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Training With Heart Rate: Zone 4

A heart rate “zone” is a percentage of your max heart rate. Within each “zone”, your body is doing different things to meet the energy demands of that output.

Over the next few days, I’m going to share what each heart rate zone means; how often you should work out in that zone, and how we use that zone to maximize your results.

Zone 4 occurs at 85-91% of your max heart rate. This might feel like an all-out effort, and it’s best done with a partner or group.

In Zone 4, you’re feeling the burn (lactic acid) and you feel like you’ll have to stop soon. Your heart rate will feel like it’s racing, but it can go a little bit harder. You’re burning energy very fast, so you’re primarily using stored carbohydrate, not fat.

Training in Zone 4 will help you buffer lactic acid. You’ll become more efficient at removing waste from your muscles, but also at tolerating the pain you get from hard work. All those slogans that say stuff like, “If it doesn’t challenge you, it doesn’t change you?” They’re talking about Zone 4 and above.

Training in Zone 4 will make you better at competing in aerobic events, so if you have a run, swim or cycling event coming up and you want to get faster, you should do more training in Zone 4. On the flip side, training in Zone 4 will delay the onset of Zone 5. I’ll talk more about that tomorrow.

Interestingly, Zone 4 training might improve mitochondrial efficiency and density. This is like adding little batteries to your body: you’ll have more energy and fight disease harder.

The best way to train at this level of intensity is with a group of friends. We call this “collaborative competition” – everyone wants to beat their own fastest time at the workout, but you’re using the group to push yourself harder. If you’re doing a HIIT (high intensity interval training) or MMIT (multi modal interval training) workout, I strongly recommend you do it with a partner or a small group.

This type of workout can feel like a game, or even sport. CrossFit’s mantra (constantly varied functional movements at high intensity) mostly refers to Zone 4 and Zone 5 workouts. And this all-out exercise is beneficial, particularly combined with strength training and Zone 2 workouts. In general, we recommend at least two workouts in Zone 2 for every workout in Zone 4 or above to maximize fat loss, energy metabolism and long-term health.

Watch: zone 4 video