Red Threshold Intervals

Goal: Increase the aerobic system’s ability to produce as much energy as possible without heavily relying on the fatigue-prone anaerobic system.

How: Get your heart rate up to the bottom of the red zone before beginning the interval. Once you’ve reached the red zone, work for 3-5 minutes while maintaining your pace and technique. Actively recover for 2-4 minutes down to your blue zone. Repeat for a total of 2-4 reps.

Exercises: Any cardiovascular exercise, particularly ones that are low impact, will work for this method.