HIITHigh-Intensity Interval Training

HIIT (High-Intensity Interval Training) alternates brief bouts of near-maximal effort with periods of easier recovery. Sessions are typically short but demanding, in contrast to long steady cardio.

It matters because it's a time-efficient way to improve cardiovascular fitness and VO₂max, and it can burn meaningful calories in little time. But it's taxing to recover from, so more is not better — done too often it interferes with strength training and recovery.

In practice, a couple of well-placed HIIT sessions a week, balanced with easier aerobic work (like Zone 2), gives most of the benefit without digging a recovery hole.