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The Use of Submaximal Cycle Ergometer Tests to Predict VO2 max
Gregory Levin
Edith Cowan University
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The Use of Submaximal Cycle Ergometer Tests to Predict VO2 max
One of the best and most useful physiological measurements that an athlete can
know is their maximal oxygen uptake. More commonly known as VO2, it is defined
by Wilmore and Costill (1999, p. 697) as “the maximal capacity for oxygen
consumption by the body during maximal exertion.” There are two different ways of
expressing VO2 max. They are the absolute VO2 max, expressed in litres per minute
(l/min) and the relative VO2 max expressed in millilitres per kilogram per minute
(ml/kg/min) (Wilmore & Costill, p. 141). To obtain the most accurate VO2 max value,
testing should be performed in a laboratory with the use of special gas analysis
equipment (Rushall & Pyke, 1990). However, for a number of reasons VO2 max is not
measured directly, but rather predicted by examining results from submaximal tests
(Heyward, 1991; Kasch, 1984; Rushall & Pyke, 1990).
There are two submaximal tests that are very commonly used. They are the
Astrand test and a physical work capacity or PWC test (Gore, Booth, Bauman &
Owen, 1999; Rushall & Pyke, 1990). Both of these tests are performed on a cycle
ergometer, and are used by athletes as well as non-athletes (Grant, Joseph &
Campagna, 1999).
Both the Astrand test and the PWC test use a relationship between workload and
heart rate in order to predict VO2 max (Adams, 1994). There are a few different PWC
tests. The one that is looked at in this paper is the PWC75%, which is an updated
version of the older PWC150 and PWC170 tests. The Astrand test uses only one
constant workload for the duration of the test (Grant, Joseph & Campagna, 1999)
whereas McConnell & Sinning (1980) describe that PWC tests use increasing
workloads throughout the test.
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As mentioned previously, the heart rate response to submaximal work is used to
predict VO2 max (Heyward, 1991). Wilmore and Costill (1999) define heart rate as
“the amount of work that the heart must do to meet the demands of the body.” Heart
rates increase as the exercise intensity increases and can reach a predicted maximum
of 220 beats per minute minus the athlete’s age (Pfitzinger & Freedson, 1998). Due to
the assumed relationship between heart rate and VO2 max McConnell & Sinning
(1980) explain that a steady state heart rate must be reached at each different
workload of these two tests.
This paper will compare the results of VO2 max obtained by football and soccer
players using both the Astrand and PWC75% tests.
Method
Participants
PWC75
A total of 12 participants undertook the PWC75 test. Of the 12, six were soccer
players and six were football players. Participants’ age ranged from 17 to 22 years
and all were male. Participants were students from Edith Cowan University that were
studying a Bachelor of Sports Science. Participation was voluntary and if requested
the test could be stopped at any time.
Astrand
A total of 17 participants undertook the Astrand test. Of the 17, seven were
soccer players and ten were football players. Participants’ age ranged from 18 to 24
years and all were male. Participants were students from Edith Cowan University that
were studying a Bachelor of Sports Science. Participation was voluntary and if
requested the test could be stopped at any time.
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Materials
PWC75
Equipment used to conduct the test included a Monark cycle ergometer, a Polar
A3 heart rate monitor, a stopwatch, recording sheets, and a calculator.
Astrand
Equipment used to conduct the test included a Repco fitness ergometer, Repco
disk, a Polar A3 heart rate monitor, a stopwatch, recording sheets, and a calculator.
Procedure
Allow the participant to put on the heart rate transmitter and monitor and ensure
that they are in working order and are receiving a reading. At the same time, adjust
the cycle ergometer so that the participant will sit comfortably and will be able to ride
freely. Obtain background information about the participant, including their exercise
history. Record the resting heart rate before beginning testing.
PWC75
Calculate the age predicted heart rate maximum. Using the results, determine
what the heart rate will be at 55%, 65% and 75% of max. According to the
participants exercise history select an initial workload. The participant begins the test
and the heart rate is recorded at the end of each minute. The rates recorded for the
second and third minute should be no more than 3bpm different. If the difference is
larger than 3bpm the participant must continue cycling for an additional amount of
time until the heart rate levels off and the difference between two consecutive minutes
is less than bpm. Once this is achieved the participant rests for a period of one minute
but continues to cycle at a decreased intensity. During the rest period a new workload
is calculated at which the second segment of the test will take place. After the minute
break the participant resumes cycling at the new workload. The second segment
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continues the same way as the first. In the rest period following the second segment a
new workload is calculated again for the third segment. The same steps are repeated
for this third segment. If the steady state heart rate measured during the third segment
is below 75% of heart rate max, then a fourth segment should be completed. At the
end of the test the participant should cool down by cycling at a decreased intensity
until their heart rate is below 60% of heart rate max.
Astrand
According to the participants exercise history select a workload at which the test
will be performed. This workload should ensure that the participant’s heart rate
reaches 130 – 150 bpm. Instruct the participant to pedal at the desired workload
recording the heart rate at the end of every minute. If at the end of the second minute
the heart rate is below 130bpm the test is terminated and the participant is allowed
time to recover. After a few minutes the test should re-commence at a higher
intensity. Continue recording the heart rate for six minutes. At the end of the sixth
minute check to see if a steady state heart rate has been achieved. This means that the
recorded rate at the end of the 5th and 6th minute are less then 5bpm apart. If no steady
state has occurred the participant must continue to cycle until this level is reached. At
the end of the minute in which steady state heart rate is reached the participant begins
a cool down, cycling at a much lower intensity. Average the heart rate for the last two
minutes of the test and use a Repco disk to calculate the predicted VO2 maximum.
Results
Both tests indicate that the VO2 max expressed in ml/kg/min is higher for soccer
players than it is for football players. However expressed in l/min the VO2 max of
football players, who took did the PWC test, was slightly greater than that of soccer
players. Reasons for the much larger differences in VO2 max expressed in ml/kg/min
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can be attributed to the average weight of the groups. The soccer group that took the
PWC test had an average weight of 72.25kg compared to 82.4kg average of the
football group taking the same test. For the Astrand test, average weights were 71.5kg
VO2max (ml/kg/min)
and 79.4kg for soccer and football groups respectively.
56
52
48
44
40
36
32
Astrand Footy
Astrand
PWC Soccer
Soccer
Test and Sport
PWC Footy
Figure 1.VO2max expressed in ml/kg/min of football and soccer players
VO2 (l/min)
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3.9
3.8
3.7
3.6
3.5
3.4
Astrand Footy Astrand Soccer PWC Soccer
PWC Footy
Test and Sport
Figure 2. VO2max expressed in l/min of footbal and soccer players
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Discussion
The results suggest that there is variability between the figures that are obtained
using the two tests, but the exact amount is unknown because the tests were taken by
different samples. As for the difference in absolute and relative VO2 max, that can be
related to the differences in body weight between all the groups involved
(Hutchinson, Cureton, & Outz, 1991).
According to Gore and Edwards (1992) the norm value for VO2max for men
aged 18-29 years ranges from 30.7ml.kg-1.min-1 to 66.57ml.kg-1.min-1. More
specifically Wilmore and Costill (1999) suggest that males footballers between 20 and
36 years of age should have a VO2 max of 42-60ml/kg/min and that males soccer
players between 22 and 28 years should have a VO2 max of 54-64ml/kg/min.
Wilmore and Costill provide norms that match the results of this test insofar as they
have suggested that soccer players’ VO2 max is higher than that of football players’.
Results from this study were generally within these ranges except for the soccer
players who took the Astrand test. However Wilmore and Costill have given a range
suited for 22 to 28 year olds and all players in the Astrand soccer group were 21 years
old or younger.
It is important to remember that when a submaximal test is performed VO2 max
is only a predicted figure. Grant, Joseph and Campagna (1999) mention that the
correlation of results for the Astrand test is only 0.40 for men but it is much higher,
0.92, for women. Not only are results different between submaximal tests and
maximal tests, results also differ according to what type of test is used. McArdle &
Magel (1969) reported that in a study they conducted VO2 max levels were between
0.5-21% lower when testing on a cycle ergometer than when the same subject was
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tested on a treadmill. In their study, only two of 23 participants attained a higher VO2
max on the bike.
The fact that the values attained via this form of testing are not always very
accurate does not mean that such tests should not be conducted. The American
College of Sports Medicine suggest that submaximal testing is beneficial and that it
can be used as a way of measuring fitness levels and changes in resulting from
training (ASCM, 1986). Gore, Booth, Bauman and Owen (1999) explain that this
fitness levels can be measured because VO2 max improves with training. However
because the PWC75 test uses interpolation rather that extrapolation, which was used
with the older PWC tests, it may be more accurate and should perhaps be the
preferred choice (Gore, Booth, Bauman & Owen, 1999). Unfortunately this test
(PWC75) is also relatively new and there is insufficient evidence to prove these
statements.
There are also several disadvantages and flaws associated with these two tests.
Some disadvantages are the fact that only a few people, often only one person, can be
tested in a single session and also performing the test is costly due to the equipment
needed (Adams, 1994). Another disadvantage that has already been mentioned is the
fact that results may be fairly inaccurate and that people who are not familiar with
cycling usually attain lower scores (McArdle & Magel, 1969).
Flaws with these tests are that a relationship between heart rate, oxygen uptake,
and work is assumed (Heyward, 1991; Grant, Joseph & Campagna, 1999). Although
this is generally true, it is not always the case. Also the heart rate max is not known
and the age predicted method can vary considerably (Heyward, 1991; Grant, Joseph &
Campagna, 1999). Both, Adams (1994) and Grant, Joseph and Campagna (1999) also
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mention that with this form of testing VO2 max values are generally overvalued for
trained athletes and undervalued for untrained people.
Despite their flaws and disadvantages these two tests are still valuable
physiological tests. Although their predictions VO2 max are not always correct they
are often close to the actual VO2 max. These submaximal tests are also easier to
perform. This allows people who would not be able to complete a max test the
opportunity to gain some form of VO2 max reading. An example of such people is the
elderly. Submaximal tests are also less expensive to conduct than are maximal tests.
Gore, Booth, Bauman, and Owen (1999) sum up the use of submaximal testing
mentioning that they are favoured but they should not be used to as a replacement for
maximal VO2 testing.
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