Fitness experts recommend trying to achieve and maintain exercise pulse rate in a specific range known as one’s target heart rate when exercising. This heart rate range varies among individuals, but can be calculated utilizing a formula known as the Karvonen method. In general, the formula takes into account one's age, maximum heart rate, and resting heart rate to calculate the most effective exercise pulse rate.
To determine exercise heart rate using the Karvonen method, first determine an intensity range. Unfit individuals and novice exercisers will want to start with 50% intensity, while more fit or experienced exercisers may want to work at 65% intensity or higher. The Karvonen method takes into account both the low end of the intensity range and the high end, which is typically 85-90%.
Taking a sample intensity range of 50-85%, the range in which one wants to maintain the exercise pulse rate for the duration of the workout, the Karvonen formula can be calculated as follows: Target heart rate (THR)= ((MaxHR - RHR) x Intensity %) + RHR. Maximum heart rate, or what is considered to be the maximum safe heart rate during exercise, can be determined by subtracting one’s age from 220, so a 30-year-old would have a MaxHR of 190. Resting heart rate can be measured by taking one’s pulse and counting the number of beats for one minute, ideally when one first awakens in the morning.
If the sample individual has a MaxHR of 190, an RHR of 70, and a desired intensity range of 60-85%, then that person’s exercise pulse rate can be calculated using the Karvonen method. First, the low end of the range must be determined: THR= ((190-70) x .60) + 70 = 142 beats per minute. Next, the high end: THR= ((190 – 70) x .85) + 70 = 172. Therefore, that person’s exercise pulse rate should be maintained between 142 and 172 beats per minute during exercise to achieve improvements in cardiovascular fitness.
Maintaining a target heart rate ensures the exercise performed will bring about improvements to cardiovascular health. It also is an indicator of intensity that can predict the effectiveness of a particular form of exercise. This can help assess its value as a fat-burning method.
During exercise, increased demands for oxygen by the muscles means that the heart has to beat more rapidly to deliver a larger volume of oxygen via the blood to these working muscles, which will utilize it for energy production. Oxygen is drawn into the lungs, where blood pumped out of the heart stops by to pick it up before being pumped back through the heart and out to the body for delivery. To transport a larger volume of oxygen over a set period of time — during a 30-minute cardio workout, for instance — heart rate must increase from its resting rate to its exercise pulse rate.
An indicator of cardiovascular fitness is the volume of oxygen that can be carried by the quantity of blood that exits the heart with each beat. A fit person will be more efficient at taking up oxygen than an unfit person, meaning that that individual’s heart will not need to beat as many times per minute to deliver the amount of oxygen that the body requires. The resting heart rate (RHR) will be lower, typically under 70 beats per minute in a fit individual, and the exercise pulse rate, which corresponds with the resting heart rate, will be lower as well. Training the cardiovascular system by exercising within one’s target heart rate range will make it more efficient over time and will lower the resting heart rate.