Do I Burn Less Fat if My Heart Rate Is Too High While Exercising?

Do I Burn Less Fat if My Heart Rate Is Too High While Exercising?
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The target zone has become a buzz word for people wanting to lose weight through exercise. Many trainers used to advise exercising at a lower intensity to burn more fat. This is only partly true. When your heart rate is lower, your body will use a greater percentage of fat as an energy source. But at a higher intensity, you'll burn more calories overall.

Fat Burning and Aerobic Zones

When you exercise at low intensities, fat accounts for most of your energy expenditure. As your heart rate increases, you burn a higher percentage of carbohydrates. According to the American Council on Exercise, higher-intensity exercise will result in greater weight loss. It doesn't matter whether your body is burning carbohydrates or fat. In addition, a higher intensity will keep your metabolism elevated for longer, so you'll burn calories even after you stop.

Reaching Lactate Threshold

Your lactate, or anaerobic, threshold is the point where your body can't supply adequate oxygen to your muscles. After this point your body burns exclusively carbohydrates. High intensity workouts are effective for burning a large number of calories quickly. However, lactic acid begins to build up in your blood, your muscle carbohydrate stores begin to get depleted and you might fatigue rapidly. Sports coach Brian Mac says your lactate threshold can be between 50 and 90 percent of your maximum heart rate, and increases with training.

Calculating Target & Maximum Heart Rates

You can estimate your maximum heart rate by subtracting your age from 220. For example, if you're 40, your MHR will be roughly 180. The Cleveland Clinic advises that you'll gain most benefits from exercise at between 60 and 80 percent of this rate. Avoid exceeding 85 percent, as this can cause added cardiovascular risks. When exercising, stop occasionally and measure your pulse by pressing two fingers lightly on your wrist. Count the number of beats for 30 seconds and multiply by 2. Alternatively, wear a heart rate monitor to measure your intensity of exercise.

Exercising To Lose Weight

The Department of Health and Human Services recommends 150 minutes of moderate aerobic activity per week. If you're trying to lose weight, you might want to exercise more, as well as eating a healthy diet. One option for maximizing fat loss is interval training. Alternate five minutes of vigorous exercise at the higher end of your target zone, with two minutes at a lower intensity. Another good option is running or cycling for longer periods at a low to moderate intensity. If you're not used to exercising, build up to your target rate gradually. If you have a heart condition or other health problems, consult your doctor before beginning an exercise routine.

References

Article reviewed by Geoffrey Darling Last updated on: Sep 1, 2011

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