Stairmaster StepMill SM916 Assembly Manual page 41

Operation
It should be kept in mind that any one or all of the above mentioned assumptions
may not be met during a sub-maximal exercise test. If for any reason one of the
assumptions is not met, then errors in predicting VO (Maximum volume of
2 MAX
oxygen consumed per unit of time) will occur.
Unfortunately, it is often quite difficult to meet all of the requirements for the four
listed assumptions. For example, exercising at a given workload for only a few
minutes can involve an insufficient amount of time for many individuals to achieve
a true steady-state. To ensure that a steady-state has been achieved, the HR
should be measured after two minutes of exercise at a given workload and again
after the third minute of exercise at that workload. These two HR's should then
be compared. If a difference of more than five beats per minute between the
two is found, the subject should continue to exercise at one-minute intervals at
the same workload until two successive HR's differ by less than five beats per
minute.
It is also important that the sub-maximal HR obtained be between 115 and 150
BPM, because it is within this HR range that a linear relationship tends to exist
between HR and oxygen uptake or workload for most adults. When the HR is less
than 115, many external factors (e.g. talking, laughing, apprehension, etc.) can
greatly influence HR. Once the HR reaches a level between 115 and 150, external
factors no longer influence HR, and a linear relationship exists. As the HR rises
above 150, the HR/oxygen uptake relationship becomes curvilinear.
The third assumption involves maximal HR. Maximal HR is the greatest HR that
can be measured when an individual is exercising to the point of volitional fatigue
epM ill
(i.e. exhaustion) during a graded exercise test. The St SM916 uses the
®
most current published equation developed to estimate the average maximal HR
as follows:
Max Heart Rate = 215 – (Age * .75)
Maximal HR can, however, vary greatly among different individuals of the same
age. One standard deviation is ±12 BPM, which means that two-thirds of the
population varies an average of plus or minus 12 heart beats from the average
given by a prediction equation. If an individual's age-predicted maximal HR is
higher than that person's true maximal HR, then his/her estimated VO will be
2 MAX
an overestimation of the correct or actual value.
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Owner's Manual