Regular aerobic exercise may decrease your risk of death by 15% and add 3 years to your life. Effectiveness of exercise depends on what you do—1 hour of walking versus P90X requires very different amounts of energy expenditure. Heart rate monitors help gauge how much you are exerting yourself and potentially how much benefit you are going to get. They can be purchased as watches that often have a strap that goes around the chest, although some newer ones may not need a strap. Often they can be added as accessories to modern smartphones. Most of these are now wireless, making them much less cumbersome. Costs vary from under $100 to up to $500 depending on the features. Higher end treadmills and ellipticals often have heart rate monitors imbedded into the handles.
These monitors can be helpful with any type of aerobic exercise such as jogging, biking, elliptical training and even swimming (find one that is waterproof not water resistant). To use your heart monitor effectively you first need to know your maximum predicted heart rate. This is estimated by subtracting your age from 220 for men and 226 for women. You then know your theoretical maximum heart rate in beats per minute. Now pick your sport and set up training zones. These can help you achieve your goals and prevent both under and overtraining.
I’ll share how I use this. I like running. At 42 years of age, my maximum heart rate calculates to 178 bpm (beats per minute). My training goal is to prepare for half/full marathons. This requires endurance training (ability to go long distances with moderate energy expenditures). So for most of my training I will want to be in the ‘aerobic zone’. In this zone, the body’s primary energy stores are in the form of glycogen. When you do aerobic exercise the body does not have to go into ‘back up stores’ to create energy. Higher intensity training for long periods of time forces your body into the ‘anaerobic zone’ where the body then has to look for alternative sources of fuel which could result in muscle break down.
So if I go out on a training run I will want a target heart rate between 125 to 142 bpm. Typically I will find a pace at which my heart rate remains around 135 bpm, and I feel comfortable. Once I find that pace, it is amazing how constant the heart rate remains. Because my main goal is endurance training, this is where the bulk of my exercise focuses, but say I want to work on speed. This can help me finish a race or help on hills when the ‘extra push is needed’. I will mix it up by running ¾ of a mile at a lower heart rate goal of say 120 bpm (67% or 2/3 of maximum) and then finishing the remaining ¼ mile at 160 bpm (90% of maximum), then repeating this for several miles. This gets my heart rate into the anaerobic zone and allows me to work on speed but not long enough that I start to tear down my own muscle.
If just starting an exercise program, you will want to start with a lower target heart rate like 50-60% of maximum and then build upwards as your body gets in better shape. For weight loss, you can target 60-70% of maximum heart rate with exercise 4-5 days, per week 45 minutes at a time. Then as you get hooked on fitness, you will want to increase to the aerobic zone at 70-80% of maximum to gain endurance and strength. As I previously explained, pushing into the anaerobic zone at 80-90% can be helpful in building speed/finishing power. But if you see yourself constantly in that zone, you will want to pull back a little to avoid overtraining, injury, or breakdown of muscle.
As you get in shape, you should also notice your resting heart rate decrease as your heart is now more efficient. It may also take more effort to get in the right training zone which is a sign that your body is ready for more vigorous physical exercise.
All of this heart rate monitoring can lead to some compulsiveness. I recommend 1-2 times per week that you just go out and exercise with the monitor off. Exercise at a level where you feel good, and forget about the heart rate. Enjoy staying healthy!
Jeffrey N. Whitehill, M.D.
