chapter
Cardiorespiratory
Fitness
5
Anaerobic and Aerobic Exercise
• To perform work, the muscles do not use the
energy released when food is broken down in
the body. Instead, the body uses food to
manufacture a substance called adenosine
triphosphate (ATP), the primary energy molecule
of the body. Only when energy is liberated from
the breakdown of ATP can the cells so the body
perform work.
• When ATP is generated by the process of using
oxygen, metabolism is aerobic. When ATP is
generated without the use of oxygen,
metabolism is anaerobic.
Anaerobic Exercise
• With anaerobic exercise, ATP is needed
quickly to perform an activity.
• Anaerobic activities do not depend on
oxygen metabolism at all because the
exercise intensity is high and the duration
is less than 2 or 3 minutes.
• Two major anaerobic energy systems:
– Immediate energy system
– Lactic acid system
Immediate Energy System
• The intermediate energy system is used
for high intensity activities that last less
than 30 seconds:
– Running the 100-meter dash
– Lifting heavy weights
• Here, the muscles use ATP and creatine
phosphate (CP) supplies that are already
stored in the muscles.
Lactic Acid System
• The lactic acid system generates ATP
for high-intensity activities lasting from
30 seconds to 3 minutes.
• In general, events or activities that require
a combination of speed and power over a
short time rely heavily on the lactic acid
energy system:
– 400-meter run
– 800-meter run
Aerobic Exercise
• Exercises are referred to as aerobic when
they depend on oxygen metabolism to
generate ATP.
• Activities must last a minimum of 3 to
5 continuous minutes to generate most
of the energy from aerobic energy
systems.
Aerobic Fitness
• Aerobic fitness is often used
interchangeably with several other terms.
– Aerobic power
– Cardiorespiratory fitness
– Cardiorespiratory endurance
– Maximal oxygen consumption
• It is the ability of the heart, blood vessels,
and the lungs to deliver oxygen to the
exercising muscles in amounts sufficient to
meet the demands of the workload.
Maximal Oxygen
Consumption
.
(VO2max)
• Maximal oxygen consumption is the
optimal capacity of the heart to pump
blood, of the lungs to fill with larger
volumes of air, and of the muscle cells to
use the oxygen and remove waste
products produced during the process of
aerobic metabolism.
• It is considered the single best indicator of
cardiorespiratory fitness.
Benefits of
Cardiorespiratory Fitness
• Enhanced ability to cope with stress
• Increased bone density and greater joint
integrity
• Enhanced body composition
• Improved blood-lipid profile
• Faster recovery from an aerobic exercise
session
• Improved submaximal exercise efficiency
• Increased
maximal oxygen consumption
.
(VO2max)
Measuring
Cardiorespiratory Fitness
• Factors such as age, gender, genetic
background,
and physical training influence
.
VO2max.
• Men tend to have a higher level of aerobic
power than women of similar ages do.
• After age 30,. sedentary individuals experience a
decrease in VO2max of about 1% per year.
• Typically, as you become older, your maximal
level of aerobic power declines.
.
VO2max
•
•
•
•
.
The VO2max, or aerobic power, of an individual
is expressed in volume (in liters) per unit of time
(in minutes).
Scores ranging from 3 to 4 liters per minute are
common for the average healthy individual who
exercises three to four times per week.
Highly
trained endurance athletes may have a
.
VO2max ranging from 5 to 6 liters per minute.
People who engage in activities such as running,
cross-country skiing,
. and cycling often have the
highest measured VO2max.
Submaximal Tests
.
Direct measurement of the VO2max is not
always practical. Instead, we recommend
using submaximal tests, or field tests, to
estimate or categorize aerobic fitness
when testing large groups or older
individuals who might be at risk.
1-mile walking test
1.5 mile-run test
12-minute run test
12-minute swimming test
Åstrand-Rhyming cycle ergometer test
Myths and Facts
• Myth—Most Americans are getting enough aerobic
exercise to reduce their risk of developing heart disease.
• Fact—More than 60% of adults do not achieve the
recommended amount of regular physical activity, and
25% of adults are not active at all.
• Myth— Younger individuals have less need to stretch
before exercising compared with older people.
• Fact— Whatever your age, being flexible helps you use
your muscles more effectively and efficiently.
• Myth—You should exercise every day to increase your
level of cardiorespiratory fitness.
• Fact—It is best to exercise on alternate days to allow
adequate time for recovery.
Sample Jogging Program
• Frequency—The optimal frequency for
jogging is every other day.
• Intensity—During the initial phase of your
program, stay in the 60 to 75% THR zone.
• Time—In the initial phase of a jogging
program, exercise for 15 to 30 minutes.
Sample Cycling Program
• Frequency—As with other forms of
cardiorespiratory exercise, you should
cycle 3 to 5 days per week.
• Intensity—Exercise at 60% of your THR
zone. Begin a cycling exercise regimen by
riding approximately 1 to 2 miles a
session, increasing to 3 to 5 miles after
several weeks.
• Time—Each cycling session should last
approximately 30 to 45 minutes.
Factors to Consider When
Selecting Activities
1. Impact (joint and body)
2. Intensity
3. Location
4. Weather
5. Social support
6. Regularity