ciency, flexible joints, and healthyBODY MASS INDEX
(BMI). Regular physical activity during childhood
appears to further reduce risk factors for numer-
ous health conditions in adulthood, even when
activity eases. Children for whom daily exercise is
a part of lifestyle are far more inclined to maintain
physical activity as a priority in adulthood.
See also EXERCISE AND HEALTH; HEALTHYPEOPLE
2010 ; METABOLIC EQUIVALENT (MET); NUTRITIONAL
NEEDS; WALKING FOR FITNESS.
protein loading The practice of consuming
increased quantities of protein, such as in meats,
for a period of time before an athletic event. Some
athletes who participate in activities that require
MUSCLE STRENGTHeat high amounts of protein to
help build muscle mass. Though the body requires
amino acids, which it acquires from dietary pro-
teins, to repair and maintain tissues of all kinds
throughout the body, including muscle tissue, a
typical diet that contains about 15 percent protein
generally meets the body’s protein needs.
Excessive quantities of protein consumed in the
diet, like excesses of dietary fats and carbohy-
drates, eventually becomes first GLUCOSEand then
glycogen (short-term energy storage) and fat
(long-term energy storage). Some studies suggest
that long-term excessive protein consumption
(usually of protein supplements) can strain the fil-
tering mechanism of the KIDNEYS and can cause
kidney damage. However, these findings are
inconclusive, particularly in people who have nor-
mal kidney function and have no significant
health conditions.
Nutrition and fitness experts recommend eating
a meal that contains primarily carbohydrates and
protein about two hours after intense exercise or a
competitive event to help the body more quickly
replenish the stores of glucose and amino acids it
drew on during the physical activity. Most health
experts do not recommend protein loading before
an event or a competition, and recommend pro-
tein supplements only for people who cannot
obtain adequate dietary protein because of health
conditions.
See also CARBOHYDRATE LOADING; DIET AND HEALTH;
NUTRIENTS; NUTRITIONAL NEEDS; NUTRITIONAL SUPPLE-
MENTS.
resistance exercise Physical activity, also called
resistance TRAINING, in which the muscles exert
effort against pressure, such as lifting weights.
Resistance exercise, often called weight training
when it involves the use of weights, enlarges and
strengthens muscles and decreases body fat. It also
improves the ability of the bones to retain cal-
cium, maintaining BONE DENSITY and STRENGTH.
Resistance exercise is particularly important for
women over the age of 50, as BONEloss that can
lead to OSTEOPOROSISbecomes a significant concern
after MENOPAUSE. Health and fitness experts recom-
mend resistance exercise two or three days a
week, alternating with AEROBIC EXERCISEfor a com-
prehensive fitness program.BIG MUSCLES
Some people desire and other people dread the
prospect of bulky muscles. Conventional resist-
ance exercise is more likely to disappoint the for-
mer and please the latter. Though resistance
exercise decreases the number of fat cells in
MUSCLEtissue to give the muscles firmness and
definition, it does not generate monster muscles.A methodical approach exercise physiologists
call progressive overload is the key to effective
resistance training. Progressive overload is the
practice of periodically increasing the difficulty of
resistance as MUSCLEgroups develop strength and
become accustomed to the established resistance
level. Most people should increase resistance
every six to eight resistance exercise sessions, or
about every two weeks. When working with
weights, progressive overload can take place by
increasing the amount of weight (intensity), the
number of repetitions (duration), or the number
of sessions (frequency). Many people combine
these approaches. Resistance bands, another pop-
ular method of resistance exercise, come in differ-
ent resistance levels, though generally the same
concepts of progressive overload apply.
Each resistance exercise session should include
multiple sets with rest periods of one to two min-
utes between each set. Rest, which allows the
muscles to recover and “learn” the exercise (mus-
cle memory), is a crucial component of a resist-
ance exercise program. For most people, 20 to 40resistance exercise 229