Really, what is the final word on the role of exercising and physical activity in supporting health? Aren't fitness and health two sides of the same coin, both contributing to longevity?

All depends. There is a certain ambiguity about physical activity as a health factor. By far the oldest - and the only one - scientifically proven method to significantly prolong life is to restrict caloric intake. Mice at 35% of what is their ad lib (free feeding) caloric intake, have some 50% longer life-span. Similar effect is observed in a number of other critters, from insects to monkeys. Chances are, we humans are no exception.

Obviously, lower caloric intake requires appropriately reduced physical activity as well. Body burns less and slower, and lasts longer. This is not to take away from the good sides of exercising. Benefits of exercising are many: from strengthening the muscle tissue and improving posture, to stimulating metabolism, lymphatic system and elimination, to strengthening cardiovascular and respiratory system, bringing richer blood flow to tissues and cells, and so on. Exercise-induced sweating can greatly help detoxication, and running exercises will also increase your bone density.

Needless to say, all this does strengthen body's resistance to a host of modern diseases, including cancer. Very important benefit of exercising is stress relief.

Also, recent studies indicate another long-term benefit of exercising: it is good for your brain. The same scientist that, decade ago, discovered that brain in adult mice does continue to regenerate and produce new neural cells, has found that exercising substantially increases cerebral blood volume - a clear indicator of more blood vessels, and more cells in the brain - in human participants, in as little as 12 weeks (Gage, Small, Sloan, Columbia University, spring 2007). It includes increased brain volume in regions associated with age-related decline in both structure and cognition.

Not surprisingly, other recent studies - including the 35-year study at the Karolinska Institute in Stockholm - have found out that those who exercise have significantly lower rate of dementia and Alzheimer's.

But maximizing your life-span

doesn't necessarily imply best overall physical condition,

in terms of physical abilities and endurance.

Obviously, reduced physical activity imposed by the minimized caloric intake, will result in not only loss of body fat reserves, but also significant loss of the muscle mass and, with time, bone mass as well. There are also some other potentially worrying consequences, listed on the CR (Calorie Restriction) Society web site.

However, good part of these seemingly negative results of the caloric dietary reduction is simply the mother nature's wisdom. Balancing act, if you will. For instance, with lighter body, you don't need as much of a muscle mass, nor as strong and massive bones. Thus, the loss of bone mass under these circumstance is actually an act of optimizing the body structure, and doesn't necessarily equal increased bone fracture risk.

And, if you are still concerned about bone mass loss, there are very efficient low-calorie exercises to maintain bone mass, such as a few minutes a day of trampoline hopping (which stimulates rebuild of the inner bone structure - so called trabecular bone), or simply standing on a whole body vibration platform for 10-15 minutes a day, which in effect simulates regular vibration of an active muscle and fools the bone into rebuilding.

As usual, extremes are undesirable in either direction. Too low caloric intake would require you to sacrifice some things in your life that you may not like to. On the other hand, pumping up your caloric intake just in order to keep up with an extensive level of exercise will likely take a toll on your body, and ultimately

shorten your life.

Last year (2006), there were at least six heart-related deaths in US marathons. Direct studies of marathon runners at the 2006 Boston marathon indicated that their hearts may be stressed beyond acceptable level (and so are certainly their joints and bones).

Of course, the marathon is extremely physically demanding, but what matters is not so much the level of intensity, as it is how well prepared for it is the body. It was almost invariably those marathon runners with relatively low preparation level that suffered most of ill effects.

Likewise, you can hurt your body by doing just about any physical activity for which it isn't adequately prepared for, or is too demanding for your overall health level. Choose your exercise type and intensity based on your exercise goal, and make sure you are not doing too much too soon. There are much more important things in life to build than body muscles; make your exercise what it is supposed to be: a healthful, enjoyable activity you'll be looking forward to.

There are many forms of exercise to choose from - walking, dancing, stretching, jogging, calisthenics, isometrics, weight lifting, team sports - you name it. The main rule is: in order to make it effective, it needs to be done on a regular basis. R

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