RPE may be better measure than heart rate for workouts

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By Kent Pegg

One of the more difficult decisions to make when exercising is how hard to exercise to get the most out of your workout. Should you exercise at low intensity or high intensity? And what, exactly, does low intensity and high intensity feel like?Fortunately, there are ways to determine just how hard you’re working and what the intensity should be.While exercise intensity can be determined through monitoring your heart rate, that’s not always the easiest or most cost-effective method. Heart rate monitoring can be difficult to master and difficult to assess during intense exercise. Also, when determining exercise intensity through heart rate monitoring, it may be necessary to periodically revise your target heart rate as your level of conditioning changes. Also, to determine a good target heart rate you need to take into account your resting heart rate. For instance, a chart will show the same target heart rate for two people the same age even if one has a resting heart rate of 55 and the other 95.Another method for assessing the level of your exercise session is to use a rating of perceived exertion (RPE). A rating of perceived exertion allows a person to assess how hard they are working depending solely on how they feel.Incorporated into this assessment should be all the sensations and feelings your body is providing during your exercise session. These should include your effort, muscle fatigue, endurance depletion and physical stress.Many different scales exist for monitoring your RPE. Gunnar Borg developed the Borg scale in 1982. It uses a scale that measures intensity from a level of 6 to a level of 20 with the following intensity equivalents:

•  6 – no exertion at all• 7-8 – extremely light exertion•  9-10 – very light exertion•  11-12 – light exertion•  13-14 – somewhat hard exertion•  15-16 – hard exertion•  17-18 – very hard exertion•  19 – extremely hard exertion•  20 – maximum exertion On the Borg scale, most aerobic or cardiovascular exercise is performed at a level of 12 or 13.The Borg scale can also be used to provide an estimate of your heart rate. For many, multiplying the Borg scale number by 10 will give you your approximate heart rate. This will be just an estimate and, as with any RPE scale, you should check your numbers against your measured heart rate periodically.While the Borg scale is an effective measure of exercise intensity, it can be difficult to estimate your level of exertion on a scale of 6 to 20. An easier method was developed in 1986 when the American College of Sports Medicine revised the scale to a 0 to 10 system, with zero being the lowest level of effort, ten the highest, and the following additional breakdowns:

•  0 – nothing at all•  1 – very weak•  2 –weak•  3 – moderate•  4 – somewhat strong•  5-6 – strong•  7-9 – very strong•  10 – very, very strong

With the modified 0 to 10 scale, aerobic exercise is best performed while working between levels 4 and 6 on the scale.Still other rating scales exist. The Reebok University’s Effort Scale measures training effort on a scale of 1 to 4.

•  Level 1 – light to moderate•  Level 2 – moderate•  Level 3 – moderate to hard• Level 4 – hard to extremely hard

No matter what scale is used the main principle of an RPE scale remains the same – it is an easy and efficient way to monitor your exercise intensity during any exercise or activity, whether you’re doing a weight lifting or cardio workout at the gym or shoveling snow or skiing this winter.Another great thing about an RPE is that it will continue to work for you over time when a target heart rate might let you down. For instance, your target heart rate can change depending on your level of conditioning but an RPE of 7 will always be an RPE of 7. You just might have to work a little harder to feel that level 7 as you become fitter.The RPE scales provide a double-check on your heart rate, are easily performed without interrupting your exercise, and require no additional equipment. Plus, the more you use an RPE scale, the better you get at truly assessing your level of exercise intensity.So consider using a rating of perceived exertion scale to monitor your exercise intensity and begin getting the most out of your exercise sessions.

NOTE: As part of the LAFC Monthly Health Series, Los Alamos Fitness Center is offering a special class on Cold Weather Exercise and Winter Sports. Classes will be held Mondays at 1 p.m. These classes are free to the public and everyone is welcome to attend. For more information call 662-5232.

Kent Pegg is a certified personal trainer and the owner of the Los Alamos Fitness Center. If you have any questions about the information or exercises in this story you can call him at 662-5232.