Goal: Develop the explosive, alactic energy system
How: Start in the middle of your blue zone, then go at 100% intensity for 5-10 seconds. Lower your heart rate back down to the middle of your blue zone over a 40-60 second rest period. If you need to rest longer to achieve 100% intensity in the next round, extend the rest period. Repeat for 10-20 reps.
Exercises: Choose a low-impact exercise, such as biking, rowing, etc.