Aerobic, or cardiovascular exercise prescription is dependent
- fitness level
- e.g.: poor, fair, average, good, excellent
- begin at a lower intensity with lower cardio fitness and
higher intensities with greater cardio fitness
- see cardiovascular fitness tests
- fitness goal(s)
- fat loss
- cardiovascular performance
- sports performance
- time constraints
- time of day
- time per day
- days available
- exercise preferences
- equipment availability
- orthopedic limitations or concerns
refers to how fast and action is performed (speed), the power
or strength required to achieve an activity (watts, level, incline),
or the effort put forth by the participant during the activity
A percentage of the maximum heart rate (HRmax), METs, or maximum
oxygen consumption (VO2max) can be used to prescribe exercise
intensity. Heart rate reserve (HRR) which takes into account
the resting heart rate can also used to prescribe exercise intensities
(See Target Heart
Exclusive use of heart rate (HR) to prescribe exercise intensity
may lead to errors in estimating relative exercise intensities
(%VO2R), particularly when the maximum heart rate is predicted
(PMHR) from age (220 - Age) instead of a direct measurement.
An age predicted prescription of 60% HRR may be as low as 70%
and as high as 80% of the actual HR max (Dishman 1994). Also
see Heart Rate Tidbits.
Intensity can also be monitored using rating of perceived
exertion (RPE). RPE is an individual's evaluation of fatigue
based on a scale from 6 to 20 or 0 to 10. Individuals who take
medications that effect heart rate can monitor exercise intensity
using RPE (ACSM 1995).
Exercise Intensity Recommendations
60 to 90%
Maximum heart rate (HR max) or Predicted HR max (PMHR)
I * direct measurement or (220 - Age)
50 to 85%
I * direct measurement
50 to 85%
I * (VO2 max / 3.5)
50 to 85%
Heart rate reserve (Karvonen formula)
I * (HR max - HR rest) + HR rest
Rating of Perceived Exertion (RPE): Original 6 to 20 scale
RPE x 10 corresponds to heart rate
RPE: Revised 0 to 10 scale
More intuitive: 4 = somewhat hard
Recently, ACSM recommended VO2 Reserve as a method to prescribe
exercise intensity. Gaskell et. al (2004) demonstrated %HRR is
better related to %VO2max than to VO2R in 630 initially sedentary
individuals (ages 17 to 65 years). Gaskell concludes %VO2max
is the better measure for prescribing exercise intensity.
Maximal aerobic capacity can calculated using various aerobic
fitness tests including, 1
Mile Walk, YMCA Cycle
Treadmill, 1.5 Mile
Run, 12 Minute Run.
An exercise intensity can be prescribed using percent range of
VO2 max or METs: Treadmill,
Percent Max Heart Rate
Percent VO2 max
Exercise adherence may decrease if exercise intensity is too
high, particularly the first 4 to 6 weeks (ACSM 1995). Intensity
should increase in a gradual and systematic manner as physiological
adaptation occurs. Ultimately the appropriate exercise intensity
is safe, tolerable, and achieves the desired caloric output within
the time constraints of the exercise session (ACSM 1995).
The ACSM recommends 20 to 60 minutes of continuous aerobic
activity. Time constrains of the individual must be considered.
Depending upon individual fitness goals exercise sessions may
be of moderate duration (20 to 30 minutes) excluding time spent
warming up and cooling down. Initial programs may last 12 to
15 minutes and progress toward 20 minutes. Severely deconditioned
individuals may need to perform multiple sessions of short duration
(~10 minutes). Duration should increase as adaptation to training
occurs without evidence of undue fatigue or injury (ACSM 1995).
Scheduling constrains of the individual must be considered.
The American College of Sports Medicine recommends aerobic activity
to be performed 3 to 5 session times a week. It is recommended
that individuals beginning an exercise program should perform
aerobic exercise 3 days per week on non-consecutive days. Severely
deconditioned individual may need to perform multiple sessions
of short duration (~10 minutes) (ACSM 1995). Individuals just
beginning weight-bearing exercise (eg: jogging, aerobic dance,
etc.) may be advised to wait 48 hours between bouts to prevent
overuse injuries. If exercising on consecutive days, alternating
between two modes of exercise (e.g.: walking one day, cycling
next day) can be suggested, particularly for those who are overweight
or those who have had certain orthopedic injuries in the past.
The volume refers to the sum work performed in a given training
phase. It includes the duration of the activity, the distance,
and the number of times a bout was performed within a training
period (E.g.: 40 km per week).
Activities that involve large muscle
groups over prolonged periods of time offer the greatest improvement
in VO2 max. These activities are rhythmic and aerobic in nature
(e.g. walking, running, hiking, stair climbing, swimming cycling,
rowing, dancing, skating, cross country skiing, rope jumping,
etc.). An individual's skill and enjoyment of an activity are
factors that will influence compliance and ultimately the desired
outcomes (ACSM 1995).
The type of exercise chosen should be enjoyable. The risk
of injury from high-impact activities must be weighed when choosing
exercise modalities, particularly for novice or overweight individual.
A variety of different exercises may be desirable to reduce repetitive
orthopedic stresses (ACSM 1995).
Classification of Cardiovascular Exercises (ACSM 1995)
- Energy expenditure is relatively low and can be readily maintained
at a constant intensity
- e.g. walking, cycling
- more precise control of exercise intensity
- ideal for deconditioned individuals
- Energy expenditure is dependent upon skill
- e.g. swimming, cross country skiing, skating, aerobic dance,
and aerobic step exercises
- can provide constant intensity if skill is adequate
- may be used in early stages of conditioning if fitness is
- Intensity and skill is highly variable
- e.g. racquet sports, basketball, soccer
- provides variety and group interaction
- carefully considered for high risk or low-fit individuals
- competitive factors must be considered and minimized
Specificity & Cross Training
Training effects are specific to the muscle groups used during
training and the type of training program implemented (Fox, McKenzie,
Cycling training improved VO2 max more when tested on the
cycle than when tested on the treadmill. The training effects
of running are more general than cycling training. Running improved
VO2 max approximately the same extent whether measured on the
cycle or treadmill (Pechar et. al., 1974)
American College of Sports Medicine, (1995) Principles
of Exercise Prescription, William & Wilkins, 5.
Dishman RK (1994). Prescribing exercise intensity for healthy
adults using perceived exertion. Medicine & Science in Sports
& Exercise. 26: 1087-1094.
Fox E, McKenzie D, Cohen K. (1975). Specificity of training:
metabolic and circulatory responses. Med Sci Sports, 7(1):83.
Pechar G., McArdle W., Katch F., Magel J., DeLuca J. (1974).
Specificity of cardiorespiratory adaptation to bicycle and treadmill
training. J. Appl Physiology. 36(6):753-756.