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Exercise Column

Heart rate is used to indicate aerobic intensity levels

In many exercise programs different heart rate (HR) levels to work out at are given on different days. Those HR levels represent different intensity levels. By measuring your HR while you workout you get an indication of the amount of stress you are applying to your body.

Workout lightly, with little rise in your HR and you might be doing a recovery workout - stimulating your body to enhance repair by increasing the delivery of nutrients to your muscles and organs and enhancing the removal of waste products. Working out harder, with a greater rise in your HR may stimulate improvements in conditioning.

When exercise is aerobic, heart rate can be used as an indicator or how hard you are working out - or exercise intensity. That is not the case with anaerobic exercise like weight lifting or sprinting.

With aerobic types of exercise like walking, jogging, and spinning the increase in your HR represents an increased oxygen delivery to the cells of your body and an increase metabolism.

With anaerobic forms of exercise, part of the increase in your HR is due to the metabolic demand but part is due to other factors including: movement, build-up of metabolic waste products (including lactic acid), increased body temperature, increased levels of stress hormones, etc.

So , no, it is not true that by working out with weights in a circuit fashion trains your muscles along with your heart and in doing so improves both your appearance and your cardiovascular fitness. Actually while it might impact both systems neither is actually stressed optimally or improves as much as when both types of conditioning are performed separately.

The gyms and fitness programs that market those types of programs want you to believe that. But basically it is a marketing technique to get people in and out of their facility quickly and have them believing they are getting more "bang for their buck."

Written by Dr. Sternlicht for on 1.28.06