The fluctuations of the 23-day physical cycle are thought to influence man's strength, endurance, energy, and general physical well-being. We're all aware that our energy levels vary. Some mornings we can scarcely pull ourselves out of bed; others, though we don't quite wake up somersaulting, we are ready to go even before taking a cup of coffee. The biorhythm theory suggests that we can calculate days we might be more likely to zip through and days when we'll drag along.
Let's use the sample physical curve below to become acquainted with the theory. During the first half of the 23-day cycle (11,5 days), one's physical well-being is increasing. This portion of the cycle is sometimes referred to as a "discharge period," analogous to the time when a battery is discharging electrical power, using up its stored energy. During this first half of the cycle, a person is quite vigorous and appears to command a powerful source of energy.
The second half of the 23-day cycle (also 11,5 days) is a time of reduced vigor, recuperation, and storage of new energy, as when a battery is recharging. These are the days when the curve on the chart is below the base line. To an athlete, this is the time when he is in a slump, and the stay-at home experiences his own kind of slump as well. During this time, man is more content to rest and regain his strength. That's not to say that work, tennis, and spring cleaning simply cease every other 11 days, but the drive slows down, the time-outs become a little more frequent, a good book and a catnap begin to look more attractive. Doctors who follow the theory find this time ideal for a patient's recuperation or therapy.
It is important to emphasize that the curve does not divide into a "good" half and a "bad" half. Neither portion is necessarily better or worse than the other-fortunately, since each adds up to half a lifetime! The theory of biorhythms aims to alert you to your capacities and potentials, the days when your basic drives (in this case physical) are at high, low, or critical tide. A low period is no more evil than a low gas tank in your car. If you read the gauge properly, you won't plan to drive 500 miles that day. You'll add more fuel-for the human machine, this means a little rest, a little bit of being good to yourself. A low period that is observed and used wisely can nourish the body. An athlete, for instance, might adjust his training schedule to provide for more rest or less intense concentration during the second half of his cycle.
Properly used, a low period can give the same benefit as sleep to an exhausted man. A high day may not be an unadulterated blessing, either. Although more can be accomplished in the first half of the cycle, the physical plant can be tuned so high that a man might over-exert or try to go beyond his physical potential, ending up with a pulled muscle on the fifteenth hole of the golf course. A lot depends on individual condition. Professional athletes have often hit home runs, caught long passes, and broken records at the peak of their physical cycles.
There are two "critical" or "cautionary" days in every complete 23-day physical cycle. These are the first day, when each new cycle begins, and the halfway mark, between the 11th and 12th days, when energy switches into the recharge period. The body is relatively unstable and less resistant to stress on these days; heart attacks, for example,
apparently tend to fall on critical days of this curve. Again, it is important to note that the days in themselves are not critical. The person's condition on that day may bear watching; he might react badly to strain imposed by the outside world or by his own body. There is no magical hex or voodoo spell that will make a heart fail at the "critical" or "cautionary" point of the physical cycle, but a man who has recently had a heart attack might take extra precautions on such a day. A taxi driver might be extra careful too. Or someone working in a machine shop. Or someone shepherding fifteen pre-school children out to the playground.