A simple formula for the estimation of maximal oxygen intake during cycle ergometry.

Exercise prescription has traditionally been based on the heart rate/work rate relationship. Many post-myocardial (MI) patients are now taking medications such as beta-blockers that alter this relationship, necessitating an alternative method for exercise prescription. The directly measured maximal oxygen intake (VO2max) is not substantially affected by such medications, but direct determinations of VO2max are time consuming, costly, and vulnerable to both local muscle weakness and poor motivation. We have therefore re-examined the relationship between work rate and maximal oxygen intake in order to derive a simple formula which will give an indirect estimate of the latter. Our results, obtained on 28 patients receiving beta-blockers, 13 receiving calcium channel blockers, 10 receiving combined therapy, and 49 who received neither treatment, indicate that the peak oxygen intake can be estimated accurately, using the expression VO2max.ml.min-1 = 2W, where W is the peak power output, measured in kp.m.min-1, or 12.3 W, where W is the peak power output in Watts.