Zone 1 (50-60%): Active recovery, light warm-up, improves overall health
Zone 2 (60-70%): Fat-burning zone, builds aerobic base, conversational pace
Zone 3 (70-80%): Aerobic cardio, improves cardiovascular efficiency
Zone 4 (80-90%): Anaerobic threshold, increases lactate tolerance
Zone 5 (90-100%): VO2 max, peak performance, short intervals only