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21
MORE WORKOUTS: FIT TEST PROGRAM
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
T9.14 treadmill 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)
Maximal heart rate 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
heart rate is higher than that person’s true maximal heart rate, then his/her
estimated VO
2 max will be an overestimation of the correct or actual value.
The final assumption addresses the issue of mechanical efficiency. Oxygen
uptake at any given work rate can vary by approximately 15% between
different individuals. Therefore, individuals vary in the amount of oxygen they
require to perform a certain exercise workload. Some individuals are more
efficient at performing a given task than others. As a result, the average
oxygen consumption associated with a given workload may vary significantly
from one person to another. Thus, VO
2 max predicted by sub-maximal exercise
tests tends to be overestimated for those who are mechanically efficient and
underestimated for those who are inefficient.
The point to remember is that sub-maximal exercise testing, though not as
precise as maximal exercise testing, is not without advantages. For example,
the results of such testing can provide a fairly accurate reflection of an
individual’s fitness status without the cost, risk, effort (on the part of the
subject) and time involved in max testing. If an individual is given repeated
sub-maximal exercise tests and that person’s heart rate response to a fixed
workload is found to decrease over time, it is reasonably safe to conclude that
the individual has made improvements in aerobic (cardiorespiratory) fitness,
irrespective of the accuracy of the VO
2 max prediction.
FIT TEST PROGRAM