How Much Exercise Do You Need For Health Benefits?

Exercise is so effective at preventing and treating certain lifestyle diseases that it is considered by people in the health and fitness professions to be like medicine. And just like medicine, you need to take a specific dose to get a particular response. This is called the dose-response relationship. In other words, how much exercise you need to do to achieve specific health benefits.

This was the topic of the lecture given by endocrinologist Ralph La Forge during the World Fitness Convention held a few weeks ago in San Diego, California.

I was interested in La Forge’s lecture because people usually exhibit two kinds of extreme attitudes about exercise: “More is better” and “Tell me what the bottom line is”.

The “more is better” kind of person is the type who will take two tablets even if the instructions say to take only one. When it comes to exercise, they have the same attitude.

The “bottom line” person wants to do only the barest amount of exercise that he or she can get away with.

Both attitudes can get you into trouble. The “more is better” line of thinking can make you waste time and can also cause overuse injuries and a depressed immune system. The “bottom line” outlook can make you miss out on the health benefits of exercise if you don’t receive the right information. You may not be doing enough to reap the full value of health-related exercise.

La Forge’s lecture also tackled the type of exercise, duration and intensity needed for various health conditions. It was based on a review published in the Medicine & Science in Exercise and Sports Journal. It was a review of many scientific studies using evaluation methods of the National Institute of Health. The information that La Forge shared is by no means the final word on how much exercise you need but it is, in a nutshell, the latest that exercise science has to offer.

Aerobic exercise was the type of exercise that was used in most of the studies. “Aerobic” means walking, running, cycling, swimming, dancing – any continuous activity that rhythmically uses the arms and legs. This doesn’t mean that resistance exercise (weight lifting) or stretching don’t have any health benefits. It simply means that aerobic exercise was the method that was most studied in this particular scientific review.

Another thing pointed out by La Forge is that when it comes to health benefits, one type of aerobic activity is not better than another. With very few exceptions, it is the number of calories you burn per session, per week, and per month that seems to make the difference.

Exercise intensity
Light intensity means that you can breathe and talk normally while doing the exercise. An example would be walking around the shopping mall while talking to a friend.

Moderate intensity means that you are breathing a little harder than normal but you can still talk in short sentences before you have to catch your breath.

High intensity or vigorous exercise means that you are breathing hard and you can only say a few words at a time before catching your breath.

Health benefits
Health doesn’t have anything to do with appearance. Oftentimes, we think that being fit and healthy means having the “perfect” body or losing substantial amounts of weight. The health benefits we are talking about here have to do with internal changes like cholesterol and triglyceride levels, blood pressure, and blood sugar levels. These benefits can occur even if you don’t lose weight.

Cholesterol and triglycerides
An increase in HDL or good cholesterol and a decrease in triglycerides or fat in the bloodstream can be seen in a single exercise session. These effects last about 36 hours. That’s why even if you exercise only three times a week, you see good health results.

Forty-five minutes of moderate to high intensity exercise will do the trick in helping to raise HDL cholesterol levels.

Blood pressure
A single session of moderate intensity exercise will lower systolic blood pressure (the higher number in your blood pressure reading) by 18 to 20 mmHG and diastolic blood pressure (the lower reading) by 7 to 9 mmHg. These changes remain for 12 to 16 hours after the exercise. According to La Forge, there is no pill that will give you the same effect but this doesn’t mean you should stop taking hypertensive medication since very few people can exercise every twelve hours. In some cases, exercise and diet alone are enough to keep high blood pressure under control. In other cases, medication is necessary. Only your doctor can tell you for sure. Exercise has the greatest effect on lowering blood pressure after six months of regular workouts.

La Forge explained that there is strong evidence that low intensity exercise is also beneficial at lowering blood pressure and that exercising at high intensity levels does not appear to provide additional benefit to blood pressure reduction.

Blood clotting
Regular exercise has an anti-clotting effect similar to aspirin therapy. Research indicates that you don’t have to do much exercise to achieve this health benefit; you just have to do it regularly. It could be something as simple as walking at a low intensity for fifteen minutes daily. The wonderful news is that this anti-clotting benefit occurs even if you don’t lose weight.

However, La Forge warns that if you are on anti-coagulant medication, this doesn’t mean you should throw out your pills and do only exercise. Check with your doctor because if your blood is unusually thick, you could be at risk for a heart attack or stroke if you missed even one session of exercise.

Mortality risk reduction
Studies done on men and women of all ages found that you can reduce your risk of mortality (of all causes) by 30% with any kind of exercise (sports, gardening, weight lifting, etc) as long as you burn 1,000 calories a week doing it. Like La Forge said, when it comes to this health benefit, your body doesn’t care if you are doing “cardio hip hop” or ashtanga yoga.

You will also be happy to know that you don’t have to lose weight to reap this benefit and you can do many short exercise sessions instead of a long one. So six ten-minute sessions a day can be just as effective as one sixty-minute session.

Type 2 diabetes
One of the most significant studies published to date is the Diabetes Prevention Program of the National Institute of Health. This and other major studies have found that moderate intensity exercise that burned 700 to 1,000 calories a week reduced the risk of getting type 2 diabetes by 31% in participants with an average age of 51 years. In the over-60 age group, reduction of risk was 71%.

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