Make Your Cardio Work for You

Day 2
Indoor intervals (All workout times include 5 minutes of warm-up and 5 minutes of cool-down.)

Beginner:
Work: 30 seconds at 75% MHR
Active rest: 1:30 minutes at 40% MHR
Intervals: 4
Total time: 18 minutes

Intermediate
Work: 1 minute at 80% MHR
Active rest: 3 minutes at 50% MHR
Intervals: 4
Total time: 26 minutes

Advanced
Work: 2 minutes at 85% MHR
Active rest: 6 minutes at 60% MHR
Intervals: 4
Total time:42 minutes