Have you ever wondered how to train aerobically to most efficiently lose body fat? I get a lot of questions about aerobic exercise training, and it seems that there are many misconceptions about how to train effectively, so I want to clarify some points.
Years ago, we instructors were taught to encourage our clients to stay in their “target heart rate range.” This range is also called your “target zone” or your “aerobic heart rate range.” This range simply gives you the number of times that your heart should beat per minute while exercising aerobically. The number represents about 60% to 80% of your heart’s maximum capacity. We were taught that this is the range in which we most efficiently use fat as a fuel source for exercise. Hence, the mantra, “lower intensity, longer sessions,” was drilled into aerobics instructors everywhere as the way to help clients burn body fat.
For my clients that have heart disease or any other cardiovascular complication, I encourage the use of a heart rate monitor that is worn strapped around the chest. This will provide an up to the minute, accurate reading of your heart rate. This population needs to be careful not to exceed 70% of their maximum heart rate without permission from their cardiologist.
As exercise scientists researched the idea of the target heart rate range being optimal for cardiovascular training and burning body fat, new data has emerged that challenges this paradigm. Rather than low-intensity, long duration aerobic training, short intervals of 30-90 seconds produce substantially more fat loss. These short “bursts” are interspersed with short periods of baseline, steady state training during which you can catch your breath and gear up for the next interval.
You see, during strenuous exercise the rate of metabolism rises, going to about 15x the basal metabolic rate and even higher during intense interval work. Research shows that by maintaining a high level of training over a 5-6 week period, you can expect a significant increase in the ratio of lean body mass to fat. This means that you will increase muscle mass and decrease body fat very efficiently.
Intense interval work uses a greater percentage of the body’s muscles, and the high intensity work places added energy demands on the respiratory system, cardiovascular system, and nervous system. As such, more fat and glycogen are burned to support the expanding energy demands of the body both during an after intense exercise. A simple way of looking at it is this: lower intensity exercise burns a greater percentage of fat per calorie, but higher intensity exercise burns more total calories and thus more total fat.
In addition, your metabolic rate remains elevated longer after your workout when you exercise at a higher intensity. If you have coronary disease, interval training is not a recommended training protocol. For healthy older adults with a reasonably good level of aerobic fitness, it should not be a problem to do interval training, but always get clearance from your doctor. It would be a good idea as a safety measure to take a treadmill stress test to be sure that there are no cardiac abnormalities.
Hope that this information is useful!
Live with Simplicity,