20-minute HIIT workouts get overpromised. Most programs call something HIIT when it’s really just circuit training at moderate intensity. True HIIT means working at 85-95% of max heart rate during intervals. This protocol — eight rounds of 20 seconds on, 10 seconds off — qualifies. It’s short, brutal, and produces measurable VO2 max improvements.
We put this through its paces in real training sessions and give you the full breakdown — what works, what doesn’t, and whether it’s worth your money.