Journal of Gerontology: MEDICAL SCIENCES
2005, Vol. 60A, No. 1, 57–66
Copyright 2005 by The Gerontological Society of America
Review Article
Maximal Aerobic Capacity Testing of
Older Adults: A Critical Review
Deanna L. Huggett, Denise M. Connelly, and Tom J. Overend
School of Physical Therapy, University of Western Ontario, London, Canada.
Most of the data that describe maximal oxygen uptake (VO2max) and the requirements for its attainment have been
developed using young adults as subjects. Many older adults are unable to satisfactorily complete a maximal exercise
effort in a standard exercise stress test. This review describes exercise tests currently available to measure VO2max in
older adults. PubMed and CINAHL databases were searched for studies including healthy individuals older than
65 years with reproducible descriptions of the testing protocol. The research on VO2max testing in healthy individuals older than 65 years is limited, does not describe the protocols in detail, and/or lacks information on the psychometric properties of the exercise tests. There is a need for refinement of the few existing protocols for testing aerobic
capacity in older adults, as well as the development of new protocols specifically applicable to older adults. Consensus
on the criteria defining VO2max attainment during exercise in older adults is required, as well as agreement on the
most appropriate exercise protocols and equipment, specific to older adults, to successfully fulfil these criteria.
AXIMAL oxygen uptake (VO2max), also known as
functional aerobic capacity, represents the maximal
rate of oxygen utilization by exercising muscles and is
considered the gold standard measure of the functional limit
of the cardiorespiratory system (1,2). Functional aerobic
capacity can be objectively measured with an exercise stress
test and is useful in assessing physical fitness, diagnosing
and defining the prognosis of ischemic heart disease, developing an exercise prescription, and guiding cardiac rehabilitation (3). Assessment of VO2max also allows clinicians to
identify individuals who may have difficulty performing
various functional tasks, as the energy requirements (oxygen uptake) for many physical tasks have been determined
and are now readily available (4,5).
A maximal exercise test with direct measurement of
oxygen uptake is considered the most accurate method of
assessing aerobic power, but different values may be
obtained for the same individual when different testing
modalities are used (6,7). Exercise stress testing is most
commonly carried out using a treadmill or bicycle ergometer.
The treadmill provides a more familiar and functional
exercise modality, namely walking, and has been shown to
have greater diagnostic sensitivity than the bicycle ergometer
(8). However, exercise on a treadmill may not be appropriate
for many older individuals with balance deficits or conditions, such as arthritis, in which weight-bearing exercise may
cause excessive joint pain. VO2max values during cycle
ergometer exercise average 11% lower (range, 8%–15%)
than those during treadmill exercise, primarily because of the
smaller volume of exercising muscle mass (9–12). Regardless of the modality used, an appropriate exercise protocol
should be followed.
VO2max is known to decline with age (13–15). The agerelated rate of decline in VO2max differs among investigations and is highly variable among individuals within
M
a population (16). The most commonly cited estimation is
that VO2max declines at a rate of 1% per year after the third
decade of life (17). The decreased cardiorespiratory function
and muscular performance associated with advancing age
and/or inactivity can significantly diminish an individual’s
functional capacity (18–20). Many sedentary older adults
are of an age that theoretically places them very close to an
aerobic capacity threshold. Any further decline may render
them unable to perform their activities of daily living and
thus impair their ability to live independently (19,21,22).
The technical requirements of measuring VO2max and concerns regarding patient safety often limit direct measurement
of VO2max (23). Thus, it is often calculated indirectly through
linear regression equations relating exercise performance to
oxygen uptake (24,25). Such prediction equations, however,
tend to be population specific and valid only through
a limited age range. The prevalence of asymptomatic
coronary artery disease and the coexistence of other chronic
conditions and physical limitations result in distinct differences between younger and older adults (26). Many older
persons have at least one, if not multiple, chronic medical
conditions, such as arthritis, hypertension, or diabetes (27).
The involvement of a variety of medical conditions, many of
which may be asymptomatic, may make prediction equations
inaccurate for older adults.
The burden of chronic conditions and physical limitations
increases substantially with age and contributes to the difficulty of measuring VO2max in older persons (26,28). Measurement of VO2max is particularly useful for fit and highly
motivated persons, but it depends heavily on subjective
factors such as muscle fatigue, perceived exhaustion, and
level of motivation, as well as the clinician’s willingness to
allow participants to exercise to exhaustion (29).
The requirements for attaining VO2max are variable in the
literature and include a measurement of the ratio between
57
58
HUGGETT ET AL.
carbon dioxide production and oxygen consumption (VCO2/
VO2) (30), or respiratory exchange ratio (RER), of .1.0
(31,32) to .1.15 (33); a peak exercise heart rate (HR) of at
least 85% of age-predicted maximum (34) or a HR within 10
beats per minute (bpm) of age-predicted maximum (35); and
a plateau in oxygen consumption, defined variously as an
increase in oxygen uptake of ,1.5 ml/min per kg (36) to
,2.0 ml/min per kg (17,37). Borg’s Rating of Perceived
Exertion scale is now frequently used as a marker as well
(38,39). However, most of the data that describe VO2max and
the requirements for its attainment have been developed
using young adults as subjects (40). These data have
subsequently been adapted or extrapolated for use in subjects
of various ages. Those studies that do describe maximal
aerobic capacity in older adults or declines in fitness with
age are based on samples of subjects that included either
relatively few older subjects, or older subjects who were
selected on the basis of known physical activity patterns
(13,41,42). Moreover, most of these studies included
virtually no subjects older than 70 years of age (30,43).
Many older adults are unable to satisfactorily complete
a maximal exercise effort in a standard exercise stress test
(26). The increment of VO2 accepted as a plateau in younger
subjects could represent 10% or more of the total VO2max of
an older adult or unfit individual (17,37). The high initial
exercise rates and the long duration of exercise in the
various protocols often prevent successful completion of
exercise stress tests in older adults (40). The effort of the
older adults is not necessarily limited by the power of the
heart and lungs, but more often by factors such as dyspnea
(44,45), fear of overexertion (46,47), muscular weakness
(44,45), poor motivation (44), or the appearance of electrocardiographic abnormalities (48). Currently, there is a debate
regarding (a) the need for attainment of a plateau in VO2, or
(b) whether the peak VO2 (VO2peak) value obtained is
sufficient to report as VO2max. VO2peak represents the level
of oxygen consumption recorded at the peak workload (30).
Thus agreement is needed on what is acceptable as
a maximal or near-maximal effort in older adults (30).
This critical review describes exercise tests currently
available to measure the maximal aerobic capacity of older
adults. A summary of the protocols used with healthy participants older than 65 years of age is included, and recommendations are made for use of these tests in clinical and
research settings. Potential areas for future research are also
outlined.
METHODS
Literature Search
A computer search was conducted of the English language
medical literature using the databases PubMed (1966
through February 2004) and CINAHL (1982 through
February 2004). Combinations of the following key words
were used: ‘‘exercise test,’’ ‘‘maximal aerobic capacity,’’
‘‘VO2max,’’ ‘‘maximal oxygen consumption,’’ ‘‘exercise
capacity testing,’’ ‘‘older adults,’’ and ‘‘aging.’’ We also
conducted a manual search of the references of retrieved
articles to identify additional potential studies. Investigations
published only in abstract form were not included, and no
attempt was made to contact experts in the field to uncover
unpublished material.
Inclusion and Exclusion Criteria
The following criteria for inclusion were used: (a) English
language studies published in peer-reviewed journals; (b)
older adult subjects (65 years); (c) healthy (e.g., nonischemic electrocardiographic response) subjects; and (d)
inclusion of a reproducible description of the exercise testing
protocol used. Healthy subjects were deemed to have no
known medical conditions. Only data related to the protocols
used and the results of VO2max testing were included in this
review. Using the above criteria, we reviewed the search
results from PubMed and CINAHL and decided which
articles to retrieve. Retrieved articles fulfilling the inclusion criteria were reviewed, and data were extracted and
summarized. Quality of the studies was not used as an
exclusion criterion but has been addressed in the discussion
of the articles included in this review.
RESULTS OF LITERATURE SEARCH
A compilation of the available literature on protocols for
VO2max testing in older adults follows in alphabetical order.
An overview of the available tests and their relevant studies
is provided, followed by an evaluation of the protocols and
discussion. Maximal treadmill test protocols are summarized in Table 1, and maximal cycle ergometer test protocols
are summarized in Table 2.
Maximal Treadmill Tests
Foster and colleagues (36) tested the reproducibility of
VO2max values in eight older women (80.6 6 3.7 years).
The researchers used a continuous incremental treadmill
test, starting at a 0% grade and a speed of 40 m/min
(1.5 mph, 2.40 km/h). The treadmill speed was held constant throughout the test, and the elevation was increased by
1% every 3 minutes. Each subject was tested on three occasions. The results indicated that VO2max is reproducible for
older women, with significant intra-individual correlation
coefficients for all comparisons (r ¼ 0.70–0.84).
Hollenberg and colleagues (30) tested 1101 subjects
between 55 and 94 years of age (438 men, mean age 67.8 6
7.8 years; 663 women, mean age 67.8 6 7.9 years), and used
the Cornell modification of the Bruce treadmill protocol.
This modification consists of eleven 2-minute stages (49).
The test starts at 1.7 mph (2.72 km/h) and a 0% grade and
increases in a step-like manner to a final stage at 5 mph
(8 km/h) with an 18% grade (see Table 1 for details).
Hollenberg and colleagues suggest that the Cornell exercise
protocol might be appropriate for use in large epidemiologic
studies of healthy adults older than age 65 because of the
small increments in work rate that produced average test
durations of 10 minutes, close to the recommended target for
such tests.
Katzel and colleagues (50) performed a longitudinal
follow-up on male athletes compared to sedentary counterparts. Subjects included 42 athletes with a baseline age of
63.4 6 1.0 years and a follow-up age of 71.4 6 1.1 years,
as well as 47 sedentary men with a baseline age of 61.1 6
0.9 years and a follow-up age of 70.4 6 0.9 years. VO2max
VO2max TESTING IN OLDER ADULTS
59
Table 1. Maximal Treadmill Protocols for Older Adults
Authors (Ref.)
Subjects
Protocol
Foster et al.,
1986 (36)
8 older women (80.6 6 3.7 y)
Continuous incremental treadmill test
Initiated at 0% grade, speed 40 m/min (1.5 mph, 2.40 km/h)
Speed held constant throughout, elevation increased 1% every 3 min
Hollenberg et al.,
1998 (30)
1101 subjects 55–94 y of age
438 men (67.8 6 7.8 y)
663 women (67.8 6 7.9 y)
Cornell modification of the Bruce protocol (eleven 2-min stages):
Initiated at 1.7 mph (2.72 km/h), grade 0%
Step-like increases to a final stage at 5 mph (8 km/h) with 18% grade
Stage
Elapsed time (min)
Speed (mph)
Grade (%)
2
4
6
8
10
12
14
16
18
20
22
1.7
1.7
1.7
2.1
2.5
3.0
3.4
3.8
4.2
4.6
5.0
0
5
10
11
12
13
14
15
16
17
18
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Katzel et al.,
2001 (50)
Longitudinal follow-up of male
athletes vs sedentary counterparts
42 athletes; baseline ¼ 63.4 6 1.0 y,
follow-up ¼ 71.4 6 1.1 y
47 sedentary men; baseline ¼ 61.1 6
0.9 y, follow-up ¼ 70.4 6 0.9 y
Modified Balke protocol:
Initial treadmill speed varied according to the individual, and was set to produce
approximately 70% of the subject’s peak HR (based on an initial screening test using the
Bruce treadmill protocol)
Treadmill elevation increased from 0% to 4% after 2 min, to 6% after 4 min, and
then by 2% every min until the subject reached voluntary exhaustion
Morey et al.,
1998 (4)
161 community-dwelling adults, ages
65–90 y (71.6 6 5.1 y)
Paterson et al.,
1999 (58)
4-min warm-up, speed 45.5 m/min (1.7 mph, 2.72 km/h, 0% grade)
298 subjects (152 men, 146 women),
Speed and grade increased in small increments in ramp-like manner
representing the non-institutionalized
Increases individually based, designed to elicit VO2 increases each min ranging from
population aged 55–85 y
Six 5-y age groups starting with age
1 to 3 ml/kg per min, with each subject’s test duration between 8 and 12 min
55; 35 men and women in each stratum
Sidney & Shephard, Men and women aged 60–83 y
1977 (59)
26 men (63.7 6 2.6 y)
29 women (63.4 6 3.6 y)
Subjects exercised to symptom-limited maximum
Minutes 1–3 speed 1.5 mph (2.4 km/h) at 0%, 2%, and 4% grade
Minutes 4–9 speed 2.0 mph (3.2 km/h) at 3%, 5%–9% grade
Minutes 10–13 speed 2.5 mph (4 km/h) at 8%, 10%, 12%, and 14% grade
Minutes 14–16 speed 3.0 mph (4.8 km/h) at 12%–14% grade
Minutes 17–20 speed 3.3 mph (5.3 km/h) at 14%, 16%, 18%, and 20% grade
Set speed of 2.5–3.5 mph (4.0–5.6 km/h)
Slope individually adjusted every 3 min to achieve an HR of 75%–85% of maximum
HR during the 9th min of exercise
At the beginning of the 10th min, slope increased to achieve an estimated 90%–100%
of the individual’s VO2max
Additional 1%–2% increases in slope every 2 min until subjective exhaustion, or the
presence of clinical indications to stop the test
Tanaka et al.,
1997 (38)
156 women (age 20–75 y): 84
endurance-trained runners including
16 subjects .60 y (64 6 1) and
72 sedentary subjects including
13 subjects .60 y (66 6 1)
6- to 10-min warm-up
Each subject ran or walked at a comfortable speed corresponding to 70%–80% of
age-predicted maximal HR
Grade increased 2.5% every 2 min until volitional exhaustion
Thomas et al.,
1987 (60)
224 men ages 55 and 68 y,
mean 62.3 y
Protocol 1: continuous, progressive test to maximum
Started at 1.33 m/s (3.0 mph, 4.80 km/h), grade 0% for 4 min
Grade increased 2.5% every 2 min until stopped, or until 20% grade attained
Speed then increased by 0.133 m/s (0.30 mph, 0.48 km/h) every 2 min until
maximal effort reached
Modified Protocol 1:
Started at 1.33 m/s (3.0 mph, 4.80 km/h), grade 0% for 4 min
Grade increased by 5% every 2 min up to 20%
Speed then increased by 0.267 m/s (0.6 mph, 0.96 km/h)
Protocol 2: discontinuous test
5–6 min at each of three submaximal workloads of 50%, 65%, and 85% of HR
reserve ([maximum HR resting HR] 3 60% þ resting HR)
HUGGETT ET AL.
60
Table 1. Maximal Treadmill Protocols for Older Adults (Continued)
Authors (Ref.)
Subjects
Protocol
Following the third stage and 3–5 min rest, grade increased
2.5% every 2 min up to 20%
Speed then increased 0.133 m/s (0.30 mph, 0.48 km/h) to exhaustion
Tonino & Driscoll,
1988 (61)
9 healthy older persons
(5 males, 4 females, aged
62–79 y, mean 70.4 y)
Continuous modified Balke protocol:
Four 3-min stages of 2 MET increments, followed by 2-min stages of 1 MET increments
until subjective fatigue
Note: HR ¼ heart rate; MET ¼ metabolic equivalent (3.5 ml O2/kg per min).
was determined using a treadmill and the modified Balke
protocol (51). In this procedure, the initial treadmill speed
varied according to the individual, and was set to produce
approximately 70% of the subject’s peak HR—determined
from an initial screening test on the treadmill at baseline by
using the Bruce treadmill protocol. Elevation of the
treadmill increased from 0% to 4% after 2 minutes, to 6%
after 4 minutes, and then by 2% every minute until the
subject reached voluntary exhaustion. Criteria for VO2max
included meeting two of the following three criteria: (a) HR
at maximal exercise .95% of age-predicted maximal HR,
(b) RER 1.10, and (c) increase in VO2 of ,0.2 l/min
during the final increase in workload (i.e., VO2max plateau).
The rate of decline of VO2max was significantly greater in
the endurance athletes as compared with the sedentary men,
particularly those athletes who were unable to maintain their
high level of training. The authors suggest that much of the
observed decline in VO2max in the athletes was due to
lifestyle changes rather than aging itself.
Morey and colleagues (4) studied 161 communitydwelling older adults between the ages of 65 and 90 years
(mean 71.6 6 5.1 years). They used a treadmill and exercised the subjects to a symptom-limited maximum. Their
protocol was as follows: minutes 1–3 at 1.5 mph (2.4
km/h) at 0%, 2%, and 4% grades; minutes 4–9 at 2.0 mph
(3.2 km/h) at 3%, 5%–9% grades; minutes 10–13 at 2.5 mph
(4 km/h) at 8%, 10%, 12%, and 14% grades; minutes 14–16
at 3.0 mph (4.8 km/h) at 12%–14% grades; and minutes 17–20
at 3.3 mph (5.3 km/h) at 14%, 16%, 18%, and 20%
grades. VO2peak was strongly associated with physical
function, as measured by a summary score combining scores
from five functional scales (p ¼ .004) including: (a) the
seven-item instrumental activities of daily living subscale of
the Older Americans Resources and Services (OARS) Multidimensional Functional Assessment questionnaire (52);
(b) five dichotomous questions of self-reported difficulty in
performing instrumental activities of daily living derived
from the Nagi study of disability (53); (c) a three-item selfreport of advanced activities of daily living (54); (d) the
Physical Functioning Scale of the Medical Outcomes Study
short form health survey SF-36PF (55); and (e) the Falls
Efficacy Scale (56,57).
Paterson and colleagues (58) used a noninstitutionalized
population of older adults between 55 and 85 years of age to
develop normative data on VO2max by 5-year increments.
Subjects were given a 4-minute adaptation period and warmup on a treadmill at a speed of 45.5 m/min (1.7 mph, 2.72
km/h) at a 0% grade. Following the warm-up period, speed
and grade were increased in small increments in a ramp-like
manner. The increases were individually based, and were
designed to elicit VO2 increases each minute ranging from 1
to 3 ml/kg per min, with each subject’s test duration between
8 and 12 minutes. Criteria for determining VO2max included:
(a) the occurrence of a 15-second plateau in VO2 despite
a continuing increase in power output; or (b) an RER .1.0
and an HR within 5 bpm of the age-specific maximal HR
(HRmax ¼ 220 bpm age). Results from this study indicate
that a linear model provides the best fit for age-related
declines in VO2max, although age explained at most 37% of
the variance across the age range.
Sidney and Shephard (59) compared submaximal cycle
ergometer and maximal treadmill tests in men and women
aged 60–83 years (men: n ¼ 26, 63.7 6 2.6 years; women,
n ¼ 29, 63.4 6 3.6 years). Their treadmill protocol had
Table 2. Maximal Cycle Ergometer Protocols for Older Adults
Authors (Ref.)
Cress & Meyer, 2003 (62)
Fairbarn et al., 1994 (64)
Jones et al., 1985 (65)
Poehlman & Danforth, 1991 (66)
Subjects
Protocol
Men and women (N ¼ 192; 76 6 7 y) from single-family
community dwellings or retirement communities with
multiple levels of care
Familiarization period
231 men and women equally divided within decades
between 20 and 80 y (no breakdown of specific ages
within decades provided)
100 healthy subjects (50 male and 50 female), selected to
provide an even distribution of age (15–71 y) and height
10 men and 10 women between 55 and 71 y
Initial power ouput at 16 or 32 W
Power increased by 16 W/min until subject reached
symptom-limited maximal power output
Initial power setting 16.3 W
Power increased by 16.3 W/min until a
symptom-limited power output reached
19 older adults (13 men, 6 women) (64 6 1.6 y)
Ramped test
Power output increased at a rate of 8–16 W/min
Initial workload for women: 25 W at 50 rpm
Initial workload for men: 50 W at 50 rpm
Initial workload sustained for 3 min
Increased by 25 W every 2 min until exhaustion or
until subjects unable to maintain 50 rpm
VO2max TESTING IN OLDER ADULTS
a fixed speed of 2.5–3.5 mph (4.0–5.6 km/h), and the slope
was individually adjusted every 3 minutes to achieve an HR
of 75%–85% of the maximum HR during the 9th minute of
exercise. At the beginning of the 10th minute, the slope was
increased to achieve an estimated 90%–100% of the
individual’s VO2max. Additional 1%–2% increases in slope
were made every 2 minutes until subjective exhaustion, or
the presence of clinical indications to stop the test. Results
from this study showed that only 75% of the subjects
reached the plateau definition proposed for younger subjects. This study also indicated that valid data cannot be
obtained without working subjects to exhaustion, as VO2max
was higher in subjects making a ‘‘good’’ exhausting effort
(evidenced by high lactate levels) than in subjects making
a ‘‘fair’’ effort (lower lactate levels).
Tanaka and colleagues (38) compared VO2max in 72
sedentary women to 84 endurance-trained women, aged
20–75 years (16 endurance-trained athletes .60 years, mean
64 6 1 years; 13 sedentary women .60 years, mean 66 6 1
years). Following a 6- to 10-minute warm-up period on the
treadmill, each subject continued to either run or walk on the
treadmill at a comfortable speed that elicited 70%–80% of
age-predicted maximal HR (equation to determine maximal
HR not provided). Grade was increased by 2.5% every
2 minutes until volitional exhaustion. The Borg Rating of
Perceived Exertion scale was used at the end of each stage.
Age alone accounted for 69% of the total variance in VO2max
in endurance-trained women and 57% in sedentary women.
The absolute rate of decline in VO2 max was greater in the
endurance-trained women (5.7 ml/kg/min/decade) compared with the sedentary women (3.2 ml/kg/min/decade;
p , .01), but the relative (%) rate of decline was similar
(9.7% vs 9.1% per decade). The greater absolute rate of
decline in VO2 max in endurance-trained women compared
with sedentary women was not associated with a greater rate
of decline in maximal HR, nor was it related to training
factors.
Thomas and colleagues (60) used three different treadmill
test protocols to assess VO2max in 224 men between 55 and
68 years of age (mean 62.3 years). Protocol 1 was
a continuous, progressive test starting at 1.33 m/s (3.0
mph, 4.80 km/h) and 0% grade for 4 minutes. The grade was
then increased by 2.5% every 2 minutes up to 20%, at which
point the speed was increased by 0.133 m/s (0.3 mph, 0.48
km/h) every 2 minutes until a maximal effort was reached. A
Modified Protocol 1 started at 1.33 m/s (3.0 mph, 4.8 km/h)
and 0% grade for 4 minutes, at which point the grade was
increased by 5% every 2 minutes up to 20%, then the speed
was increased by 0.267 m/s (0.6 mph, 0.96 km/h) until
exhaustion. Protocol 2 was a discontinuous test involving 5–
6 minutes at each of three submaximal workloads of 50%,
65%, and 85% of HR reserve ([maximum HRresting HR]3
60% þ resting HR). Following the third stage and 3–5
minutes of rest, the grade of the treadmill was increased by
2.5% every 2 minutes up to 20%, at which point the speed
was increased by 0.133 m/s (0.3 mph, 0.48 km/h) until
exhaustion. All subjects completed Protocol 1, and then were
randomly assigned to groups to repeat Protocol 1 (n ¼ 24),
complete Protocol 2 (n ¼ 145), or complete the Modified
Protocol 1 (n ¼ 38). In all protocols, a plateau in VO2 was
61
defined as an increase of 2 ml/kg per min with a change in
work rate. The results of this study indicate that reliability of
repeated VO2max measures in older men is acceptable
(r ¼ .67–.90), despite the finding that only one-third of the
men demonstrated a plateau in VO2. More specifically, the
correlation between the first and second tests for VO2max was
high for Protocol 1 (0.90) and between Protocol 1 and 2
(0.87), but was lower for the Modified Protocol 1 test (0.67).
Most of the older adults demonstrated a higher VO2max on
repeated testing using the same or similar test protocol,
suggesting that at least two maximal tests are required
to precisely quantify the cardiorespiratory capacity of
older men.
Tonino and Driscoll (61) studied nine healthy older adults
(5 men and 4 women, mean age 70.4 years). They used
a continuous modified Balke protocol on the treadmill,
whereby four 3-minute stages of 2-MET increments were
followed by 2-minute stages of 1-MET increments until the
subject reached subjective fatigue. This study also found that
VO2max is a reliable measure in older adults (test–retest
reliability: p , .05), whereas maximal duration of exercise,
submaximal HR, and submaximal VO2 demonstrated inconsistent results (p . .05). Unfortunately, correlation
coefficients and actual error are not reported. Contrary to the
results of Thomas and colleagues (60), Tonino and Driscoll
(61) found that VO2max was reproducible on repeat testing.
However, their results must be viewed with caution, as
Tonino and Driscoll (61) had a very small sample size of
nine persons.
Maximal Cycle Ergometer Tests
Cress and Meyer (62) collected VO2peak data on a sample
of 192 men and women (76 6 7 years, no gender breakdown
provided) using a cycle ergometer. Their protocol began with
a familiarization period followed by a ramp test with power
output increased at a rate of 8–16 W/min. No description was
provided as to the initial power output or criteria for the rate
of increase. The test was terminated when the participant
demonstrated signs and symptoms of fatigue or exercise
intolerance, electrocardiogram changes, or abnormal blood
pressure or respiratory responses. VO2peak data were reported so as to include data on individuals not meeting the
typical criteria for maximal effort. Cress and Meyer also used
two functional scales to measure functional limitation,
including the SF-36PF (55) and the Continuous-Scale
Physical Function Performance Test [CS-PFP] (63). Although Cress and Meyer used VO2peak data for their analysis,
they did note that 80.2% of their participants met two or
more of the criteria for reaching VO2max. Their criteria for
VO2max included: (a) an HRmax within 10 bpm of agepredicted maximum, (b) an RER .1.0, or (c) a rating of
perceived exertion of at least 18 on the Borg Rating of
Perceived Exertion Scale. They noted that by using only
VO2peak data physical reserve may have been underestimated for some subjects, but they felt that the data presented
may be more representative of the actual physical ability of
this population.
Fairbarn and colleagues (64) assessed 231 men and
women equally divided within the 6 decades between the
ages of 20 and 80 years. Using a cycle ergometer to test
62
HUGGETT ET AL.
VO2max, they set the initial power output either at 16 or 32
W. Regardless of initial output level, power was increased by
16 W/min until the participant reached a symptom-limited
maximal power output. The VO2max data were used to
develop prediction equations. Age alone accounted for 64%
of the variability in VO2max in women and 35% of the
variability in men. There was no information provided on the
tolerance of the protocol by the older versus the younger
participants.
Jones and coworkers (65) incorporated a sample of 50 men
and 50 women between the ages of 15 and 71 years (10 men
and 10 women between 55 and 71 years of age). A cycle
ergometer was used to measure VO2max with an initial power
setting of 16.3 W and an increase of 16.3 W/min until
a symptom-limited power output was reached. They discovered that the effect of leisure activity (measured by a
crude index of hours per week of exercise) was similar to the
effect of age alone on VO2max (r ¼ 0.47 in both instances).
Poehlman and Danforth (66) studied a small sample of
19 older adult participants (13 men and 6 women, mean
age 64 6 1.6 years). Initially, the workload was set at 25 W
for women and 50 W for men. After 3 minutes, workload
was increased by 25 W every 2 minutes until exhaustion, or
until subjects were no longer able to maintain a pedal speed
of 50 rpm. The purpose of this study was to investigate the
effects of endurance training on resting metabolic rate and
plasma norepinephrine kinetics in older adults. No information was provided as to the ability of the older adults to
tolerate the maximal testing protocol.
DISCUSSION
Several of the studies reviewed do not describe their
protocols in explicit detail, and only a select few provide
data on psychometric properties, thus making comparisons
difficult. Also of note is that four of the nine treadmill protocols described included either only men or only women as
subjects, making it difficult to compare results across test
protocols. This discussion will attempt to briefly summarize
similarities and differences between protocols as well as the
ability of subjects to satisfy predetermined criteria for
reaching VO2max.
Speed and Grade Increases
The studies by Foster and colleagues (36), Hollenberg
and associates (30), Morey and coworkers (4), and Paterson
and colleagues (58) all initiated their treadmill protocols at
a 0% grade with a speed of either 1.5 or 1.7 mph (2.40 or
2.72 km/h). Although the initial work rates were similar, the
subsequent ramp-like stages were quite varied, with some
increasing both speed and grade [Hollenberg et al. (30),
Morey et al. (4), and Paterson et al. (58)], whereas Foster
and colleagues (36) kept speed constant throughout and only
increased grade. A wide range in grade increases was
also found among the studies. For example: Morey and
colleagues (4), 1%–2% every minute; Hollenberg and
coworkers (30), 1% every 30 seconds after the initial 6
minutes; Foster and associates (36), 1% every 3 minutes;
and Tanaka and colleagues (38), 2.5% every 2 minutes.
Sidney and Shepherd (59) and Thomas and colleagues
(60) initiated their protocols at speeds .2.5 mph (4.0 km/h).
Whereas Sidney and Shepherd (59) maintained a constant
speed throughout the test and only increased grade, all three
protocols described by Thomas and colleagues (60) increased speed after a certain grade level was achieved.
Thomas and colleagues (60) compared three different test
protocols, two that incorporated differences in speed and
grade increases, and one discontinuous protocol. They
suggested that their Protocol 1, which involved a steady but
slow increase in both speed and grade, was the most appropriate choice, if one did not require data on submaximal
steady-state conditions, as would be available from
a discontinuous protocol (60). The study by Thomas and
colleagues (60) is unique in that the authors compared
different protocols using the same group of subjects; the
results thus provide insight on the appropriateness of the
protocols for older adults. However, the study sample
involved only men, and as such the results cannot be
generalized to the greater population of all older adults.
Individualization
Katzel and associates (50), Paterson and coworkers (58),
Sidney and Shephard (59), and Tanaka and colleagues (38)
all included individualized components in their protocols.
Paterson and colleagues (58) based individualization on
increases in VO2, whereas the other studies individualized the
increases in work rate based on percentage of maximum HR.
Attainment of VO2max Criteria and
Exercise Test Duration
A plateau in oxygen consumption occurred in 75% of test
sessions 1 and 2 and in 62% of test session 3 in the study by
Foster and colleagues (36). Their step increase protocol
resulted in longer tests (mean duration 20 minutes; range,
6–51 minutes) than did several of the other protocols. The
authors did comment that the testing protocol may have
been too lengthy for some individuals, resulting in decreased motivation both within a test, and following
repeated testing (36).
In the study by Hollenberg and associates (30), 32.9% of
women and 52.7% of men achieved an RER 1.10, which
was their criterion for having achieved maximal exercise.
The mean duration of exercise in this study was 10.0 6 4.0
minutes for women and 13.2 6 4.6 minutes for men.
Hollenberg and associates (30) and Morey colleagues (4)
describe VO2peak data, so as to include as many individuals
as possible, rather than excluding data based on the criteria
for maximal effort. Hollenberg and coworkers (30) found
that only 41% of women and 36% of men who exercised
for less than 8 minutes rated their maximal exercise effort
as ‘‘hard’’ to ‘‘very, very hard’’ (Borg score of 15–20)
compared with 71% and 84% of women and men,
respectively, who exercised for longer than 13 minutes; this
finding suggests that motivation influences VO2peak data.
The average time on the treadmill in the study by Morey
and colleagues (4) was 10.6 6 4.2 minutes. While Morey and
associates (4) did report on VO2peak data, they also noted
78.8% of all subjects met two of the three criteria for attaining
VO2max, although the three criteria were not described.
Paterson and coworkers (58) excluded 20.5% of their test
results from data analysis because the criteria for VO2max
VO2max TESTING IN OLDER ADULTS
were not met. The individualized ramp protocol in their
study allowed them to target a test termination between 8 and
12 minutes, which may have sustained subject motivation
(58). The individualized protocol, as well as the shorter test
duration, may have contributed to the finding that 79.5% of
their subjects were able to obtain the criteria for VO2max.
In the study by Sidney and Shephard (59), 69.2% of men
and 65.5% of women were able to achieve a plateau in VO2
of 0.2 ml/kg per min, while 96.2% of men and 72.4% of
women were able to achieve an RER 1.00. Most of their
subjects reached exhaustion after approximately 15 minutes
of exercise. In Protocol 1 in the study by Thomas and
colleagues (60), 33.6% of the 224 subjects reached a plateau
in oxygen consumption. VO2max was not significantly different between those exhibiting a levelling-off of VO2max
and those who did not reach a plateau, but the number of
subjects reaching a plateau did rise significantly with
repetition of the same or similar test protocol.
Katzel and colleagues (50) noted that all VO2max tests
fulfilled at least two of the three following criteria: (a) the
HR at maximal exercise was .95% of the age-predicted
maximal HR, (b) the RER was 1.10, and (c) the VO2max
reached a plateau during the final stage of exercise—that is,
the increase in VO2 was ,0.2 l/min during the final increase
in work rate.
Tanaka and associates (38) had similarly strict criteria for
attainment of VO2max in their study, and reported that all
subjects fulfilled at least three of these four criteria: (a) a
plateau in VO2 with increasing exercise intensity, (b) RER 1.15, (c) achievement of age-predicted maximal HR (610
bpm), and (d) rating of perceived exertion 18 units.
Treadmill tests lasted between 8 and 12 minutes in this study.
Although a plateau in VO2 has long been considered the
classical requirement for attaining maximal cardiorespiratory effort, there has been considerable disagreement with
respect to the definition and criteria for a plateau (67). The
results of this review suggest that many older adults are
unable to reach a plateau in VO2. This could be related to the
fact that the criteria for a plateau in VO2 have been defined
using data from younger adults. Of particular note is the
criterion for maximum HR, defined in most studies as 220 age. Tanaka and coworkers (68) performed both a metaanalysis and a laboratory-based study investigating HRmax in
older adults. Their findings suggest the formula [208 (0.7 3
age)] is a more acceptable equation for both older men and
women and that the use of the traditional equation (220 age) may in fact underestimate the actual level of physical
stress imposed during exercise testing. It would be interesting to evaluate the effect of this change in criteria for
attaining VO2max on the previously described protocols to
determine if a greater percentage of older adults met the
new criteria.
In addition, there is sufficient evidence available to
suggest that reaching a plateau is a highly variable outcome,
even in younger adults (67,69,70). Myers and associates
(67,69) found significant variability in the slope of change in
VO2 during either a constant or progressive change in
external work, regardless of the sampling interval used; this
finding suggests that the plateau concept has limitations for
general application during standard exercise testing. As
63
previously noted, Thomas and colleagues (60) found that
reliability of repeated VO2max measures in older men is
acceptable (r ¼ .67–.90), despite the finding that only onethird of the men demonstrated a plateau in VO2. However,
they also reported that reliability was higher for those
individuals reaching a plateau in two of their three protocols
(r ¼ 0.92 vs 0.82, r ¼ 0.86 vs 0.60) (55). Recently, Day and
coworkers (70), using several different protocols, specifically investigated whether a VO2 plateau was a consistent
outcome of maximal aerobic exercise. They discovered
a plateau in the actual VO2 response is not a necessary consequence of incremental exercise testing. As well, in constant load tests, the peak value attained was not different
from the plateau obtained in the plot of VO2 versus work
rate. Therefore, they suggest that the VO2peak attained on
a maximum effort incremental test is likely to be a valid
index of VO2max, even though there may be no evidence of
a plateau in the data themselves.
Cycle Ergometer Tests
Of the three studies that included VO2max measurement of
older adults using cycle ergometers, none described the
ability of the older adults to tolerate the test. In their study,
Cress and Meyer (62) did not describe their protocol in
detail, and did not provide the initial power output. They did,
however, report that 80.2% of their subjects met two or more
criteria for attaining VO2max (62). Both Fairbarn and
colleagues (64) and Jones and coworkers (65) used an
initial power output of 16 W [although an undisclosed
number of subjects in the study by Fairbarn and associates
(64) started their test at 32 W], with an increase of 16 W/min.
Subjects exercised to a symptom-limited maximal power
output, with no other indicators that maximal aerobic power
was reached. The subjects in the Poehlman and Danforth
study (66) started with a much higher workload (25 W for
women and 50 W for men) and increased by a larger
workload (25 W every 2 minutes). Information on individualization, attainment of VO2max criteria, and exercise
test duration was not provided in the literature for the cycle
ergometer tests.
Functional Cut Point
Morey and colleagues (4), Paterson and coworkers (58),
and Cress and Meyer (62) all described a VO2 cut point for
optimal functional performance. Morey and colleagues (4)
described the optimal cut point between low physical function (requiring assistance with activities of daily living) and
high physical function (independent living) to be 18.3 ml/kg
per min (p , .0001), although no evidence of a levelling-off,
indicative of a true threshold distinguishing individuals with
low from those with high physical function, was reported.
Paterson and associates (58) reported the minimum level of
VO2max that corresponded to a fully independent life at age
85 in their study sample to be 17.7 ml/kg per min for men
and 15.4 ml/kg per min for women. The major finding of the
Cress and Meyer study (62) was the existence of a threshold
of aerobic capacity (20 ml/kg per min) below which physical
function was most affected by low fitness levels. All three of
these studies used a ramp-like protocol, with Morey and
colleagues (4) and Paterson and coworkers (58) using the
64
HUGGETT ET AL.
treadmill and Cress and Meyer (62) using the cycle ergometer for testing VO2max. Both Morey and associates (4) and
Cress and Meyer (62) used the 36-item SF-36PF (55) as one
of the measures of functional limitation in their samples.
Subjects in the study by Paterson and colleagues (58) were
all living independently in the community at the time of
testing. It is interesting to note that the study by Cress and
Meyer (62), using the cycle ergometer, had a higher value
for the threshold of aerobic capacity, despite the fact that
VO2max is typically lower using a cycle ergometer than
a treadmill (9–12). With 80.2% of individuals able to meet
the criteria for VO2max in the study by Cress and Meyer (62),
as compared to 74% of the individuals in the study by
Paterson and colleagues (58), it might be possible that the
individuals in the study by Cress and Meyer (62) were
a higher functioning group. Both Morey and associates (4)
and Cress and Meyer (62) used VO2peak for their data
analysis.
Clinical Use of Exercise Tests
The treadmill has been lauded for its use as a testing
device because of the familiarity of subjects with walking,
and for the purpose of data comparison, because there is
a great deal more research using the treadmill than using any
other type of equipment (36). As well, many studies have
found that VO2max is lower using a cycle ergometer than
a treadmill (7,10,71). However, the difference in VO2max
noted between treadmill and cycle ergometer testing may
be exaggerated in older adults, because they are forced to
use muscle groups they are unaccustomed to using, during
a form of exercise with which they are unfamiliar (16). The
lack of well-described cycle ergometer protocols for older
adults, as well as the lack of descriptive data provided on
tolerance to the protocols, does not facilitate their use in
a clinical setting.
However, there are distinct advantages to using a cycle
ergometer, including greater ease of obtaining blood
pressure, electrocardiogram, and other physiological measures; relative expense of a cycle ergometer (typically much
less than a motorized treadmill); and practical considerations
(a cycle ergometer occupies less space than a treadmill, is
easier to move, and does not necessarily require electricity)
(72). As well, there is a safety concern for older individuals
on a treadmill, with respect to balance (72). In some
instances, frail older adults may not be able to ambulate
safely at the lowest speed possible on the treadmill, typically
1.0 mph (1.6 km/h) (62). The many practical advantages of
the bicycle ergometer certainly justify further research using
this modality for VO2max testing in older adults.
Another possible avenue for future research addressing
VO2max testing in older adults is the investigation of an allextremity ergometer, such as a recumbent cross-trainer or an
elliptical trainer. Hass and coworkers (73) compared nine
non-exercising control subjects with 17 individuals who
participated in a thrice weekly progressive exercise program
for 12 weeks using a total body recumbent stepper (mean
age ¼ 48.4 6 6.4 years). The researchers found a significant
18% increase in VO2max in the exercising group with no
significant change in the control group. The use of an allextremity ergometer might be particularly useful in the older
adult population to maximize the muscle mass involved in
exercise and to allow for compensations for either unilateral
or bilateral extremity weakness or pathology (74).
Buchfuhrer and associates (75) suggested work rate
increments should be selected appropriately to attain VO2max
in approximately 10 minutes (62 min) with all exercise
stress tests. Longer tests not only waste time and supply no
additional information (76), but also risk a subject’s inability
to achieve VO2max criteria due to a decrease in motivation,
increase in discomfort (complaints of low back pain on the
treadmill and seat discomfort on the cycle ergometer),
increase in body temperature, greater dehydration, or
ventilatory muscle fatigue (75). Prolonged stage durations
and/or rapid stage increases, typically seen in some of the
protocols for younger individuals, may cause muscles to
fatigue prior to the older subject obtaining a plateau in VO2
(75,77). The protocols of Foster and colleagues (36) and
Sidney and Shephard (59), having average test durations of
20 minutes and 15 minutes, respectively, may have yielded
a lower percentage of individuals attaining VO2max criteria
than if the duration of exercise had been shorter.
Prior to developing their test protocol, Foster and colleagues (36) conducted a pilot study on older women and
determined that a walking speed of 4.8 km/h at a 0% grade
produced a negative psychological response. Although no
further information regarding the exact nature of the response was provided, they did note that arrhythmias and HR
near age-predicted maximum were elicited in apparently
healthy individuals at the above-mentioned speed, even with
a prior warm-up period. Although the limited details and the
small number of participants in this study provide only
a weak basis for a recommendation, these data, along with
the concern for balance deficiencies and lack of familiarity
with treadmill ambulation, may support the use of the
protocols with slower initial speeds on the treadmill.
Limitations of the Critical Review
This review is limited to published data in the English
language and is focused solely on studies of healthy individuals. However, as previously noted, many older adults
have at least one, if not multiple, chronic medical conditions
(27). Smaller work rate increases and a lower starting point
may be particularly necessary for individuals with one or
more health conditions. Future investigations could benefit
from review of the available literature on VO2max testing of
individuals with various medical conditions.
Conclusion
There is extensive literature available on VO2max testing in
younger adults; however, this review has indicated that the
research on VO2max testing in individuals older than 65 years
of age is limited. Additionally, the literature available on
VO2max testing in healthy older adults is flawed by a lack of
detail with respect to protocol description as well as a lack of
data on psychometric properties. The study by Thomas and
coworkers (60) is the only one to compare three different
VO2max testing protocols using the same group of subjects.
Their results suggest that a continuous ramp-like protocol
with small increases in both speed and grade is perhaps most
appropriate for healthy older men. This study provides
VO2max TESTING IN OLDER ADULTS
a strong basis for comparison of the appropriateness of
different test protocols, however, there is limited generalizability to the greater population of older adults due to the
exclusion of women. Based on this critical review, no
specific recommendations could be made regarding an
optimal protocol or modality for VO2max testing in healthy
older adults.
There is a pressing need for refinement of the few existing
protocols for testing aerobic capacity in the older adult
population, as well as the development of new protocols
specifically applicable to older adults. Future investigation of
studies comparing different testing modalities using similar
protocols as well as comparing different protocols in the
same group of older adults would be beneficial. This review
was limited to describing VO2max testing protocols in healthy
older adults. Further review of the literature is required to
determine the appropriateness of maximal exercise testing
protocols in older adults with various medical conditions.
Finally, there is a need for agreement on whether the
criteria for reaching VO2max should be redefined for older
adults, and if the most appropriate test, for successful
fulfillment of the criteria by all subjects, still needs to be
developed. Perhaps a different definition of the VO2max
criteria, such as using the [208 (0.7 3 age)] equation for
maximum HR described by Tanaka and associates (68),
would allow more individuals to meet the criteria, or
perhaps VO2peak data provide sufficient information for our
current purposes in using maximal aerobic capacity data.
ACKNOWLEDGMENTS
We acknowledge with thanks financial support provided by the Ontario
Provincial Rehabilitation Program and the Physiotherapy Foundation
of Canada.
Address correspondence to Dr. Tom Overend, School of Physical
Therapy, University of Western Ontario, London, Ontario, Canada
N6G 1H1. E-mail: [email protected]
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Received December 5, 2003
Accepted March 11, 2004
Decision Editor: John E. Morley, MB, BCh