-second, maximal-effort sprints with recovery align most closely with Sprint Interval Training.