Stairmaster 4200 PT FREECLIMBER 4400/4600 PT/CL CONSOLE, Page, minus 0.5 x age high estimate

FREECLIMBER 4400/4600 PT/CL CONSOLE

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 rela- tionship 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 exercis- ing to the point of volitional fatigue (i.e., exhaustion) during a graded exercise test. Several equations have been developed to estimate the average maximal heart rate for humans:

•	Maximal heart rate	=	220 minus age (low estimate)
•	Maximal heart rate	=	210 minus [0.5 x age] (high estimate)
•	Maximal heart rate	=	226 minus age (estimate for older
	individuals)

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 VO2 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 aver- age oxygen consumption associated with a given workload may vary signifi- cantly from one person to another. Thus, VO2 max predicted by submaximal exer- cise tests tends to be overestimated for those who are mechanically efficient and underestimated for those who are inefficient.

The point to remember is that submaximal 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

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