Integrated exercise physiology showing muscle fibers, metabolism, heart rate, and VO2 max

Energy Systems, Heart Rate & VO2 Max

Connect muscle fibers, biomechanics, energy systems, heart rate, VO2 max, and resistance-training variables into one exercise-science framework.

Heart rate training zones for recovery, endurance, tempo, and high-intensity work

Heart Rate Zones: Training by Intensity

Learn how resting heart rate, maximum heart rate, heart-rate reserve, and training zones can help organize recovery, endurance, tempo, and high-intensity workouts.