Even Hippocrates, who lived in 400 B.C. and is considered the father of scientific medicine, understood the benefits of physical activity. Hippocrates recommended that food intake and exercise should be balanced for good health. Since then, much effort by physicians and scientists has been devoted to understanding the benefits of exercise to prevent and treat disease.
Here, we answer eight important questions about exercise and its health benefits.
1. Exercise, physical activity and fitness: What's the difference?
- Physical activity is simply any bodily movement performed by the muscles that expend energy. This includes all the movement one does throughout the day, whether it be intentional, part of one's job/occupation or simply for transporting one's self from one place to another. All activity and steps count toward your health.
- Exercise is a subset of physical activity that is planned and structured with the purpose of improving or maintaining physical fitness or health. In general, exercises are divided into activities that are predominantly aerobic (like running) or resistance (like weight lifting), although most sports and physical activities have components of both.
- Fitness is the ability to perform activity at a moderate to vigorous level of intensity without tiring easily. Metabolic Equivalent of Tasks, or METs, are commonly used as the unit attributed to different activities to describe the intensity and the amount of energy spent in that activity. The more fit you are, the more physical activity you can do and then the more oxygen the body uses to meet the energy demands. METs can be measured during an exercise (treadmill or bicycle) stress test, and they are commonly performed at a doctor's office to investigate cardiac or pulmonary disease. Fitness also depends on your age, sex, body size and genetic background. But it's clear that regular physical activity improves your fitness level.
2. What intensity exercise should I do?
If you hate running, no worries! Exercise does not have to be vigorous to be heart-healthy. In fact, nearly all cardiovascular benefits are gained by moderate-intensity activity. There may be further gain, particularly for fitness, by adding vigorous activities. But even light activities, particularly if they replace sitting or sedentary time, also provide health benefits.
Light activities include leisurely walking, light stretching, light housework and gardening.
Moderate activities include brisk walking, leisurely bicycling, dancing, swimming and moderate housework or yard work.
Examples of vigorous activities are running, aerobics classes, competitive sports, more intensive cycling and hard physical labor.
3. How much exercise do I need?
Several groups, including the Centers for Disease Control and Prevention and the American Heart Association, released guidelines recommending that adults should engage in moderate-intensity exercise lasting at least 30 minutes on at least five days of the week. The American Heart Association specifically recommends at least 150 minutes per week of moderate-intensity activities, or 75 minutes a week of vigorous activity, or any combination in which one minute of vigorous activity counts towards two minutes of moderate-intensity activity.
This generally can be achieved by brisk walking for 30 minutes or running for 15 minutes on most days of the week, or swimming for 50 minutes at a leisurely pace three days a week.
Strong data supporting these minimum levels of exercise comes from multiple studies that followed thousands of subjects of different sexes, ages and ethnicities for many years. One large study combined data from several studies and found that this level of activity decreased the risk of dying by 20 to 30 percent (1 out of every 4 deaths prevented) over a 12-year period. Although the data appear to show that more intense or more prolonged exercise may provide a greater benefit, other studies (in older subjects) showed that even one hour of exercise a week (like walking or riding a bike) or walking six to12 blocks weekly reduces the risk of having a heart attack.
As with other things in life, some things that work for someone else does not mean it will work for you. In general, the amount of exercise you do should be tailored to your current fitness, your health, your schedule, medical conditions and the goals and benefits you want from exercise.
If you think you can't exercise because of health concerns, discuss this with your health provider. There are very few circumstances when one isn't able to exercise at all. Even small amounts of exercise once or twice a week may help you to be healthier. Brisk walking is an activity with a low risk for injury that most adults can do without medical clearance.
4. Do I have to exercise every day?
While it is generally advised to spread activity throughout the week, even if you can only find time to be active on weekends, any level of activity is beneficial.
In a recent study that included over 60,000 middle-aged participants, those who met their total physical activity recommendations in only one or two sessions per week (i.e. weekend warriors) enjoyed similar benefits ,such as lower risk of dying from any cause and dying from cardiovascular disease or from cancer, compared with those who exercised in moderate amounts spread through most days of the week. Both groups had better outcomes compared with those who were inactive.
5. Is there such a thing as too much exercise?
Although there have been suggestions about the adverse health effects of strenuous exercise, this remains a topic of debate among physicians and scientists who study this field. What we know today is that people who perform strenuous exercise may not get additional incremental benefits compared with those who exercise at moderate amounts regularly. However, some of these individuals may have individual susceptibility factors (specially undiagnosed cardiovascular disease) that could increase their risk of harm from strenuous exercise. Certainly lack of exercise among U.S. adults is more of a health concern than too much exercise.
6. Why is physical activity beneficial?
Many parts of your body, including your brain, heart, bones and joints, feel the positive effects of exercise. Some of the best-known effects of exercise are on the heart and the cardiovascular system. We know that the hearts of athletes grow and beat stronger than people who aren't athletic. This is caused by the heart cells increasing in size, increasing numbers of cells in the heart (because the stem cells become active and make more cells), and because more arteries grow to deliver more oxygen and nutrients to the heart. This process is different than the growth of scar and nonfunctional tissue that takes place in a so-called enlarged heart when the heart is ill. These positive changes in athletes' hearts likely contribute to preserving function as the heart ages. Exercise also induces the release of molecules from the arteries, which have protective effects against developing atherosclerosis (fatty plaques that block arteries), responsible for heart attacks.
Physical activity has mild beneficial changes in the blood lipid levels. This applies to the bad cholesterol (LDL), good cholesterol (HDL) and triglycerides. Although these changes are small, it's believed that they're meaningful in reducing the risk of developing cardiovascular disease.
Exercise and physical activity also have beneficial effects on blood pressure. Although these changes are modest, they're consistent. It's not clear, however, if low or high intensity exercise helps best with this.
There are also data to support that exercise can help control diabetes and probably prevent it by contributing to weight loss, but by also directly improving how one's body responds to insulin.
How exercise affects body weight deserves an important mention. The level of energy intake versus energy expenditure significantly affects total body weight and body composition. This is known as the energy balance, and although it is not the sole regulator of body weight, it does play a major role in its regulation. When you exercise, the body is using energy (stored as glycogen and fatty tissue). If the body uses more energy that it takes in (in the diet), the energy balance is shifted and the body loses weight. Results of research studies have suggested, however, that the amount of physical activity needed to lose weight is significantly higher than the minimum needed to improve the risk of disease. To lose a significant amount of weight (over 5 percent) without specific dietary changes, studies have estimated that you would need to exercise ~5 hours a week of the equivalent of moderate-intensity activities. On the other hand, if the exercise regimen is combined with a diet containing less calories (such as ingesting 500 fewer calories a day), less exercise is needed (closer to recommended minimal amounts) to achieve weight loss.
7. Is one type of exercise better than another?
Probably not. The best exercises are the ones you enjoy and are willing to do consistently—something you look forward to that's seen as fun and not a chore. Even better if you switch up the type of exercise to break monotony! There are so many options for fitness. We recommend engaging in complimentary activities such as combining cardio with strength training.
In a large study published in 2016 in the British Journal of Sports Medicine, researchers found that individuals from England and Scotland participating in swimming, racquet sports and aerobics had a lower risk of death from cardiovascular disease. These sports plus cycling were also associated with lower risks of death from any causes. The comparisons were performed against subjects not performing these activities. But, the study was limited in that other types of sports they analyzed had too low participation to be conclusive. As an example, although this study couldn't confirm survival benefits for runners, other studies have demonstrated this.
There isn't any definitive evidence that one sport is better than another. Just get moving! There is no need to belong to a gym and have access to fancy machines to take advantage of what exercise can do for you.
8. Tell me some other fun facts about exercising.
Interesting studies comparing the bone structure of primates, human ancestors and humans indicate that our bones are getting lighter with time and more prone to fracture, likely related to the decreased levels and intensity of physical activity of our modern lifestyle compared with the physical activity needed to chase prey and gather food. We also know that humans who perform more exercise have stronger bones than the ones who barely exercise, so exercising is good to increase your bone strength and decrease the risk of fractures.
Scientists have also discovered, that at least in mice, exercise in older mothers can decrease the risk of their babies having certain heart defects at birth, suggesting that the more exercise women do, especially if they're older, may help decrease the risk of birth defects in their babies.
Exercising helps the body release many hormones, including one likely associated with learning and cognitive abilities, possibly making you feel sharper and smarter.
A recent study in a varied group of subjects from New Zealand, showed that people who considered themselves to have "optimal well-being" (high scores in questionnaires about happiness, emotional stability, vitality, optimism, self-esteem, competence and positive relationships, among others) were more likely to exercise regularly.
Exercising also decreases your risk of dying from cancer.
So, as you can see, there are many factors that are positively affected by exercise that work together to help you improve and prolong your life. There are likely other benefits, too, that we may have not discovered yet that also contribute to helping you live healthier and longer. So make time to move a little more every day: It's worth the effort!