Aerobic Exercise

The most exercise common mistake I see in my clinic is people who try too hard to lose weight through exercise. Most people know that aerobic exercise is the best way to lose weight. Unfortunately, many people think that if they push harder, they will lose weight faster. This is not the case. The “aer” in Aerobic refers to “air”. To exercise aerobically is to exercise at a pace that allows air to reach the muscles. For instance, if while you are exercising, you can talk without huffing and puffing, you are exercising aerobically. You know this because you have more than enough air to perform the activity. When you are gasping and panting, you are exercising anaerobically, or “without air”.

How does aerobic exercise help lose weight?
Fat burns in the presence of oxygen. Fat and oxygen together burn slowly, steadily and cleanly. An example of fat burning is a candle. With the right mixture of fat and oxygen, a candle can burn slowly and steadily for many hours without smoke. By contrast, paper (a carbohydrate) burns hotter, faster, and produces smoke and ash (byproducts of incomplete combustion).

When the demand for energy exceeds your oxygen supply, your body burns carbohydrate instead or in addition to fat. Burning carbohydrate produces a waste product called lactic acid (The waste product is like the smoke from burning paper). This acid is what makes your muscles “burn” during intense exercise. Lactic acid is also what makes your muscles feels sore and achy the day after intense exercise. Burning carbohydrate can also make you feel light-headed, exhausted and hungry after a workout. An aerobic workout like a brisk walk, is apt to make you feel invigorated and refreshed. You may be hungrier later, but immediately after the walk you are likely to feel energized by the increase in your metabolism.

Fat is a very efficient fuel. You can run a marathon on a half pound of fat. So how are you going to shed all those pounds by going for a half-hour walk each day? The beauty of aerobic exercise is that once you get your metabolism going, you will continue burning fat at an accelerated rate for the next 24 hours. You will burn extra fat while you sit, move, eat or sleep on the days you do aerobic exercise.

How hard should I exercise?

The simplest measure of intensity is to observe your breathing. If you are able to carry on a conversation while exercising, you are in your aerobic zone. If you are getting out of breath and your muscles are burning, you are moving out of your aerobic zone and into anaerobic territory. This method of evaluation is called “perceived exertion”. Frankly, if you’re not a competitive athlete, this is good enough.

How fast should my heart beat while doing aerobic exercise?

The following recommendation comes from the fact that for most people, your maximum heart rate equals 220 minus your age in years. So if your age is 20, then 220 – 20 = 200 beats per minute. If you are 70 years old, then 220 – 70 = 150 bpm. Remember, that’s maximum heart rate. Your training rate should between 50% and 85% of your maximum rate. So again, if you are 20 years old, your training rate will be between 100 and 170 beats per minute. To see your training rate (as endorsed by the American Heart Association), enter your age in the calculator below:

 

What if I’m new to aerobic exercise?

The American Heart Association recommends that you begin exercising at the low end of the training rate for your age. Use the Perceived Exertion Method to determine if you are exercising too hard or not hard enough. If you are getting light-headed, out of breath or feeling burning in your muscles, slow down. If it feels too easy, speed up. The only right intensity is what works for you. If you have a heart condition or are uncertain of the status of your heart, check with your physician before beginning any new exercise program. Also, if you are on blood pressure medications, your training rate will be lower.

How fast should my heart beat at rest?

For anyone over the age of 10, the normal range according to the American Heart Association is 60 to 100 beats per minute (the average is 72 beats per minute). Trained athletes normally have lower heart rates, typically in the range of 40 to 60  beats per minute. Tour de France winner, Miguel Indurain had a resting rate of 28 beats per minute.

Despite the American Heart Association guideline above, I recommend that your resting heart rate should not exceed 65 beats per minute. Why? Because studies have shown that there is a 10 – 20% rise in death rate for every 10 beats per minute over 65 bpm.(1) That same meta analysis found that “men with resting heart rates of over 90 beats per minute had an almost two-fold increase in risk for cardiovascular disease mortality; in women it was associated with a three-fold increase.”

One study of men with no evidence of heart disease but with a resting heart rate of more than 90 beats per minute had five times greater risk of sudden cardiac death.(2)

What if my resting pulse rate is abnormal?

First of all, check with your physician to find out why. In the meantime, let me provide a little information on possible reasons; Low pulse rate in non-athletes occurs in hypothyroidism, high blood pressure, weakness of the heart, inflammatory and autoimmune conditions and as the result of some medications. Low pulse rate in the elderly may be a sign of heart failure, particularly if it occurs in association with fainting, fatigue, cognitive issues and light-headedness. Coenzyme Q10 may be helpful for age-related slow heart rate because CoQ10 strengthens heart muscle by improving cellular utilization of oxygen. Note that statin drugs decrease production of CoQ10. For more on that, read my article on Cardiovascular and Metabolic Disease.

High pulse rate occurs in fever and hyperthyroidism.  I have seen pulse rates over 120 beats per minute at rest in acute hyperthyroidism. Rapid pulse rate can also occur as a result of lack of oxygen to the heart due to heart failure, atherosclerosis, pneumonia or other infections. Stress can raise heart rate temporarily, but it should not remain high for long.

Irregular heart rate can be caused by heart valve conditions such as mitral valve prolapse, over consumption of caffeine or prolonged stress, or imbalances in electrolytes (the minerals sodium, potassium, calcium and magnesium). Most Americans consume too much calcium and sodium, and not enough magnesium and potassium. The DASH diet recommended by the American Heart Association is designed to provide normal levels of electrolytes.

If your heart is beating too slow, too fast or irregularly, check with your primary care physician. When our hearts stop, so do we.

How do I measure my heart rate?

The best way to learn to measure your heart rate manually is to place two fingers on your opposite wrist, palm up, on the thumb side of the wrist. Alternately, you can place your fingers in the groove in the front of your throat, next to your windpipe. Feel for the pulse. When you are comfortable that you have found it, count while looking at the second hand of a clock so you can count all the beats in a full minute. With a little practice, try counting for 30 seconds and multiply by 2, or count for 15 seconds and multiply by 4. Ultimately, you will want to be able to get a good estimate by measuring for 6 seconds and multiplying by 10. To measure more conveniently, get a pulse measuring wristband or watch.

How long should I exercise?
A minimum of 20 minutes at your ideal pulse rate is sufficient to obtain the aerobic effect of burning calories at a higher rate for the next 24 hours. The longer you exercise, the more calories you burn but the most important factor is to exercise at least those 20 minutes every day. Be aware that it will very likely take you a little time to warm up to that heart rate and also to cool down with a milder version of your exercise. Therefor, it is best to allow at 30 minutes to do your daily minimum. You can always do more than the minimum to lose fat faster. Bear in mind that fitness is lost if you exercise 2 days or less per week. Fitness is maintained at 3 days per week and improved at 6 days a week.

What kind of exercise?
Walking, swimming, cycling, jogging, skating, skiing, jumping rope, rowing, running in place or on a trampoline, dancing or hiking are all good exercises because they require continuous, steady effort. Activities such as tennis, baseball or golf should be considered recreation rather than aerobic exercise because the effort is intermittent, characterized by bursts of anaerobic activity interspersed with periods of rest.

How do I know if I’m getting stronger?
The best way to measure your cardiovascular fitness is to monitor your pulse recovery rate. The way to do this is to take a six-second pulse immediately when you finish exercising and again exactly one minute later. The faster your heart is able to slow down after exercise, the greater your cardiac fitness. The formula to determine your recovery rate is to subtract your one-minute pulse from your end of exercise pulse and divide the result by 10. For example; if your heart rate as you finish exercising is 140 and your pulse one minute later is 100, 140 minus 100 = 40 divided by 10 = a recovery rate of 4. How does 4 rate? The following chart can be used as a guide:

Less than 2 Poor
2-3 Fair
3-4 Good
4-6 Excellent
More than 6 Super!

How do I know if I’m losing fat?
Muscle weighs more than fat, so the scale won’t tell you the full story. As you exercise, you increase your muscle mass. The more muscle you have, the more places you have to burn fat. You will know that you are losing fat by the way your clothes fit. If your waist is getting smaller, you are losing fat. To learn more about this read Take Charge of Your Waistline.

Conclusion:
Even if you don’t learn to measure your six-second pulse and you don’t care about your cardiac recovery rate, just get out and do at least 20 minutes a day of vigorous walking. If you can carry on a conversation, you have enough air. The benefits of exercise are tremendous. You will be feeling and looking better soon.

 

(1) The association between resting heart rate, cardiovascular disease and mortality: evidence from 112,680 men and women in 12 cohorts”. European Journal of Preventive Cardiology. 21 (6): 719–726.

(2)  Resting heart rate and risk of sudden cardiac death in the general population: influence of left ventricular systolic dysfunction and heart rate-modulating drugs”. Heart Rhythm: The Official Journal of the Heart Rhythm Society. 10 (8): 1153–1158

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