Walk into most fitness centers and you will find an area designated for aerobic exercise and another for anaerobic training. Treadmills, ellipticals and indoor cycles dominate the aerobic area while resistance machines, dumbbells and barbells are the central equipment for anaerobic exercise. You need to use both areas.
Let’s look at the difference. The energy for aerobic activities occurs when oxygen combines with carbohydrates or fats in the muscle to release energy. We don’t store oxygen, but it surrounds us and can be delivered. Aerobic exercises can be repeated many times, generally by a large portion of the body. Anaerobic exercises don’t require oxygen but use fuels already stored in the muscle. Strength training is anaerobic and usually designed for a specific body part. Strength exercises are short term, intense, often requiring only 30 or so repetitions for each body area.
We tend to think of aerobic exercise as healthy exercise, because oxygen must be delivered through the heart. Overwhelming evidence supports the positive impact on the heart, but aerobic training affects much more than the heart. The pulmonary system, the intricate vascular system, and the muscle cells where metabolism takes place all adapt to aerobic training. And what about stress relief, depression, a sense of control, and well-being? Multiple studies have shown the positive effects of aerobic training on mental health.
Aerobic training improves aerobic power, which is related to mortality. In one important study 13,000 men and women were evaluated at Aerobics Research Clinic in Dallas for a fitness evaluation. One important test was a maximal effort treadmill test. The test is simple; get on a treadmill at a fixed speed after which the incline is systematically increased until you have to get off. The sooner you get off the lower your aerobic capacity. Epidemiologists then tracked these subjects for years and found a significant relationship; fitter people live longer. Aerobic power was related positively with all-cause mortality, not just heart disease. More importantly, you didn’t have to be super fit, you just had to be out of the bottom 20-percent to receive a profound benefit. In fact, the relative risk of being in this very unfit group was greater than smoking, high blood pressure, and a family history of heart disease.
When you improve or maintain your aerobic capacity you also open the door to opportunity. Exercise scientists have documented the energy requirement for all forms of activity. Fit or unfit, the energy requirement is the same. We know exactly how much oxygen it takes to walk, run, swim, cycle and play tennis. Domestic activities like ironing, gardening and raking have been quantified. Want to stand in a river and fish? Dance? Paddle a canoe? All these take energy and when you lose aerobic capacity you systematically erase those things important to your quality of life.
Playing most sports requires both strength and endurance. There is little question that strength training improves performance and helps prevent injury. Since most sports are played while standing, and the fact that most injuries occur to the lower body, good leg and hip strength are very important, especially if you want to compete as you age. Resistance training in the weight room is a good start but you also need higher speed resistance such as sprinting and jumping.
For most of us, we tend to lose strength as we age, especially if we are inactive. Participating in some resistance exercises can mitigate this. Like aerobic power, losing strength can also reduce our quality of life. Kayaking is an aerobic activity, but picking up the kayak requires strength. Like to travel? You need to carry your suitcase. And what about independence, the ability to take care of your own needs, shoveling snow, moving furniture, getting out of a chair? Strong people don’t fall as easily. Having a strong body is one key to independence.
Fitness training does not have to take over your life to reap benefits. Fitness training is not a job, but something to add to your life. Don’t become obsessed with fitness. Getting out of the bottom 20-percent is not that difficult. A walking program will do that. I have performed resistance exercises for the past 50 years, but I don’t strength train all year. I frequently take breaks of six weeks or so. The effects of strength training lasts for weeks. Maintaining good strength and endurance allows you to continue living at your best.
Jim Johnson is a retired professor of exercise and sport science after teaching 52 years at Smith College and Washington University in St. Louis. He comments about sport, exercise, and sports medicine. He can be reached at jjohnson@smith.edu