Friday, July 25, 2008

Are You Still Using Heart Rate?

Are you still using heart rate as an indicator of exercise intensity? Shame on you. Most trainers, at one time or another, have used (or still use) heart rate to measure the individual's response to the intensity of an exercise. Ask yourself, have their been times when your client has been walking on a treadmill and you noticed an elevated heart rate reading--even though they were only walking on a 2.5 speed? Did you wonder what the deal was? Let's guess...you decreased the speed of the treadmill so that their heart rate would decrease?

Now they are walking at a snail's pace.

After a few minutes their heart rate is returned to a "normal safe zone" and you feel that you are acting as a "responsible trainer". Truth is, you are wasting your clients' and your time. You are creating ZERO training effect based on an invalid reliant.

Here's why: Sedentary individuals typically do not engage in regular physical activity and therefore view ANY activity as a mountainous task. That's not uncommon as mental barriers play a role in being inactive--especially in a gym-setting. The act of moving a limb for a sedentary person can be a daunting task--especially on treadmill or bicycle. The contraction of skeletal muscle during movement causes a "pressor response" which is governed by the autonomic nervous system. It causes an increase in heart rate with a corresponding reduction in stroke volume.

According to Cedric Benson of the American Council on Exercise (ACE), "...even though heart rates are increased during resistance training, the oxygen uptake is not increased to the same degree as it is during aerobic conditioning. This factor minimizes the metabolic overload to the muscles and, therefore, limits the aerobic training benefit that can occur as the result of resistance training. The pressor response helps to explain, from a physiological standpoint, why the heart rate is disproportionately elevated, relative to oxygen uptake, during resistance training."

I have found in my experience that the "talk test" and the RPE scale are the most effective (for the trainer) when gauging a client's response to a given exercise stimuli. Heart rate monitors are effective for people who participate in aerobic-style exercise (marathon, cycling) that have experience with deciphering their body's response.

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