Preventive Medicine Column
August 10, 2008
The Olympics are under way, and all thoughts turn to exercise. Well, at least to watching other people get some!
The health benefits of regular physical activity are legion. Routine exercise is associated with a reduced risk of heart disease, cancer, diabetes, stroke, high blood pressure, and even infection. Mountains of research evidence make it clear that exercise can both add years to life, and life to years. In the Diabetes Prevention Program, habitual, moderate physical activity was part of a simple lifestyle formula that slashed the occurrence of diabetes in high-risk individuals by nearly 60%.
Exercise is important in almost any successful weight loss effort, and even more important in maintaining weight loss for the long haul. In the National Weight Control Registry, our best source of information about long term maintenance of weight loss, everyone is physically active.
But exercise, and the fitness that results from it, protect against many of the adverse effects of obesity independently of effects on weight. This has resulted in one of the more persistent and contentious debates in the obesity field: the relative importance of fitness versus fatness.
Some proponents of the benefits of physical activity have argued that being fit is good for health no matter what one weighs. Fitness, they say, trumps fatness when it comes to health benefits.
The reality, however, is much more congruent with common sense. Most people who exercise routinely enough to be fit are thinner than most people who don’t. In the real world, those people who manage to be thin but not at all fit are rather rare, and often are both thin and unfit because of health problems. Those who manage to be fit without winding up at least relatively thin are even rarer.
Studies at the Harvard School of Public Health have shown that both fitness and fatness matter with regard to key health outcomes. As one would predict, lean and fit is associated with the best outcomes of all; followed by fit but not lean, then lean but not fit, and finally, neither lean nor fit. The first and last of these groups tend to be far more populous than the middle two because fitness and unfatness go together, as do fatness and unfitness.
The powerful benefits of physical activity do not come free of risk. Physical exertion that protects us from heart disease can also be the precipitant of a heart attack. A brief exploration of what happens to the body, and the heart, during exercise resolves this apparent paradox.
Working muscles need extra fuel, and in particular, extra oxygen. To deliver these, respiratory rate and chest excursion both increase, ramping up oxygen delivery to the blood by three-fold or more. Delivery of that oxygen to cells increases with the volume and frequency of heart beats, known as cardiac output. This can increase by more than four-fold.
But the heart itself is a working muscle, and it, too, needs more oxygen when its work increases. The heart can only deliver oxygen to itself when heart muscle is relaxed, the span between heart beats known as diastole. See the problem? As heart rate goes up, the time between beats quickly dwindles. The heart has less and less time to get oxygen to itself just when its oxygen requirements are rising! The poets were more right than they knew in choosing the heart as a symbol of courage, honor, and selfless devotion.
When the coronary arteries that supply the heart are healthy and unobstructed, the heart can get enough oxygen during even extreme exertion. Not so if those arteries are partly occluded by atherosclerotic plaque. Reduced blood flow can lead to a painful deficit of oxygen, known as angina. If the increased force of blood flow causes the plaque to rupture, a heart attack ensues. So while exercise is vital to good health, being healthy is important for a body to tolerate the stresses of exercise. This is why those at risk of heart disease should confer with their doctor before starting any exercise.
In the case of Olympic athletes, the stresses of exercise are extreme and not necessarily optimal for health. Extremes of exertion are an obvious risk for injury, but also suppress the immune system, increasing the risk for infections, and perhaps even cancer over time. The powerful effects of extreme exertion on the body are on display in the varied physiques of the athletes; exercise literally sculpts the bodies of swimmers to all look like swimmers, gymnasts to look like gymnasts, and so on.
The recent trend in physical activity research has been to demonstrate how routine daily activity can confer health benefits. In other words, we don’t need to make the Olympic team for physical activity to be a major factor in our life, and our health. Moderate activity for at least 30 minutes over the course of most days will do the trick.
So enjoy the spectacle of the Olympics from your favorite perch. But honor the spirit of the Games- and get off the couch from time to time.
Dr. David L. Katz; www.davidkatzmd.com The Squat Form:
• Begin by standing with your feet slightly wider then shoulder width apart. Extend the arms out so they are parallel to the ground. As you squat down extend the hips and buttocks towards the wall behind you, without the knees over extending the toes. Maintaining a tight core and a slight inward curve of the lower back. The feet should be firmly planted on the ground with the emphasis of body weight being on the heels. While maintaining good posture retracting the shoulders by squeezing the shoulder blades together. As well as keeping the head in a neutral position. At the end of the movement the thighs should be parallel to the ground. To rise to the standing position drive the heels into the ground focusing on using the glutes.
High Rise Pack
• Once the body weight squat becomes easy, resistance is needed. In the firehouse you can utilize a high rise pack for resistance. Place the high rise pack over your shoulders, equalizing the weight distribution. Perform the squat movement as described above. High Rise Pack Left/Right Shoulder
• To increase the resistance and trunk stabilization, place the high rise pack over the left shoulder and perform the squat movement as described above for 5 repetitions. Then switch the high rise pack over to the right shoulder and perform 5 more repetitions. Maintaining strong core stabilization so the hips and shoulders stay square to the wall in front of you.
This can also be performed with a rolled hose pack.
Before starting any new exercise program you should check with your medical doctor to make sure the exercise is safe for you to perform. If at anytime you experience any pain or discomfort while performing an exercise you should stop the exercise and not resume untill properly instructed by a training professional.