Make Your Cardio Work for You

Day 4
Outdoor intervals (All workout times include 5 minutes of warm-up and 5 minutes of cool-down.)

Beginner
Work: 30 seconds at 70% MHR
Active rest: 2 minutes at 35% MHR
Intervals: 4
Advanced: 20 minutes

Intermediate
Work: 1 minute at 80% MHR
Active rest: 4 minutes at 40% MHR
Intervals: 4
Total time: 30 minutes

Advanced
Work: 1 minute at 85% MHR
Active rest: 4 minutes at 45% MHR
Intervals: 6
Total time: 40 minutes