Stress Mastery : The Benefits of Exercise & Types of Exercise

The Benefits of Exercise

Is there proof that exercise helps to cope with stress? Research clearly indicates that exercise is an effective stress reducer. Indeed, many studies have found that one of the most reliable differences between individuals with high and low levels of stress resistance was exercise and activity level (for example, see Brown, 1991; Kobasa,, Maddi, & Puccetti, 1982; and Roth & Holmes, 1987, just to name a few). In one study, McGilley and Holmes (1989), found that individuals who exercised regularly had lower cardiovascular and subjective responses to psychological stress than individuals who were not physically fit. Studies have also been done linking regular aerobic exercise to reductions in depression (McCann & Holmes, 1984), anxiety (Long, 1984), and improvements in self-esteem (Sonstroem, 1984). In addition, research has shown that exercise bolsters energy resources rather than consumes them. In a clever study carried on over a twelve-day period by Thayer (1987), subjects either ate a candy bar or took a ten-minute walk during the afternoon lull when people often feel tired. Those who ate the candy bars reported a short-lived boost of energy, but within an hour they were even more tired and tense. The walkers, on the other hand, felt increased energy and decreased tension for up to two hours after the walk. Furthermore, it is important to note that the amount and intensity of exercise necessary to produce stress-management effects need not be overly extensive.

Research suggests that regular exercise, even of only moderate intensity, provides a dress rehearsal for dealing with stress. Why is this the case? Because the way your body responds to exercise is very similar to the way your body reacts to stress. During exercise your heart rate increases, blood pressure rises, respiration quickens, stress hormones are released, and muscles tense to perform the activity. Does this sound familiar? Therefore, engaging in regular exercise gives your body practice in experiencing stress, allowing you to develop more strength and stamina to cope; therefore, your body can recover faster from stress. The theory of cross-reactivity postulates that regular exercise teaches your body how to recover more readily from emotional stress as well—that is, you become conditioned to handle stress more effectively due to repeated exposure to the stress of exercise.

It appears that the stress-reducing effects of exercise are both short and long term. Many people find a single exercise session to be an excellent way of releasing tension. Proponents of regular exercise who exercise at least three times weekly typically report lowered levels of tension overall, even on days when they are less active (Holmes & Roth, 1988).

There is ample proof of the benefits of physical activity and exercise for health and longevity. A landmark longitudinal study (Paffenbarger et al., 1986) of 17,000 Harvard University graduates revealed that graduates who walked nine miles or more per week had a 21 percent lower risk of death than those who walked less than three miles per week. Those who burned less than 2,000 calories per week in physical activity had a 38 percent higher risk of death than those who burned more than 2,000 (the exercise equivalent of jogging approximately 20 miles a week) calories per week. The active alumni lived two years longer, on average, than their more inactive counterparts, who also had the highest risk of heart attacks. An English study by Morris et al. (1953) found a strong relationship between cardiovascular disorders and physical activity among postal and transportation workers. Letter carriers, who walked daily, and bus conductors, who were continually in motion collecting tickets, had about half the rate of heart attacks of postal clerks and bus drivers, who spent most of their workday sitting.

Another experiment with monkeys (Kramsch et al., 1981>) confirmed the cardiovascular benefits of vigorous, sustained exercise, even when diet was far from ideal. Three groups of monkeys were randomly assigned to the following conditions: (1) a sedentary group that received a low-fat diet; (2) another sedentary group fed a diet high in fat and cholesterol; and (3) an active group that exercised for an hour on a treadmill three times weekly and were also fed a diet high in fat and cholesterol. The animals were monitored over a three-and-a-half year period. The active monkeys, despite their unhealthy diet, had higher levels of “good” (high-density lipoprotein—HDL) cholesterol (which is linked to cardiovascular health) and lower levels of “bad” (low-density lipoprotein—LDL) cholesterol (which is linked to cardiovascular disorders) than their sedentary counterparts. In addition, arteriosclerosis and sudden death were significantly more frequent occurrences among the two groups who did not exercise.

Clearly, exercise has powerful positive effects on both our psychological and physical well-being. Table 1 lists some of the most notable cumulative benefits of regular exercise.

But is all exercise the same in terms of its effects on managing stress? Research has found that just about any kind of physical activity can help reduce stress. This is because exercise exerts its stress-management benefits in numerous ways. Exercise induces biochemical and physiological changes that help your muscles relax, help you recover faster from emotional stress, and provide health benefits that counterbalance the negative effects of stress. Because of the pain and strain inflicted on your body by exercise, chemicals known as beta-endorphins are released in your body. Endorphins, which are chemically quite similar to morphine, are your body's natural painkillers. These chemicals appear to help your body recover from prolonged exercise by raising your pain threshold, slowing your heart rate, and decreasing your blood pressure, while enhancing your parasympathetic response (which leads to the relaxation response) and simultaneously inhibiting sympathetic activity (the fight-or-flight reaction). Physical activity can also provide a welcome diversion from sources of stress, as well as relieving boredom and providing opportunities for social interaction. Exercise is often fun, and enjoyable activities help reduce your stress level. Exercise may help you feel better about yourself by improving your health, fitness, and appearance. And mastering a new skill or excelling in a sport can also improve your self-esteem.

Types of Exercise

Exercise represents one type of physical activity. In general, physical activity includes all kinds of movement—from cleaning your house, carrying bags of gro ceries, mowing your lawn, and rocking a baby to the more structured workouts we associate with exercise or playing a sport. Exercise generally refers to physical activities performed intentionally to improve physical fitness or to control weight. Physical activity occurs because you need to get something done that requires movement and energy. But in reality all physical activity could be considered a form of exercise. Let's consider the different types of exercise. Physical activity can be divided into three broad categories: aerobic, anaerobic, and low-intensity exercise.

Aerobic Exercise

One type of exercise clearly linked to stress reduction is aerobic exercise. This involves the sustained, rhythmic activity of the large muscle groups, particularly the legs. In order to qualify as aerobic, an activity should significantly increase your metabolic rate for a prolonged period of time (fifteen minutes or longer) (Fixx, 1977). Popular aerobic exercises include running, jogging, brisk walking, in-line skating, swimming, cycling, cross-country skiing, and aerobic dance. Which aerobic activity you choose is not nearly as important as whether you do it regularly. Aerobic exercise uses up a large volume of oxygen. This increased demand for oxygen leads to increases in heart rate and respiratory rate, along with a relaxation and dilation of the small blood vessels (capillaries) to allow more oxygen-carrying red blood cells to travel to your muscles.

Aerobic exercise improves fitness and facilitates stress mastery because of a phenomenon known as the training effect, in which your cardiovascular system is strengthened along with your stamina. To produce the training effect, you need to engage in nonstop, aerobic activity for at least twenty minutes three to four times a week. You know that your aerobic fitness has improved when you can perform a given amount of work (such as climbing several flights of stairs) with less effort. Ideally, to produce the training effect, your heart rate should reach 70 percent of the maximum range appropriate for your age and remain at that rate for twenty straight minutes. Exercising below your aerobic heart rate will not create the training effect, and activity consistently above your recommended heart rate could put too much strain on your heart. Staying at the 70 percent level places moderate stress on your heart, which gradually will improve its efficiency.

To determine your recommended range based on your age, first you must determine your recommended maximum heart rate, the fastest that your heart should be beating. If you are free from cardiac problems you can determine this by subtracting your age from the number 220. In general, your maximum recommended heart rate decreases with age at the rate of one beat per year. Your recommended target heart rate for sustained exercise is 70 to 80 percent of your maximum heart rate. First, multiply your maximum heart rate by 0.70 to get the low end of your target range; then multiply it by 0.80 to determine the high end.

During cooldown from an aerobic workout your muscles can relax. One study found that aerobic activities such as walking, jogging, and bicycling reduced muscle tension by more than 50 percent for up to ninety minutes following the workout (deVries et al., 1981). Likewise, rhythmic aerobic activity such as rowing, swimming, walking, and running has been shown to increase alpha-wave activity in the brain (Stamford, 1995). Alpha brainwaves are associated with mental and muscular relaxation. The cardiovascular fitness that results from regular aerobic exercise reduces the risk for heart disease. Aerobic exercise increases HDL (high-density lipoprotein—the “good cholesterol”) levels in your bloodstream. HDLs appear to transport cholesterol out of your arteries, helping to prevent artery disease. Aerobic activity also increases insulin sensitivity, thus stabilizing blood sugar levels and decreasing the risk of type 2 diabetes. Regular aerobic exercise helps prevent high blood pressure, and helps reduce hypertension in those already afflicted. Aerobic exercise also makes blood platelets (which are responsible for blood clotting) less likely to clump together, reducing the risk of obstructive blood clots (which could lead to heart attack or stroke).

Anaerobic Exercise

Anaerobic exercise, such as team sports, individual sports such as tennis and racquetball, or track-and-field activities, can be quite exerting, but basically consist of stop-and-go action. Bursts of speed and specific movements are followed by periods of virtually standing still waiting for the next play to begin. Although anaerobic exercise can burn many calories along with improving flexibility or specific skills, the training effect will not occur unless you engage in the activity for twenty minutes nonstop. Although activities such as bowling, archery, or golf, do not call for the level of vigorous physical action required in aerobic activity, they still have been associated with stress reduction. When you are actively engaged in tasks that demand your concentration and attention to motor skills, it is hard to keep your mind on your worries. Engaging in such activities is often a lot of fun and may provide opportunities for socializing. Any activity that is enjoyable and promotes social support is potentially stress-reducing.

Low-Intensity Exercise

Low-intensity exercises are geared to increase flexibility and strength. These activities are not vigorous enough or engaged in for a long enough period of time to promote the training effect; nevertheless, they can be potent stress reducers. There are three main varieties of low-intensity exercises:

All forms of exercise are potential stress reducers and each has specific applications. Clearly, aerobic exercise helps us manage stress because it increases our stamina and energy while releasing muscular tension. Anaerobic exercise does not necessarily improve stamina, but it too can help release muscular tension. Most of us engage in anaerobic pursuits because they are something we enjoy (for example, a rousing game of tennis or shooting hoops with friends), and engaging in any enjoyable, entertaining activity helps to counterbalance the stresses in your life. If you work hard, you may also need to play hard. Low-intensity exercises such as stretching are vital for stress reduction. Many ancient systems such as yoga or tai chi, which use sophisticated stretches and movements, are wonderful stress reducers, due to both their meditative aspects and muscular release. Progressive relaxation is basically a system of isometric exercises geared toward decreasing muscle tension. Even isotonic exercises such as weight lifting can be very useful for releasing pent-up muscular tension.