Training Talk: Should You Do HIIT or LISS Cardio?

In my fifteen years as a coach, one question comes up the most. Everyone asks: Training Talk: Should You Do HIIT or LISS Cardio? This is not a simple yes-or-no choice. It is a balancing act between your energy and your recovery.

HIIT uses short, hard bursts of effort. You reach 85-95% of your peak heart rate. Then, you rest. LISS, or “Zone 2” cardio, keeps your heart rate steady. You stay at 60-70% of your peak heart rate.

The American College of Sports Medicine (ACSM) notes that neither style is “better.” They just trigger different results in your body. HIIT helps your VO2 max quickly. LISS builds your capillary density and mitochondrial health.

The Truth About the “Afterburn”

Many ads talk about the “afterburn” effect. Science tells a different story. Studies in the Journal of Strength and Conditioning Research show the truth. This burn accounts for only 6-15% of your total energy used. Do not base your entire plan on this effect alone.

Choosing the Right Path for Your Goals

If you want to build muscle, I suggest LISS. It causes very little fatigue to your nervous system. This lets you lift weights more often.

Are you short on time? Two HIIT sessions a week can boost your health. You get great results without the exhaustion of daily high-intensity training.

The Gold Standard: A Balanced Approach

Most experts agree on a specific model for success:

• 80% Low-Intensity Training: This builds your aerobic base.
• 20% High-Intensity Training: This pushes your cardiovascular limits.

This 80/20 model is the gold standard for long-term health. It helps you stay fit while keeping your body ready for your next workout. Use this mix to see the best results over time.