VO2 Reserve vs. Heart Rate Reserve During Moderate Intensity Treadmill Exercise.

VO2 and heart rate (HR) are widely used when determining appropriate training intensities for clinical, healthy, and athletic populations. It has been shown that if the % reserve (%R) is used, rather than % of max, HR and VO2 can be used interchangeably to accurately prescribe exercise intensities. Thus, heart rate reserve (HRR) can be prescribed if VO2 reserve (VO2R) is known. Therefore, the purpose of this study was to compare VO2 R and HRR during moderate intensity exercise (50%R). Physically active college students performed a maximal treadmill test to exhaustion. During which VO2 and HR were monitored to determine max values. Upon completion of the maximal test, calculations were made to determine the % grade expected to yield approximately 50% of the subjects VO2R. Subjects then returned to complete the submaximal test (50%R) at least two days later. The %VO2R and %HRR were calculated and compared to the predicted value as well as to each other. Statistical analysis revealed that VO2 at 50%R was significantly greater than the actual VO2 achieved, p < .001. Conversely, the mean predicted HR at 50%R was significantly less than the actual HR achieved, p < .001. In conclusion, this study indicated that VO2 could be more accurately predicted than HR during moderate intensity exercise. The weak correlation between VO2R and HRR indicates that caution should be used when relying on a HR to determine VO2.