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Does Exercise Really Keep Us Healthy?


Fortunately, for the most part, Gina Kolatas’ article, “Does Exercise Really Keep Us Healthy?” in the Health Section of The New York Times agrees with the associated health benefits of exercise. However, I am going to focus on specific areas where the article casts a shadow of doubt upon some of the benefits of exercise.

“While exercise can boost mood, its health benefits have been oversold.”

Two thirds of the US population is overweight or obese. Half of these are obese. The World Health Organization Fact Sheet on Overweight and Obesity cites a sedentary lifestyle as a major contributor to excess weight. Since these conditions lead to an increase risk of coronary artery disease, type 2 diabetes and some cancers, it makes sense that physical activity helps decrease these risks.

Though the evidence is mixed, exercise may also provide benefits for people with osteoporosis.

The evidence showing positive effects for weight bearing exercise on maintaining bone health is overwhelming. Studies show that strength training shows significant gains in bone density, especially in older male and female adults. Where the evidence “is mixed,” is exactly what volume, intensity, and exercise are most effective at helping to prevent osteoporosis. The American College of Sports Medicine’s Position Stand on Osteoporosis and Exercise supports the benefits of strength training on bone health.

For better health, simply walk for 20 or 30 minutes a day, boosters say…

Any increase in activity helps with a calorie deficit and this recommendation may be a good starting point for people with weight issues who do not have the cardiovascular capacity to exercise for longer periods. The point is to start out in manageable steps and build endurance and intensity as you get stronger. This type of regimen also helps with exercise adherence which is necessary for the consistency necessary for results.

Despite trying hard, those who dieted and worked out lost very little weight.

The recommended amount of weight loss is 1-2 lbs per week. There are no details of the Federal study so we do not know the length of the program, the precondition of the subjects, duration or exercise intensity of the diet and exercise group who “lost very little weight.” With respect to the weight loss, we do not know whether the loss is relative or in absolute terms.

Lifting weights builds muscles but will not make you burn more calories.

Building muscle will help burn more calories at rest. Muscle mass is related to BMR (Basal Metabolic Rate.) Muscle tissue has a high energy requirement. Sarcopenia (loss of muscle) is a reason for weight gain as we age. Our BMR decreases because we do not have the same energy requirements as when we were younger with more muscle mass. According to the American Council on Exercise personal training manual, muscle loss in non-training adults leads to a 5% reduction in BMR for every decade of life. We also lose a half pound of muscle every year after the age of 25 if we remain sedentary. Studies have shown that regular resistance training can stem weight gain associated with sarcopenia and even reversed the process. The bottom line is the old adage, if you don’t use it, you will lose it.

Jack Wilmore, an exercise physiologist at Texas A & M University, calculated that the average amount of muscle that men gained after a serious 12-week weight-lifting program was 2 kilograms, or 4.4 pounds. That added muscle would increase the metabolic rate by only 24 calories a day.

Increasing your BMR by 24 calories per day is equal to approximately 672 calories per month. That is the equivalent of running for approximately an hour. Twelve weeks of training is a relatively short period since the first six weeks of a beginning strength program tends to be low in volume (Low weight and high number of repetitions of between 12-20 repetitions) and focuses on muscular endurance. It is mostly neuromuscular learning and not hypertrophy that accounts for strength gains during this phase. There are no details of the subjects such as experience and exercise prescription.

…it is impossible to know with confidence whether exercise prevents heart disease or whether people who are less likely to get heart disease are also more likely to be exercising.

Cardiovascular exercise is any activity that challenges the cardiovascular and respiratory systems. This type of exercise helps reduce the risk of heart disease. Cardiac muscle responds in the same way as skeletal muscle to exercise by getting stronger. One of the many chronic adaptations to cardiovascular exercise is an increase in stroke volume because the heart chambers can increase in size by 40%. Studies show that cross-sectional area of coronary arteries increases in proportion to ventricular size increases. Stroke volume is the amount of blood pumped from the left ventricle in one heartbeat. Since the heart is pumping more blood in a minute (cardiac output), than the heart has to beat less times in a minute at rest. A lower resting heart rate is a good measure of level of fitness as well as how quickly the heart recovers from exercise. Resting heart rate refers to the number of heart beats per minute (bpm.) Just like skeletal muscle, if cardiac muscle is stretched regularly, it will have greater contractibility. Cardiovascular exercise also increases HDL (good cholesterol) levels in the blood. HDL helps remove LDL “bad”cholesterol from the blood and also helps reduce body fat which would otherwise coat artery walls and eventually form plaque. The American College of Sports Medicine considers low levels of HDL in the blood a coronary artery disease (CAD) risk factor.