ime at which it is taken. Those who are in perfect
health may engage in it at almost any hour except immediately after a
meal; but those who are not robust ought to confine their hours of
exercise within narrower limits. To a person in full vigor, a good walk,
or other brisk exercise before breakfast may be highly beneficial and
exhilarating, while to an invalid or delicate person it will be likely
to prove detrimental. In order to prove beneficial, exercise must be
resorted to only when the system is sufficiently vigorous to be able to
meet it. This is usually the case after a lapse of from two to four
hours after a moderate meal. The forenoon, then, will generally be found
the best time for exercise for persons whose habits are sedentary. If
exercise be delayed till the system feels exhaustion from want of food,
its tendency will be to dissipate the strength that remains and impair
digestion; while, if taken at the proper time, it will invigorate the
system and promote digestion. The reasons are obvious; for exercise of
every kind causes increased action and waste in the organ, and if there
be not materials and vigor enough in the system to keep up that action
and supply the waste, nothing but increased debility can reasonably be
expected.

Active exercise immediately _before_ meals is injurious. The reasons are
apparent, for muscular exercise directs a flow of blood and nervous
energy to the surface and extremities; and it is an established law in
physiology, that energetic action can not be kept up in two distant
parts of the system at the same time. Hence, whenever a meal is taken
immediately after vigorous exercise, the stomach is taken at
disadvantage, and, from want of the necessary action in its vessels and
nerves, is unable to carry on digestion with success. This is very
obviously the case where the exercise has been severe or protracted.

Active exercise ought to be equally avoided immediately _after_ a heavy
meal, for then the functions of the digestive organs are in the highest
state of activity. If the muscular system be called into vigorous action
under such circumstances, it will cause a withdrawal of the vital
stimuli of the blood and nervous influence from the stomach to the
extremities, which can not fail greatly to retard the digestive process.
In accordance with this well-established fact, there is a natural and
marked aversion to active pursuits after a full meal. A mere stroll,
which requires no