Physical Fitness Evaluation

Abstract

Physical fitness is simply defined as the capacity to perform physical work. Energy is necessary to perform work and sustain life and is extracted aerobically and anaerobically. Evaluation of aerobic fitness is based on the assessment of maximal oxygen consumption (Vo2 max), either directly or indirectly. Direct assessment of Vo2 max is usually determined by a graded exercise test using open circuit spirometry. Indirect assessments of Vo2 max use standardized exercise protocols. Such protocols can also be used to estimate Vo2 max with the subject exercising at submaximal heart rate levels. These estimates are based on the linear relationship between exercise heart rate and O2 consumption. Walking and step tests that allow an estimate of fitness based on exercise and recovery heart rate responses are also available. Evaluation of anaerobic power consists of 30 to 120 seconds of high-intensity effort on a cycle ergometer, known as the Wingate test. Muscular strength is assessed by a maximum effort against the greatest resistance one can move through the full range of motion once, known as the 1-repetition maximum. Muscular endurance is assessed by tests requiring more than 12 repetitions, or the maximum number of push-ups or sit-ups one can execute without rest.

Full text

http://ajl.sagepub.com/
American Journal of Lifestyle Medicine
http://ajl.sagepub.com/content/early/2014/01/16/1559827613520128
The online version of this article can be found at:
DOI: 10.1177/1559827613520128
published online 20 January 2014AMERICAN JOURNAL OF LIFESTYLE MEDICINE
Peter Kokkinos
Physical Fitness Evaluation
Published by:
http://www.sagepublications.com
can be found at:American Journal of Lifestyle MedicineAdditional services and information for
http://ajl.sagepub.com/cgi/alertsEmail Alerts:
http://ajl.sagepub.com/subscriptionsSubscriptions:
http://www.sagepub.com/journalsReprints.navReprints:
http://www.sagepub.com/journalsPermissions.navPermissions:
What is This?
- Jan 20, 2014OnlineFirst Version of Record >>
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

1
vol. XX • no X American Journal of Lifestyle Medicine
Peter Kokkinos, PhD
Abstract: Physical fitness is simply
defined as the capacity to perform
physical work. Energy is necessary
to perform work and sustain life
and is extracted aerobically and
anaerobically. Evaluation of aerobic
fitness is based on the assessment of
maximal oxygen consumption (Vo2
max), either directly or indirectly.
Direct assessment of Vo2 max is usually
determined by a graded exercise
test using open circuit spirometry.
Indirect assessments of Vo2 max use
standardized exercise protocols. Such
protocols can also be used to estimate
Vo2 max with the subject exercising at
submaximal heart rate levels. These
estimates are based on the linear
relationship between exercise heart
rate and O2 consumption. Walking
and step tests that allow an estimate of
fitness based on exercise and recovery
heart rate responses are also available.
Evaluation of anaerobic power consists
of 30 to 120 seconds of high-intensity
effort on a cycle ergometer, known as
the Wingate test. Muscular strength is
assessed by a maximum effort against
the greatest resistance one can move
through the full range of motion once,
known as the 1-repetition maximum.
Muscular endurance is assessed by tests
requiring more than 12 repetitions, or
the maximum number of push-ups or
sit-ups one can execute without rest.
Keywords: physical activity; fitness;
exercise; evaluations
Introduction
Work is defined as the energy transfer
or force required to move an object at a
certain distance. For humans, the energy
necessary for locomotion or the
displacement of an object (work)
requires muscular involvement. Thus, the
capacity to perform such physical tasks
is defined as physical fitness.
Unlike machines, energy transfer
(work) in humans is difficult to assess
precisely. Energy for work is derived
mainly from 2 systems (aerobic and
anaerobic) working synergistically to
perform a given task that is usually more
complex than moving an object from
point A to point B. For example, the
complex movements involved in sports
such as change in direction requires
more energy than moving linearly.
Isometric contractions such as those
involving certain stances in gymnastics
(iron cross, parallel bars) demand
tremendous amounts of energy.
However, movement in such tasks is
absent and therefore (theoretically) work
is not performed. Accordingly, the
precise assessment of work and physical
fitness is subject to these limitations.
Definition of Physical
Activity, Exercise,
and Fitness
Physical Activity and Exercise
Physical activity and exercise both
describe a physiologic state that requires
a degree of muscular effort beyond
resting conditions. Although the terms
can be used interchangeably in some
instances, there are differences. Physical
activity is defined as movement that
requires any form of skeletal muscle
contraction and results in energy
expenditure beyond resting levels.1,2 This
work can be performed as part of the
daily requirements of the job or around
the house (yard work), or leisure time
activities also known as recreational
activities. Accurate assessment of the
level of physical activity in large
520128AJLXXX10.1177/1559827613520128American Journal of Lifestyle Medicine / MONTH MONTH XXXXvol. XX no. X / American Journal of Lifestyle Medicine
research-articleXXXX
Physical Fitness Evaluation
Accurate assessment of the level of
physical activity in large populations
becomes important when investigating
associations between health benefits
and a physically active lifestyle.
DOI: 10.1177/1559827613520128. Manuscript received October 17, 2013; accepted November 12, 2013. From Cardiology Division, Veterans Affairs Medical Center;
Georgetown University School of Medicine; and George Washington University School of Medicine and Health Sciences, Washington, DC. Address correspondence to Peter
Kokkinos, PhD, Cardiology Division, Veterans Affairs Medical Center, 50 Irving Street NW, Washington, DC 20422; e-mail: peter.kokkinos@va.gov.
For reprints and permissions queries, please visit SAGE’s Web site at http://www.sagepub.com/journalsPermissions.nav.
Copyright © 2014 The Author(s)
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

2
Mon • Mon XXXXAmerican Journal of Lifestyle Medicine
populations becomes important when
investigating associations between health
benefits and a physically active lifestyle.
Exercise is best defined as a structured
program designed to achieve a state of
physical exertion of certain intensity,
duration, and frequency.2 The by-product
of exercise intensity and duration yields
the volume of work or energy
expenditure per unit of time. Exercise
programs can be tailored to one
individual. Furthermore, the intensity,
duration, and frequency can be
manipulated to produce the desired goals.
For these reasons, exercise programs are
implemented in interventional research
studies to assess the effects of exercise on
a specific physiologic parameter, such as
blood pressure, body weight, blood lipid,
and so on.
Physical Fitness
Physical fitness is defined as a set of
physical attributes that people have or
achieve that relates to the ability to
perform physical activity.1,2 These
attributes have important implications,
including one’s ability to perform
recreational or occupational activities, the
determination of disability, injury
prevention, and skeletal muscle, bone,
and cardiovascular health. Moreover,
higher fitness is strongly associated with
better long-term health outcomes.3,4
Engaging in proper physical training leads
to an improvement in these physical
attributes and physical fitness. The degree
of improvement is determined by several
factors, including training, diet, rest,
psychological factors, and genetics.
Aerobic and Anaerobic Fitness
The energy necessary to sustain life
and perform work is generated by the
cells in 1 of 2 ways: with the use of
oxygen and without oxygen. In general,
high-intensity activities derive their
energy mainly independent of oxygen,
while low-intensity activities use oxygen
to meet their energy requirements.
Historically, the utilization of oxygen to
generate energy has been referred to as
aerobic metabolism, and generating
energy without using oxygen has been
referred to as anaerobic metabolism.
Therefore, aerobic fitness refers to the
ability to provide the required energy for
a specific task in which the
cardiopulmonary system adequately
supplies the needed oxygen to the
working muscle cells. Aerobic activities
consist of repetitive, low-resistance
movements (eg, walking or cycling) that
last over a relatively extended period of
time (generally 5 minutes or more). Most
of the energy for such activities is
derived from the catabolism of
intracellular and adipose tissue–released
free fatty acids.
Anaerobic fitness refers to the body’s
capacity to provide the required energy
for a specific task independent of
oxygen. Anaerobic activities are
characterized by bursts of intense activity
lasting a comparatively short period of
time (sprinting, lifting of a heavy weight,
jumping, etc). The immediate energy
requirements (approximately initial 10
seconds) for such activities are met by
intramuscular stores of adenosine
triphosphate and phosphocreatine. This
system allows time for the glycolytic
pathways to generate an increasingly
greater percentage of energy and meet
the requirements for the activity lasting
beyond the initial phase and for the next
2 to 3 minutes. The energy demands for
work at maximal or near maximal
capacity beyond 2 to 3 minutes exceed
the capacity of the anaerobic pathways.
Consequently, the intensity of the activity
gradually decreases or ceases completely.
It is important to note that muscle cells
are never entirely aerobic or anaerobic.
Rather, these 2 energy systems (aerobic
and anaerobic) are almost always
working together in a harmonious way,
sharing the responsibility for providing
the energy requirements for the working
muscles and the entire body. However,
one is likely to be the predominant
system providing most of the energy for
the particular activity at hand.5(pp19-50)
Determining Exercise
Capacity: Direct Method
Open Circuit Spirometry
The “true” maximum aerobic capacity is
the maximum amount of oxygen
(referred to as maximal oxygen uptake
or Vo2 max) an individual can use during
work. This is assessed in laboratories by
open circuit spirometry. Vo2 max is
usually determined by a graded exercise
test. A brief description and rationale for
this procedure is as follows.
The individual breathes room air via a
mouth piece (nose occluded), connected
to an automated system (often termed a
metabolic cart) by plastic tubes. The
mouth piece is designed in such a way
that it allows the measurement of the
volume of expired air, while a small
sample of the expired air enters the
metabolic cart and is analyzed for its
oxygen and carbon dioxide content.
Oxygen uptake is determined by the
product of ventilation and the difference
between the O2 content of the ambient
and expired air. After resting samples are
taken, the individual is subjected to a
standardized exercise protocol on a
treadmill or stationary bike. The exercise
begins at a very low workload and
increases progressively until volitional
fatigue or until a clinical indication for
stopping is reached. The rate of increase
in external work depends on the
exercise protocol used, but it is typically
recommended that the test be
individualized to last between 8 and 12
minutes.
Since the relationship between the
increase in workload and oxygen
consumption is linear, oxygen
requirements also increase. At some
point the individual reaches a volitional
fatigue endpoint, and the test is
terminated. This level is referred to as
the maximal aerobic capacity of the
individual. The oxygen used by the
body at the point of fatigue is referred
to as the Vo2 max. The measurement of
Vo2 max implies that an individual’s
physiological limit has been reached.
True Vo2 max has historically been
defined by a plateau in Vo2 between
the final 2 exercise work rates and
requires that maximal effort be
achieved and sustained for a specified
period. Because this determination is
subjective, it can be difficult to define,
and is rarely observed when patients
with cardiovascular or pulmonary
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

3
vol. XX • no X American Journal of Lifestyle Medicine
disease are tested, the term peak VO2 is
more commonly used clinically to
express exercise capacity. Conversely,
the term Vo2 max is more often used to
describe exercise capacity in apparently
healthy individuals, in whom
achievement of a maximal physiological
response is more likely. Vo2 max is
expressed in milliliters of oxygen per
minute (mL/min) or milliliters of
oxygen per kilogram of body weight
per minute (mL/kg/min). The latter is
usually the preferred expression since it
allows comparisons between subjects of
different weights.
The advantage of the direct method is
that it allows an accurate assessment of
the exercise intensity of an individual
based on directly measured rather than
estimated aerobic capacity. However, it
is an elaborate method that requires
expensive equipment and trained
personal and is therefore cost-
prohibitive for large populations. For
this reason, it is mostly used in
individuals with specific clinical needs
and for research purposes5. For
someone who simply wishes to know
the appropriate exercise intensity
during his or her training, exercise
intensity can be easily determined by
the heart rate that corresponds to the
appropriate percentage of oxygen
consumption. Since heart rate and
oxygen uptake are continuously
recorded during the metabolic test, one
can easily match a desired percentage
of heart rate to the corresponding
oxygen consumption.
Determining Aerobic
Fitness by Standardized
Tests Using Indirect
Methods
The need for more practical methods
to assess aerobic capacity for large
populations led to the development of
standardized exercise tests and the
common practice of estimating energy
requirements from different workloads.
An indirect method for estimating the
fitness level of an individual is based on
the same principle as that for the direct
assessment of Vo2 max with one
exception; oxygen consumption is not
directly measured. Rather, it is estimated
based on treadmill speed and grade
using equations derived from the direct
assessment of Vo2 max. The actual
procedure is similar to that described
for the assessment of Vo2 max with the
exception that the individual is not
connected to a metabolic cart (no
breathing apparatus). While an
electrocardiogram is monitored, the
individual undergoes a standardized
exercise protocol on a treadmill or
stationary cycle ergometer. The most
commonly used exercise protocols in
the United States are described in Table
1, and these are discussed further
below. Exercise begins at a very low
workload and increases every 2 to 3
minutes depending on the exercise
protocol. The maximal workload is
determined from the speed and
elevation of the treadmill, or the
resistance if a cycle ergometer is used.
Heart rate is continuously monitored
and recorded during the entire test, and
blood pressure is recorded every 2 to 3
minutes.
The workload is estimated for each
exercise stage based on the speed and
elevation of the treadmill. This
estimation is based on comparison
studies in which the energy
requirements (oxygen consumption)
were measured directly with open circuit
spirometry. In general, the amount of
oxygen used during resting conditions is
approximately 3.5 mL of oxygen per
kilogram of body weight per minute (3.5
mL O2/kg/min). This value (the resting
metabolic rate) is termed 1 metabolic
equivalent or 1 MET. Naturally, any
increase beyond the 1-MET level
represents higher total body oxygen
consumption. Based on this rationale,
several standardized exercise protocols
have been developed to assess the MET
level of individuals for clinical and other
reasons. The MET level achieved on
termination of the test (the individual
reaches volitional fatigue) represents the
peak aerobic capacity of the individual.
Because each MET is equal to
approximately 3.5 mL O2/kg/min, Vo2
max can be estimated by multiplying the
MET level achieved by 3.5.5 It is
important to note that exercise capacity
assessed by such exercise tests is
associated with the physical activity
status of the individual. However, the
ability to perform aerobic work is also
determined by age and gender, as well
as an important genetic component.6,7
Exercise Protocols
The purpose of the test and the person
tested are important considerations in
selecting the protocol. Exercise testing
may be performed for diagnostic
purposes, for functional assessment, or
for risk stratification. An often ignored
but nevertheless consistent
recommendation in the recent exercise
testing guidelines is that the protocol be
individualized for the patient being
tested.8,9 For example, a maximal,
symptom-limited test on a relatively
demanding protocol would not be
appropriate (or very informative) for a
severely limited patient. Likewise, a very
gradual protocol might not be useful for
an apparently healthy, active person. Use
of submaximal testing, gas exchange
techniques, the presence of a physician,
and the exercise mode and protocol
should be determined by considering the
person being tested and the goals of the
test.
Commonly used exercise protocols,
their stages, and the MET level for each
stage are outlined in Table 1. The most
suitable protocols for clinical testing
should include a low-intensity warm-up
phase followed by progressive,
continuous exercise in which the
demand is elevated to a patient’s
maximal level within a total duration of 8
to 12 minutes.8-12 In the absence of gas
exchange techniques, it is important to
report exercise capacity in METs rather
than exercise time, so that exercise
capacity can be compared uniformly
between protocols. METs can be
estimated from any protocol using
standardized equations that have been
put into tabular form.8,12 In general, 1
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

4
Mon • Mon XXXXAmerican Journal of Lifestyle Medicine
Table 1.
Commonly Used Treadmill and Bicycle Exercise Protocols.
Bruce Protocol
Stage Minutes Speed (mph) % Grade METs
1 3 1.7 10 4.6
2 3 2.5 12 7.0
3 3 3.4 14 10.2
4 3 4.2 16 13.5
5 3 5.0 18 17.2
6 3 5.5 20 20.4
7 3 6.0 22 23.8
Modified Bruce
Stage Minutes Speed (mph) % Grade METs
1 3 1.7 0 2.3
2 3 1.7 5 3.5
3 3 1.7 10 4.6
4 3 2.5 12 7.0
5 3 3.4 14 10.2
6 3 4.2 16 13.5
7 3 5.0 18 17.2
8 3 5.5 20 20.4
9 3 6.0 22 23.8
Balke-Ware
Stage Minutes Speed (mph) % Grade METs
1 3 3.3 1 4.0
2 3 3.3 2 4.4
3 3 3.3 3 4.9
4 3 3.3 4 5.3
5 3 3.3 5 5.8
6 3 3.3 6 6.3
7 3 3.3 7 6.7
8 3 3.3 8 7.2
(continued)
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

5
vol. XX • no X American Journal of Lifestyle Medicine
Balke-Ware
Stage Minutes Speed (mph) % Grade METs
9 3 3.3 9 7.6
10 3 3.3 10 8.1
11 3 3.3 11 8.5
12 3 3.3 12 9.0
13 3 3.3 13 9.4
14 3 3.3 14 9.9
15 3 3.3 15 10.3
16 3 3.3 16 10.8
17 3 3.3 17 11.3
18 3 3.3 18 11.7
19 3 3.3 19 12.2
20 3 3.3 20 12.6
21 3 3.3 21 13.1
22 3 3.3 22 13.5
23 3 3.3 23 14.0
24 3 3.3 24 14.4
25 3 3.3 25 14.9
26 3 3.3 26 15.4
Balke
Stage Minutes Speed (mph) % Grade METs
1 2 3.0 2.5 4.3
2 2 3.0 5 5.4
3 2 3.0 7.5 6.4
4 2 3.0 10 7.4
5 2 3.0 12.5 8.5
6 2 3.0 15 9.5
7 2 3.0 17.5 10.5
Table 1. (continued)
(continued)
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

6
Mon • Mon XXXXAmerican Journal of Lifestyle Medicine
Naughton
Stage Minutes Speed (mph) % Grade METs
1 2 1 0 1.8
2 2 2 0 2.5
3 2 2 3.5 3.5
4 2 2 7.0 4.5
5 2 2 10.5 5.4
6 2 2 14.0 6.4
7 2 2 17.5 7.4
8 2 2 21.0 8.3
Standard Bicycle Protocol
Stage Minutes
Revolutions per
Minute Resistance (kg m/min) Resistance (Watts) METs
1 2 or 3 50 150 25 3.1
2 2 or 3 50 300 50 4.2
3 2 or 3 50 450 75 5.3
4 2 or 3 50 600 100 6.4
5 2 or 3 50 750 125 7.5
6 2 or 3 50 900 150 8.6
Abbreviation: METs, metabolic equivalents.
Table 1. (continued)
MET represents an increment on the
treadmill of approximately 1.0 mph or
2.5% grade. On a cycle ergometer, 1 MET
represents an increment of
approximately 20 W (120 kg m/min) for
a 70-kg person. The assumptions
necessary for predicting MET levels from
treadmill or cycle ergometer work rates
(including not holding the handrails, that
oxygen uptake is constant [ie, steady-
state exercise is performed], that the
subject is healthy, and that all people are
similar in their walking efficiency) raise
uncertainties as to the accuracy of
estimating the work performed for an
individual patient. For example, the
steady-state requirement is rarely met for
most patients on most exercise protocols;
most clinical testing is performed among
patients with varying degrees of
cardiovascular or pulmonary disease; and
people vary widely in their walking
efficiency.13 It has therefore been
recommended that a patient be ascribed
a MET level only for stages in which all
or most of a given stage duration has
been completed.14
Ramp Testing
An approach to exercise testing that
has gained interest in recent years is the
ramp protocol, in which work increases
constantly and continuously. In 1981,
Whipp et al15 first described
cardiopulmonary responses to a ramp
test on a cycle ergometer, and many of
the gas exchange equipment
manufacturers now include ramp
software. Treadmills have also been
adapted to conduct ramp tests.12,16,17 The
ramp protocol uses a constant and
continuous increase in metabolic
demand that replaces the “staging” used
in conventional exercise tests. The
increase in workload is tailored for each
patient, based on information gathered
prior to the test regarding the level of
physical activity of the individuals and
symptoms. The uniform increase in work
allows for a steady increase in
cardiopulmonary responses and permits
a more accurate estimation of oxygen
uptake.12,18 The recent call for
“optimizing” exercise testing8,10,12,15
would appear to be facilitated by the
ramp approach because large work
increments are avoided and increases in
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

7
vol. XX • no X American Journal of Lifestyle Medicine
work are individualized, permitting test
duration to be targeted. Because there
are no stages per se, the errors
associated with predicting exercise
capacity alluded to previously are
lessened.2,8,12
Cycle Ergometer Protocols
The most modern, electronically braked
cycle ergometers consist of a single
wheel and have controllers that permit
ramp testing, in which the work rate
increments can be individualized in
continuous fashion. Cycle ergometers are
relatively inexpensive, minimize the risk
of falling, can be moved from place to
place and can accurately predict energy
output.
When assessing maximal aerobic
power, it is recommended that the initial
workload selected is low and increase
gradually. It is recommended that the
pedaling frequency should be
maintained at 50 to 60 revolutions per
minute. Although there are specific
bicycle protocols named for early
researchers in Europe, such as Astrand,19
bicycle ergometer protocols tend to be
more generalized than for the treadmill.
For example, 15- to 25-W increments per
2-minute stage are commonly used for
patients with cardiovascular disease,
whereas for apparently healthy adults or
athletic individuals, appropriate work
rate increments might typically be
between 40 and 50 W/stage.
Submaximal Testing
In general, maximal, symptom-limited
tests are not considered appropriate
until 1 month after myocardial infarction
or cardiac surgery. Thus, submaximal
exercise testing has an important role
clinically for predischarge, post–
myocardial infarction, or post–bypass
surgery evaluations. Submaximal tests
have been shown to be important in risk
stratification17,20-23 for making
appropriate activity recommendations,
for recognizing the need for
modification of the medical regimen, or
for further interventions in patients who
have sustained a cardiac event. A
submaximal, pre-discharge test appears
to be as predictive for future events as a
symptom-limited test among patients
less than 1 month after myocardial
infarction. Submaximal testing is also
appropriate for patients with a high
probability of serious arrhythmias. The
testing endpoints for submaximal testing
have traditionally been arbitrary but
should always be based on clinical
judgment. A heart rate limit of 140
beats/min and a MET level of 7 are often
used for patients younger than 40 years,
and limits of 130 beats/min and a MET
level of 5 are often used for patients
older than 40 years. For those using
beta-blockers, a Borg perceived exertion
level in the range of 7 to 8 (1-10 scale)
or 15 to 16 (6-20 scale) are conservative
endpoints. The initial onset of symptoms
including fatigue, shortness of breath, or
angina, is also indications to stop the
test. A low-level protocol should be
used, that is, one that uses no more than
1-MET increments per stage. The
Naughton protocol23 is commonly used
for submaximal testing. Ramp testing is
also ideal for this purpose because the
ramp rate (such as 5 METs achieved
over 10-minute duration) can be
individualized depending on the patient
tested.12
Submaximal tests can be used to assess
the capacity of apparently healthy
individuals to exercise safely or to
estimate Vo2 max by extrapolation. The
premise of estimating Vo2 max from a
submaximal test is based on the linear
relationship between heart rate and
oxygen consumption, provided that the
work is aerobic in nature. In submaximal
test protocols, the heart rate at each
workload is plotted against the workload
and extrapolated to Vo2 max at an
age-predicted maximal heart rate
(typically 220 − age). Vo2 max can be
calculated using prediction equations2 or
estimated from values obtained by
commonly used exercise protocols if the
following assumptions are met: (a) the
workload is reproducible, (b) a steady-
state heart rate is obtained during each
stage, and (c) a linear relationship exists
between heart rate and oxygen
consumption over a wide range of
values. Examples of submaximal tests
used to estimate peak Vo2 include the
YMCA test, the Astrand test, and
others.19,24,25
It is important to note that the accuracy
of such tests is affected by the
assumption of linearity between heart
rate and oxygen consumption as exercise
intensity increases. Although this
assumption generally holds, especially in
low-to-moderate workloads, differences
in maximal heart rate, variability in
maximal heart rate estimation by the
formula 200 − age, day-to-day heart rate
variability and mechanical efficiency
among individuals are not considered.
Consequently, the Vo2 max predicted
from submaximal heart rate is generally
within ±10% to 20% of the individual’s
true Vo2 max value. The heart rate–O2
consumption linear relationship can no
longer be assumed when patients are
treated with medications (beta-blockers)
that attenuate resting and exercise heart
rate. This is especially true at peak
exercise heart rates.
Walk Tests for
Cardiorespiratory
Fitness Assessment
A number of walking tests have also
been developed for estimating
cardiorespiratory fitness or assessing
functional status of healthy individuals,
and patients with cardiovascular or
pulmonary disease in clinical settings.
Advantages of walk tests include the fact
that they are easy to perform and are
relatively inexpensive, and thus can be
applied to large populations. It is
important to keep in mind that equations
developed to predict Vo2 max were
derived from a steady-state submaximal
aerobic exercise. Therefore, their
accuracy in predicting Vo2 max is only
adequate during steady-state submaximal
aerobic work. Walking equations
overestimate Vo2 during non–steady-state
exercise conditions, especially when
contribution from anaerobic metabolism
is large. In general, they are most
accurate for speeds of 1.9 to 3.7 mph
and highly inaccurate for speeds
between 3.7 and 5.0 mph. These speeds
are in the range of transition from a
walking to running motion and neither
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

8
Mon • Mon XXXXAmerican Journal of Lifestyle Medicine
walking nor running equations are
accurate in estimating peak Vo2 and
therefore should not be applied.
Walking tests include (a) the 6-minute
walk test, (b) the Cooper 12-minute test,
(c) the 1.5 mile test, and (d) the
Rockport 1-mile fitness walking test.2
The 6-minute walk test is popular for
assessing functional status in clinical
settings and is mostly used among
diseased populations such as patients
with heart failure, stroke, and peripheral
vascular disease. The objective of the test
is to cover the greatest distance by
walking in 6 minutes. Its obvious
advantages are that it requires practically
no equipment (other than a stopwatch)
and little time.
Although the association between
6-minute walk performance and exercise
capacity is only modest, peak Vo2 can be
estimated from 6-minute walk distance
by the following multivariate equation
along with other readily available
information26:
Peak VO =[0.02 distance (m)]
[0.191 age(y)][0.07 weight (kg)
2×
−× −× ]]
[0.09height(cm)] [0.26RPP (1
0)
]
-3
+× +× ×
where m = meters, kg = kilogram, cm =
centimeters, y = years, and RPP = rate
pressure product (systolic blood pressure
[mm Hg] × heart rate).
The Cooper 12-minute test is based on
a similar concept (covering the greatest
distance in 12 minutes), while the
objective of the 1.5-mile test is to run the
distance (1.5 miles) in the shortest period
of time. Unlike the 6-minute walk test,
both these tests are more suitable for
healthy, younger individuals. They also
require little or no additional equipment
and can be administered to large
populations.
The Rockport 1-mile fitness walking
test involves covering a 1-mile distance
in the shortest period of time. However,
in addition to the time required to cover
the 1-mile distance, the test uses peak
heart rate achieved during the last
minute of the walk, and an estimate of
peak Vo2 is derived. If heart rate
monitoring is not an option during the
test, a 10-second heart rate obtained
immediately after the completion of the
test can be used as an alternative.
However, this is likely to overestimate
peak Vo2 compared with that calculated
when heart rate is obtained during the
last minute of the walk.
Step Test
A number of step test have been
developed over the years. One common
step test that has been used consists of
stepping up and down a step of a certain
height and fixed rate. The rate of
stepping is established with a
metronome set at 88 beats/min. The
stepping cadence has four counts: up
(right foot), up (left foot), down (right
foot), down (left foot). The stepping
height is approximately 40 cm.
Cardiorespiratory fitness is estimated by
assessing the post exercise heart rate
response. The heart rate is measured for
15 seconds immediately after the
cessation of the test and while the
participant is standing. The 15-second
heart rate is then converted to beats/min
(15-second heart rate × 4) and compared
with established percentile rankings
(Table 2). The relationship between
recovery heart rate and Vo2 max is
inverse. The estimated aerobic capacity
findings of the step test were validated
by measuring the Vo2 max in a group of
untrained men and women who also
performed both tests.27 Consequently, the
following equations were established:
Men: VO max=111.33
[0.42steptestheart rate (beats /min)]
2
−×−
Women: VO max=65.81
[0.1847 step test heartrate(beats/min)]
2
−×−
The step test is a realistic alternative to
other test in field studies. It requires little
or no equipment, little practice or skill
and can be implemented to a large
cohort. However, it is more difficult to
standardize, difficult to monitor heart
rate or blood pressure. In addition, the
risk of falling at higher stepping paces is
relatively high.
Muscular Fitness
The American College of Sports
Medicine defines muscular fitness as the
ability of the muscle to perform tasks
that require muscular strength or
muscular endurance. The role of
muscular strength in the performance of
activities of daily living and exercise, as
well as in the prevention of chronic
disease, is increasingly being
recognized.28,29
Traditionally, resistance exercise training
or strength training is the preferred mode
for increasing muscular strength.
Resistance exercises can be performed by
either using free-standing weight or
weights housed within an apparatus
(weight training machines). Such
apparatuses use pulleys to allow the
displacement of a preselected weight by
the individual. Both free weights and
strength training apparatuses are similarly
effective in promoting muscular fitness.
However, weight training machines offer a
greater degree of safety and efficiency,
but they are more expensive.
Strength is an important component of
fitness assessment since it has
implications for an individual’s functional
capabilities, disability, bone health, and
insulin resistance and has been shown to
have a strong association with long-term
outcomes.30,31 Muscular strength is
inversely and independently associated
with death from all causes and cancer in
men, even after adjusting for
cardiorespiratory fitness and other
potential confounders.31
Muscular Strength
Muscular strength is defined as the
ability of the muscle or muscle groups
to exert force during a voluntary
contraction.1 The maximal force a
muscle or group of muscles can exert is
traditionally assessed by tests that
require maximum effort against the
greatest resistance one can move
through the full range of motion once.
This is known as the 1-repetition
maximum (1-RM). A percentage of the
1-RM is then used to determine the
number of repetitions one should
perform to enhance the strength for a
specific muscle. Generally, 8 to 12
repetitions at 40% to 60% of 1-RM are
sufficient to enhance muscular strength.
An appropriate resistance training
regimen involves performing these 8 to
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

9
vol. XX • no X American Journal of Lifestyle Medicine
12 repetitions 1 to 3 times, 2 to 3 times
per week. While intensities as much as
80% and relatively low repetitions (such
as 3-5) have been shown to be quite
effective for rapid strength gains, this
approach is generally limited to athletes
whose performance requires great
amounts of force.
It is important to note that intensity
for resistance exercise is not always
easy to determine and the 1-RM does
not depict a true intensity. The
number of repetitions and the
percentage of resistance based on
1-RM differ significantly between
individuals and muscle groups. Thus,
the 1-RM should only be used as a
general guideline.2
Muscular Endurance
Muscular endurance is defined as the
ability of the muscle or muscle groups to
perform repetitive contractions over a
period of time against a submaximal
resistance, such as lifting a set amount of
weight several times.2 Muscular
endurance is assessed by tests requiring
more than 12 repetitions. A simple test of
muscular endurance is the maximum
number of push-ups or sit-ups one can
execute without rest.2
Anaerobic Power
Because anaerobic power is an
important determinant of athletic
performance requiring high levels of
exertion over short periods, tests have
been developed to measure the capacity
of the anaerobic energy systems. As
mentioned, the immediate energy
requirements for such high-intensity
(anaerobic) activities are met by
intramuscular stores of adenosine
triphosphate and phosphocreatine for
initial 10 seconds (approximately) and
by the glycolytic pathways for activities
lasting beyond 10 seconds.
One of the more common tests of this
type is the Wingate test, which involves
30 to 120 seconds of high-intensity
effort on a cycle ergometer. After
adequate warm-up, the subject begins
pedaling as fast as possible without
resistance. Within just seconds, a fixed
resistance is applied to the flywheel,
while the subject continues pedaling at
an all-out effort. The resistance is based
on body mass (originally 0.075 kp per
kg body mass, though this may vary)
and is applied after initial inertia and
unloaded resistance are overcome.
Peak power is considered to represent
the highest mechanical power
generated during any 3- to 5-second
period during the test; average power is
the average of the total power
generated during the test. An
underlying assumption of the Wingate
test is that peak power reflects the
energy-generating capacity of the
oxygen-independent high-energy
phosphates, whereas average power is
a representation of the individual’s
glycolytic capacity, but it is not a
precise measure of this capacity.32,33 In
studies comparing the Wingate test
results with athletic performance and
laboratory findings, it has been
demonstrated to be a good index of
these energy systems, although studies
are mixed in terms of its ability to
predict success in events requiring high
exercise intensity.33
Table 2.
Predicted Aerobic Capacity Estimated by the 15-Second Recovery Heart Rate (HR)
Attained Immediately After Cessation of the Step Test21.
Percentile
Ranking
Recovery
HR Female
Predicted Vo2max
(mL/kg/min)
Recovery
HR Male
Predicted Vo2max
(mL/kg/min)
100 128 42.2 120 60.9
95 140 40.0 124 59.3
90 148 38.5 128 57.6
85 152 37.7 136 54.2
80 156 37.0 140 52.5
75 158 36.6 144 50.9
70 160 36.3 148 49.2
65 162 35.9 149 48.8
60 163 35.7 152 47.5
55 164 35.5 154 46.7
50 166 35.1 156 45.8
45 168 34.8 160 44.1
40 170 34.4 162 43.3
35 171 34.2 164 42.5
30 172 34.0 166 41.6
25 176 33.3 168 40.8
20 180 32.6 172 39.1
15 182 32.2 176 37.4
10 184 31.8 178 36.6
5 196 29.6 184 34.1
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from

10
Mon • Mon XXXXAmerican Journal of Lifestyle Medicine
References
1. Caspersen CJ, Kristenson GM. Physical
activity, exercise, and physical fitness:
definitions and distinctions for health-
related research. Public Health Rep.
1985;100:126-131.
2. Whaley MH, Brubaker PH, Otto RM, eds.
ACSM’s Guidelines for Exercise Testing
and Prescription. 7th ed. Philadelphia, PA:
Lippincott Williams & Wilkins; 2006.
3. Kokkinos P, Myers J, Faselis C, et al.
Exercise capacity and mortality in
older men: a 20-year follow-up study.
Circulation. 2010;122:790-797.
4. Kokkinos P, Myers J. Exercise and physical
activity: clinical outcomes and applications.
Circulation. 2010;122:1637-1648.
5. Kokkinos P. Physical Activity and
Cardiovascular Disease Prevention.
Sudbury, MA: Jones & Bartlett; 2010.
6. Bouchard C, Daw EW, Rice T, et al. Familial
resemblance for VO
2max
in the sedentary
state: the HERITAGE family study. Med Sci
Sports Exerc. 1998;30:252-258.
7. Pérusse L, Tremblay A, Leblanc C,
Bouchard C. Genetic and environmental
influences on level of habitual physical
activity and exercise participation. Am J
Epidemiol. 1989;129:1012-1022.
8. Gibbons RJ, Balady GJ, Bricker JT, et
al. ACC/AHA 2002 guideline update for
exercise testing. A report of the ACC/
AHA Task Force on practice guidelines
(Committee on Exercise Testing). J Am Coll
Cardiol. 2002;40:1531-1540.
9. Myers J, Froelicher VF. Optimizing the
exercise test for pharmacologic studies in
patients with angina pectoris. In: Ardissino
D, Savonitto S, Opie LH, eds. Drug
Evaluation in Angina Pectoris. Pavia, Italy:
Kluwer Academic; 1994:41-52.
10. Webster MW, Sharpe DN. Exercise testing
in angina pectoris: the importance of
protocol design in clinical trials. Am Heart
J. 1989;117:505-508.
11. Buchfuhrer MJ, Hansen JE, Robinson
TE, Sue DY, Wasserman K, Whipp BJ.
Optimizing the exercise protocol for
cardiopulmonary assessment. J Appl
Physiol. 1983;55:1558-1564.
12. Myers J, Buchanan N, Walsh D, et al.
Comparison of the ramp versus standard
exercise protocols. J Am Coll Cardiol.
1991;17:1334-1342.
13. Myers J. Essentials of Cardiopulmonary
Exercise Testing. Champaign, IL: Human
Kinetics; 1996.
14. Arena R, Myers J, Williams MA, et al.
Assessment of functional capacity in
clinical and research settings: a scientific
statement from the American Heart
Association Committee on Exercise,
Rehabilitation, and Prevention of the
Council on Clinical Cardiology and the
Council on Cardiovascular Nursing.
Circulation. 2007;116:329-343.
15. Whipp BJ, Davis JA, Torres F, Wasserman
K. A test to determine parameters of
aerobic function during exercise. J Appl
Physiol. 1981;50:217-221.
16. Myers J, Buchanan N, Smith D, et
al. Individualized ramp treadmill:
observations on a new protocol. Chest.
1992;101:2305-2415.
17. Porszasz J, Casaburi R, Somfay A, et al. A
treadmill ramp protocol using simultaneous
changes in speed and grade. Med Sci Sports
Exerc. 2003;35:1596-1603.
18. Myers J, Bellin D. Ramp exercise protocols
for clinical and cardiopulmonary exercise
testing Sports Med. 2000;30:23-29.
19. Astrand PO, Rodahl K. Textbook of Work
Physiology. 3rd ed. New York, NY:
McGraw-Hill; 1986.
20. Chang JA, Froelicher VF. Clinical and
exercise test markers of prognosis in
patients with stable coronary artery disease.
Curr Probl Cardiol. 1994;19:533-538.
21. Froelicher ES. Usefulness of exercise testing
shortly after acute myocardial infarction for
predicting 10-year mortality. Am J Cardiol.
1994;74:318-323.
22. Olona M, Candell-Riera J, Permanyer-
Miralda G, et al. Strategies for prognostic
assessment of uncomplicated first
myocardial infarction: 5-year follow-up
study. J Am Coll Cardiol. 1995;25:815-822.
23. Naughton J, Balke B, Nagle F.
Refinements in methods of evaluation
and physical conditioning before and
after myocardial infarction. Am J Cardiol.
1964;14:837-843.
24. Maritz JS, Morrison JF, Peter J. A practical
method of estimating an individual’s
maximal oxygen uptake. Ergonomics.
1961;4:97-122.
25. Golding LA. YMCA Fitness Testing and
Assessment Manual. Champaign, IL.
Human Kinetics; 1989.
26. Cahalin LP, Mathier MA, Semigran MJ, Dec
GW, DiSalvo TG. The six-minute walk test
predicts peak oxygen uptake and survival
in patients with advanced heart failure.
Chest. 1996;110:325-332.
27. McArdle WD, Katch FI, Pechar GS,
Jacobson L, Ruck S. Reliability and
interrelationships between maximal oxygen
intake, physical work capacity and step-test
scores in college women. Med Sci Sports.
1972;4:182-186.
28. Artero EG, Lee DC, Ruiz JR, et al.
Prospective study of muscular strength
and all-cause mortality in men with
hypertension. J Am Coll Cardiol.
2011;57:1831-1837.
29. Fujita Y, Nakamura Y, Hiraoka J, et al.
Physical-strength tests and mortality
among visitors to health-promotion
centers in Japan. J Clin Epidemiol.
1995;48:1349-1359.
30. Katzmarzyk PT, Craig CL. Musculoskeletal
fitness and risk of mortality. Med Sci Sports
Exerc. 2002;34:740-744.
31. Ruiz JR, Sui X, Lobelo F, et al. Association
between muscular strength and mortality
in men: prospective cohort study. BMJ.
2008;337:92-95.
32. Vandewalle D, Gilbert P, Monod H.
Standard anaerobic tests. Sports Med.
1987;4:268-289.
33. Bar-Or O. The Wingate anaerobic test: an
update on methodology, reliability and
validity. Sports Med. 1987;4:381-394.
at US DEPT OF VETERAN AFFAIRS on January 23, 2014ajl.sagepub.comDownloaded from