In the column which I wrote for the week of February 10th, I commented at length on the importance of exercising at a certain level of exertion if a person wanted to improve his or her physical fitness level. I had written that column as part of a series on the whole question of ordinary people, those who do not define themselves as athletes, who have decided to improve their health. The basis for the whole series is that fitness is attainable by just about everyone and that the same concepts, modified as need be, which work for athletes apply to the rest of us as well.

    I interrupted that series in my last two efforts because I did want to comment on the then imminent opening of the Canada Winter Games here on my home turf in northern New Brunswick and on their progression through the first week of competition. I want to return to that series now perhaps with the thought that some of us may have been inspired by the Games themselves , and by the hints of spring in the air - to start to get our bodies back into some semblance of physical fitness.

    First I have a couple of reminders: It is possible to exercise three or four times a week for fifteen or twenty minutes a time and, by so doing, maintain a current level of fitness, but, if you want to improve on your current level you will have to do more than that. It is essential to accept that fitness begins with your heart and lungs and not your muscular strength. To improve heart and lung (cardiovascular - or aerobic) conditioning, it is necessary to get out and move around vigorously enough to push your heart rate up into what we call a Training Heart Rate. In the column of February 10th I offered a formula for determining that THR (220-your age x 3/4 +/-20 beats) and tried to emphasize that it was necessary to exercise within that range in order to benefit from the work. (15)

    I try to emphasize to coaches, to my own athletes and to anyone else who wants to listen that an informed person is one who will more likely want to do the work required to achieve any goal. I am following that principle here by explaining in more detail just how and why cardiovascular fitness is important. So, please bear with me.

    When we exercise within the THR zone, we force our lungs to take in supplies of oxygen which are greater that normal. We also force our hearts to beat faster which pumps that oxygen, via our blood, to our muscles. Our muscles use that oxygen to break down stored fats which they can then burn for energy. The oxygen also combines with the lactic acid which the muscles provide as a by-product of their work and breaks it down into useful, or at least harmless, substances. (Lactic acid is the stuff which produces muscle stiffness and fatigue). It follow then that the more oxygen we can inhale with each breath we take, the more there is in the blood stream for the muscles to use. Strong lungs can handle larger volumes of oxygen to supply the heart; a stronger heart can transport more of that oxygen-enriched blood to the muscles with each stroke. The more such blood to reach the muscle fibres, the more they can produce energy and the better they can reduce lactic acid to useful glycogens.

    It is critical here to realize that this process only takes place when your hears is working with that THR. At lower rates the process doesn't kick in (except over periods of several hours or longer) and at higher rates, the whole cardiovascular system begins to perform in another way. That is why even very highly conditioned athletes continue to do seventy-five or eighty percent of their total training within their THR zone. It is somewhat paradoxical then, at least at first glance, for people to realize that ideal fitness programs emphasize the absolute need for moderate forms of exercise over extended periods of time rather than extreme forms for shorter periods.

More next time.