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WOrkOuT PrOgrAm OvErviEW
the nautilus® Fitness test
Understanding Sub-maximal Exercise Testing
Before using the Nautilus TreadClimber
®
TC916 for sub-maximal exercise testing, it
should be noted that all sub-maximal tests make several assumptions:
• That a steady-state heart rate is obtained for each exercise workload.
• That a linear relationship exists between heart rate, oxygen uptake and
workload.
• That the maximal heart rate for a given age is uniform.
• That the mechanical efficiency of the physical activity performed (i.e., oxygen
uptake at a given workload) is the same for everyone.
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
2 max
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 heart rate
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 heart rates 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 heart rates differ by less than five beats per
minute.
It is also important that the sub-maximal heart rates obtained be between 115
and 150 beats per minute, because it is within this heart rate range that a linear
relationship tends to exist between heart rate and oxygen uptake or workload for
most adults. When the heart rate is less than 115, many external factors (e.g.,
talking, laughing, apprehension, etc.) can greatly influence heart rate. Once the heart
rate reaches a level between 115 and 150, external factors no longer influence heart
rate, and a linear relationship exists. As the heart rate rises above 150, the heart-
rate/oxygen uptake relationship becomes curvilinear.
The third assumption involves maximal heart rate. Maximal heart rate is the greatest
heart rate that can be measured when an individual is exercising to the point of
volitional fatigue (i.e., exhaustion) during a graded exercise test. The TreadClimber
®
TC916 uses the most current published equation developed to estimate the average
maximal heart rate as follows:
• Maximal heart rate = 215 minus (0.75 x age)
