ISO METRICS VERSUS ISOTONICS
For some years, the virtues of isometrics have been
trumpeted, often in advertising which promises an isometric system that
"will put you in top shape in a minute a day-and no sweat."
Isometrics involve muscular contractions without movement. The sys- tem is
based on the principle that when a muscle is required to work beyond its usual
intensity, it will grow. In isometrics, one set of muscles may be pitted
against another or against an immovable object such as a doorway or floor.
Put
your palms together and push your hands against each other as hard as you can,
without moving either hand. Or push against a closed door which does not move.
These are isometrics. On the other hand, isotonic involve movement. Running,
lifting, push-ups, sit-ups, virtually all sports are isotonic. Isometric
exercises can be useful-for example, in correcting specific deficiencies such
as building arm muscles or putting back into condition a leg that has been in a
cast.
They may be useful, too, as a supplement to isotonic for
further development of specific major muscles and muscle areas. But it is
important to realize that your objective in exercising is not simply to build
muscular strength. Strength is the ability to work against a resistance.
Additionally, you need muscular endurance, the ability of a muscle to respond
repetitively for a relatively long period of time; flexibility or muscular elasticity
so you can use the muscle effectively throughout its whole range of motion; and
cardiovascular-pulmonary efficiency-the adaptive response of heart, blood
vessels; and lungs to work and exercise.
Isometrics can help develop strength.
But for the other needs, you have to get down on the floor and do push-ups and
sit-ups and other isotonic exercise; you have to walk and jog or swim; you have
to work the muscles through their whole range and work them repeatedly; and you
have to sweat at the job and give the heart and blood vessels and lungs a
workout. There is no shortcut.
