Effects of different training intensities on oxygen intake were determined in this study. Sixteen male subjects aged 16-18 were randomly assigned to one of three training groups or a control group. The training groups trained 3 days per week on bicycle ergometers at different intensities (85 percent, 75 percent, or 65 percent of heart rate maximum) with all groups doing the same total mechanical work (12,000 KPM per training session). Analysis of covariance revealed a significant difference between the groups. Significant differences were found between both the 85 percent and 75 percent groups and the control. No significant differences were found between the 65 percent group and the control or between the 75 percent and the 85 percent group. Within the limitations of the study, it was concluded that when comparing between training intensities while holding mechanical work constant, it is necessary to work at a minimum of 75 percent of heart rate maximum to elicit significant changes in oxygen intake maximum. (Author)