A–B
aerobic capacity The maximum amount of oxy-
gen the body can extract from ambient air (the air
of the normal environment) and use during physi-
cal activity, expressed as VO2maxin terms of milli-
liters of oxygen per kilogram of body weight per
minute (mL/kg/min). Because men have larger
LUNGS and thus greater surface area for oxygen
exchange, all other factors being equal men have
greater aerobic capacity than women. Higher
VO2maxcorrelates with increased ability to sustain
high-intensity exercise for an extended time, such
as during ENDURANCEactivities. People who partici-
pate in athletic events at a competitive level, ama-
teur or professional, typically have higher aerobic
capacity in general and a significantly higher
VO2maxin the activity of specialty such as bicy-
cling, cross-country skiing, distance running, and
swimming. Aerobic capacity is a key indicator of
cardiovascular fitness.
REPRESENTATIVE AEROBIC
CAPACITY MEASUREMENTS (VO2MAX)sedentary woman 38 milliliters per kilogram per minute
(mL/kg/min)
aerobically fit woman 60 mL/kg/min
sedentary man 42 mL/kg/min
aerobically fit man 80 mL/kg/min
Researchers believe the foundation of aerobic
capacity is genetic; some people are born with
greater aerobic capacity potential, and with sus-
tained AEROBIC EXERCISEat a competitive level they
are able to maximize that potential for high
VO2max. A sedentary (physically inactive) person
who undertakes a planned, progressive program
of aerobic exercise can often improve his or her
aerobic capacity by 20 to 30 percent. Such
improvement is significant from a health perspec-
tive because there is a strong correlation between
low aerobic capacity and increased risk for CARDIO-
VASCULAR DISEASE(CVD). Increasing aerobic capacity
consequently lowers CVD risk factors.
Direct measurement of VO2maxis fairly complex;
because of this doctors tend to conduct direct aer-
obic capacity testing only in people who have pul-
monary disease. A pulmonary function testing
center conducts direct VO2maxmeasurement, for
which the person runs on a treadmill or rides a
stationary bicycle wearing specialized equipment
that measures the exchange of oxygen and carbon
dioxide. Calculations using the measurements
determine the VO2max, usually along with other
measures that provide a detailed perspective of
lung function and lung capacity.
There are several methods for indirectly meas-
uring aerobic capacity, all of which involve per-
forming sustained aerobic exercise such as
running or walking for a determined period of
time or a known distance. Calculations use the
information to project the anticipated VO2maxfor
the data. Indirect VO2maxmeasurement is less pre-
cise than direct VO2maxmeasurement but is accu-
rate enough for most people who are engaged in
aerobic exercise and want to know, or monitor
improvements in, their aerobic capacity.
See alsoFITNESS LEVEL.aerobic exercise Physical activity that raises the
HEART RATEto 60 percent of maximum heart rate,
called the target heart rate, for a minimum contin-
uous time of 20 minutes.
A general guideline for approximating one’s
target heart rate is the “talk test.” At target heart
rate, a person should be able to speak. A person
who cannot talk during exercise is likely exceed-
ing his or her target heart rate and is working too213̇ ̇ ̇ ̇ ̇ ̇ ̇̇̇̇̇