Type and Frequency of Exercise

Not all types of exercise are equally useful for becoming physically fit.  The way in which the cardiovascular system is challenged by the exercise is all important.  Only those exercises which significantly augment the continuous flow of blood through the heart and large skeletal muscles will help cardiovascular fitness.  For example, both weight-lifting and isometrics cause the muscle being strengthened to shorten (contract or tense up).  This pressure squeezes the blood vessels, letting less blood pass instead of more.

By contrast, jogging, requiring continuous movement of the legs (and arms to some extent) results in rhythmic tensing and relaxing of muscles.  This aids the flow of blood and promotes cardiovascular fitness.

Of course, exercises which do not improve cardiovascular fitness have other benefits.  They may increase muscle strength or athletic skill – but they do not improve stamina or endurance or “wind.”  Those which improve cardiovascular fitness are rhythmic, repetitive and involve motion, and are so-called “isotonic” or dynamic.

Some exercises may enhance blood flow but still do not improve cardiovascular fitness because they cannot be kept up for a sufficiently long period of time.  Thus, the second requisite for the right kind of exercise is that it must be capable of being sustained.  It must be “aerobic.”

Aerobic exercise is the type which steadily supplies enough oxygen to the muscles for as long as the exercise is continued.  Any rhythmic, repetitive activity which can be continued for two or more minutes, without huffing and puffing afterwards, is probably aerobic.

By contrast, if enough oxygen was not being provided to the muscles, the exercise could not be continued, or if it was continued through sheer willpower, the body would immediately have to pay back the extra oxygen it borrowed from its own tissues by continuation of hard breathing after the exercise was stopped.

For example, sprinting is not aerobic.  The sprinter cannot keep going at that pace.  In comparison, the jogger, bicycle rider or swimmer seems to cover long distances effortlessly because he has attained a balance between the oxygen he needs and the oxygen he is getting though his lungs and cardiovascular system.

Dynamic, aerobic exercise must be carried out three times weekly (or more) with no more than two days elapsing between workouts or gains will be lost.