Alfreda Smith asked:
People have been telling me that when you excercise too fast that all you are doing is burning muscle and not fat. I do step aerobics at a fast pace three times a week. If you work over your maximum heart rate do you burn muscle? And how do you know your heart rate with those 6 and 10 second counts aerobics instructors usually do?
Larry DeLuca, EdM, CSCS
Lots of questions...
The key factor in determining whether or not you lose primarily body fat or primarily muscle is the amount of deficit (the difference between the calories you take in and the calories you expend). Keeping your deficit to around 250-1000 Calories per day will result in a weight loss of about 1/2 to 2 lbs. per week, primarily from fat. Larger deficits will result in a shift toward losing more muscle.
The intensity should range from .50 to .85.
If your instructor counts for 6 seconds, divide the numbers by 10 to get your training range for a 6-second count. If your instructor counts for 10 seconds, divide the heart rate numbers by 6. For example, if you are training at a heart rate of 150 BPM, a 6-second count would be 15 beats, whereas a 10-second count would be 25 beats.