Backed by extensive research, this classical HIIT workout has produced effective cardio results in diverse populations—from those with pre-existing conditions to elite athletes. Its a challenging workout with four 4-minute intervals at Zone 5 intensity and a total workout duration of 30 minutes.

Here’s how it works:

• Gentle warm up
• 4×4-minute sprints, with a 3-minute recovery between each sprint interval
• Final 3-minute cooldown

Sprints demand maximum intensity, while warm-up, recovery and cooldown are performed at lower intensity.

The workout lasts 30 minutes.