The Borg CR10 scale is a subjective measurement tool designed to quantify how hard a person feels they are working during physical activity. Developed by Swedish researcher Gunnar Borg, this scale is known as the Category-Ratio 10 scale because it combines verbal descriptions with numerical ratings. It serves as a precise method for assessing the intensity of effort, or perceived exertion, across various settings. This instrument is used extensively in clinical research and fitness environments to monitor and prescribe exercise intensity.
Measuring How Hard You Feel
The concept of Perceived Exertion (RPE) captures the subjective intensity of effort experienced during physical activity, integrating all the signals the body sends. These internal sensations include the strain in the working muscles, the increased rate of breathing, and the feeling of a faster heartbeat. By translating these complex physical feelings into a single number, RPE provides a comprehensive measure of total physiological stress.
Objective measures, such as heart rate or oxygen consumption, are valuable, but they do not always reflect a person’s complete experience. Experience can be influenced by factors like fatigue, illness, or medication. Using a subjective scale allows individuals to tune into their body’s unique response to exercise, offering a personalized view of intensity and effort that complements machine-based data.
Decoding the CR10 Categories
The Borg CR10 scale uses a numerical range from 0 to 10, where each number is anchored by a verbal description to ensure consistency in interpretation. A score of 0 represents “Nothing at all,” reflecting complete rest. Moving up the scale, a rating of 1 is anchored to “Very light” effort, while a 3 is typically described as “Moderate” exertion.
The scale is designed so the numbers represent a ratio of effort; for example, a score of 6 should feel like twice the effort of a score of 3. The higher end progresses from a 5, which is “Severe” or “Heavy,” to a 7, which is “Very severe” effort. The maximum point, 10, is reserved for the “Maximal” or “Highest possible” effort an individual has ever experienced. This category-ratio structure allows users to rate effort levels that fall between the main verbal anchors using half-points, such as 4.5.
Using the Scale to Manage Workouts
Personal trainers and athletes use the CR10 scale to precisely set and monitor training intensity, ensuring workouts are effective. Before starting, individuals undergo an “anchoring procedure,” where they perform a maximal effort to establish what a score of 10 truly feels like for them. This calibration ensures future ratings are accurate and consistent with their own physical limits.
For a moderate-intensity aerobic session, a coach might prescribe a target range of 3 to 4 (“Moderate” to “Somewhat severe”) to maintain a steady pace. High-intensity interval training (HIIT) requires alternating between a score of 7 (“Very severe”) during work periods, and a score of 1 or 2 during recovery. By focusing on the prescribed number, exercisers can adjust speed, resistance, or weight in real time to match the desired internal feeling of effort. This method is useful in resistance training, where the sensation of muscle fatigue is often more descriptive of effort than heart rate alone.
Why the CR10 Scale Was Created
The Borg CR10 scale was created as a modification and simplification of the original Borg RPE 6-20 scale. The older 6-20 scale was developed so its numbers would roughly correlate with a person’s heart rate when multiplied by 10. However, this correlation became unreliable in various populations, such as those taking certain medications or individuals with different fitness levels.
The CR10 scale was designed to be more intuitive and user-friendly, resembling a familiar 10-point rating system. It was established as a true category-ratio scale to better reflect the psychophysical relationship between the perceived intensity and the actual physical stimulus. This design makes the scale highly effective for rating specific sensations, such as muscle pain or breathlessness, in addition to overall exertion, expanding its utility across medical and rehabilitative settings.