It is sometimes difficult to gauge if you are exercising too hard or not hard enough. The two most commonly used methods for monitoring exercise intensity are heart rate and rating of perceived exertion. Both can be self-monitored, and each has its advantages.
Exercise Heart Rate
Your exercise heart rate is the number of times your heart beats per minute during exercise. Because physical activity increases the demand for oxygen in the working muscles, your respiratory and heart rates both increase to meet oxygen demands. Over time, exercise that causes an increase in heart rate will have the effect of improving the efficiency of the heart and lungs to provide oxygen, and the efficiency of the muscle cells to use it. Exercise heart rate is a quantitative measurement and when calculated using traditional methods, takes a one-size-fits-all approach to assigning recommended ranges. While heart rate can be an effective tool for monitoring cardiovascular exercise intensity, it is less useful for activities like resistance training.
Rating of Perceived Exertion
Rating of perceived exertion, or RPE, is a qualitative system in which you evaluate your exercise intensity based on how you feel, or your perception of difficulty. According to the American College of Sports Medicine, or ACSM, "the RPE scale measures feelings of effort, strain, discomfort, and/or fatigue experienced during both aerobic and resistance training." Rating of perceived exertion is an easier way to assess intensity than heart rate because it does not require a timer or heart rate monitor. RPE is relative to individual perceptions of difficulty and individual physiological makeup. Its drawback lies in being subject to variance in individual tolerance for discomfort, but the more it is used, the more useful it becomes for giving a comparative perception of difficulty.
Training Heart Rate Range
Your training heart rate range is the performance zone within which you will realize physical adaptations, or a training effect. For most people, the ACSM recommends a range of 60 to 80 percent of your maximal heart rate. To determine maximal heart rate, subtract your age from 220, then multiply that number by .60 and again by .80 to find your target heart rate range. Many types of cardiovascular equipment have built-in heart rate monitors. However, in his book "Heart Rate Training," distance-running coach Roy Benson says individualization based on your current fitness level, general ability and goals is important. There are an increasing number of "smart" heart rate monitors that allow you to program personal data to customize a heart rate-based workout.
RPE Scales
According to the University of Wisconsin-Waterloo, the rating of perceived exertion scale was developed by Gunnar Borg to provide a way of estimating exertion for various people and tasks. Borg's original scale used a ranking from 6 to 20, which was later modified to the CR10 scale, with a zero-to-10 ranking. The scales' values range from "no exertion at all" to "maximal exertion," with gradients of light, moderate and heavy between. To achieve a training effect during general fitness activities, your exertion should range from about 5 to 8, or "strong" to "very strong" on the CR10 scale.
References
- American College of Sports Medicine: ACSM Current Comment: Perceived Exertion
- Human Kinetics: Individualization Guarantees Results From Any Exercise Program
- Mayo Clinic: Heart Rate: What's Normal?
- American College of Sports Medicine: Selecting and Effectively Using Heart Rate Monitors
- University of Wisconsin-Waterloo: RPE Scales
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