Borg's scale is an accepted tool in both assessment and prescription of exercise. Presently, no Philippine study reported its use as proxy indicator of heart rate. Secondary data were utilized from a study that used perceived exertion and heart rate as variables. Eight trained, apparently healthy, male cyclists were asked to perform a braked cycle ergometer test. A five-minute warm-up with an exercise intensity of 75-100 watts maintaining 90-100 revolutions per minute was employed increasing it by 50 watts after every five minutes until termination getting the heart rate and perceived exertion for each stage. Heart rate increased as the rate of perceived exertion went up. A positive significant correlation between the two variables using the Pearson's analysis was observed. The predicted formula for heart rate using the fitted line plot is hr = 116.3 + 7.5 (rpe). Scale set >/ 5 for positive exertion and < 5 for negative exertion showed a sensitivity of 0.83 and a specified of 0.91 with a positive predictive value of 0.90. Borg's scale can approximate the heart rate to a certain extent during exercise. More participants of different physical activities should be included to improve the predictive ability of the derived formula.