Chasing Max Heart Rate? Here’s Why You Might Want to Slow Down

Tracking your heart rate during exercise can maximize the effectiveness of your training and unlock significant performance gains. But more intensity doesn’t always mean better results. In fact, exercising at a moderate pace can offer many health and fitness benefits.

What Are Target Heart Rate Zones?

Smart watches and fitness trackers have made it easy to track heart rate and monitor performance while exercising. The ideal heart rate zone is different for everyone and depends on your fitness goals. There are generally five heart rate zones, which represent a percentage of your maximum heart rate:

• Zone 1 is low intensity, at 50-60 percent of maximum heart rate. A brisk walk, for example.
• Zone 2 is moderate intensity, at 60-70 percent of maximum heart rate. Light jogging, for example.
• Zone 3 is moderate to high intensity, at 70-80 percent of maximum heart rate. Steady running or cycling.
• Zone 4 is high intensity, at 80-90 percent of maximum heart rate. Sprinting or vigorous interval training.
• Zone 5 is short bursts of very high intensity, pushing your heart to 90-100 percent of maximum rate.

Zone 2 is a good place for most people to spend the bulk of their workouts, says Laura Goldberg, MD, University Hospitals adult and pediatric sports medicine specialist. “Lower intensity, zone 2 exercise, uses fat for fuel. This is a good zone to start an exercise program as well as to improve cardiovascular health,” says Dr. Goldberg.

How to Calculate Your Ideal Heart Rate Zone

Your maximum safe heart rate is about 220 beats per minute minus your age. If you’re 45, your maximum rate would be 175 beats per minute. So the range from moderate to high intensity (let’s say 60 percent to 85 percent) would be approximately 105 to 148 beats per minute.

If you don’t use a tracker, a simple way to gauge intensity is called the talk test. With moderate exercise, you can talk, speaking three to five words without taking a breath, but you’re unable to sing. In zone 3, conversation becomes difficult.

If you take medication that affects your heart rate, that could change your maximum heart rate calculation.

How Varying Heart Rate Zones Can Improve Performance

“When you vary your exercise intensity with different heart rate zones, you train your body to make specific physiological and metabolic adaptations,” says Dr. Goldberg.

For example, exercising in zone 2 is low enough intensity to stimulate muscle adaptations that improve the use of fat as a fuel source, sparing carbohydrates. “Training in zone 2 allows the body to switch from one source of fuel to another,” says Dr. Goldberg. “As a result, a marathon runner that trains in higher zones 4-5 without a good base of zone 2 training will not be as efficient at using fat as a fuel.”

In fact, someone training for a marathon should spend around 80 percent of their running time in lower-intensity zones, even though it may not feel intense enough.

Higher intensity exercises rely more on carbohydrates and protein for fuel. Training for a shorter, high-intensity activity requires longer intervals training in higher zones. Zone 5 training develops anaerobic endurance, which increases speed and power and can improve maximum oxygen absorption.

“High-intensity training uses carbohydrates as a source of fuel, which is in limited supply in our bodies, so we can’t sustain zone 5 training over long periods of time,” says Dr. Goldberg. “Also, if not given appropriate recovery time, it can lead to elevated cortisol levels, which increases stress on our body and affects performance.”

Repeated, short bursts of activity for 30 seconds or less, followed by one to three minutes of recovery, should be followed by a recovery day and not done more than two to three times per week, says Dr. Goldberg.

Make a Plan

Targeting different heart rates zones for specific periods of time depends on what you’re training for and what your goals are. Training plans generally call for time spent in both high- and low-heart rate zones. A sports medicine specialist can help design a personalized plan for you based on your physiology and your goals.

If you take medication or have a heart condition, you should talk to your doctor about setting heart rate zone goals.

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The sports medicine specialists at UH Drusinsky Sports Medicine Institute provide athletes of all ages and skill levels with the tools and medical support they need to reach their fitness goals.