High heart rate, super intensity and excessive duration of exercise can cause the body to seek protein -- in addition to other fuel sources such as glucose, fat and oxygen -- to produce energy. High heart rates, estimated at between 85 and 100 percent of maximal heart rate -- or MHR -- burns protein. Protein comes from the muscles; however, you will still be burning more fat than at lower heart rates because of the extra effort.
Define the Purpose of Your Exercise
If you want to lose a lot of weight as fast as possible, a combination of low and high heart rates will meet your goals more quickly. The higher heart rates may cause you to burn more glucose, but the intensity will burn more calories, and in the final analysis, weight loss is a matter of decreased calorie intake and increased calorie expenditure. If you want to lean out but retain or gain muscle mass, you will be better off performing cardio at the fat-burning zones, estimated to be between 70 and 80 percent of MHR.
Calculating Heart Rate
Calculating heart rate, whether you take your pulse or use the meter provided on most cardiovascular equipment, is still just an estimate. Individual heart-rate monitors are more accurate, but these are based on a person's MHR, which is also an estimate.
MHR is estimated at 220 minus your age. The Mayo Clinic states that some people may vary from this average by as much as 15 to 20 beats per minute.
Beta blockers, antiarrhythmic medications, some calcium blockers and digoxin can lower your MHR, and your target heart rate -- or THR. The most accurate measurements can be obtained with a personal heart-rate monitor under the guidance of an exercise physiologist or licensed personal trainer.
Starting Out
If you're just starting out on an exercise program, stay in the lower limits of your target heart rate, between 60 and 75 percent. Slowly build up your aerobic capacity over weeks and months of regular aerobic exercise. The "talk test" is a generally accepted test of when you are pushing too hard. If you cannot sing the refrain "Old McDonald had a farm, ee, ei, ee, ei, oh," then you need to turn it down a notch.
Finessing Fat Burning
As your conditioning improves, you can begin to experiment with interval training. With this system, you will spend several minutes in your THR, "sprint" into your upper limits for a shorter period of time, and then ease back to your THR. In this manner, you won't be cannibalizing muscle, but you will be burning lots of fat calories, and your total calories will be much higher than if you stayed within your THR the entire time.
Finish off a workout at the upper ranges of your THR with a protein drink or shake for recovery fuel that doesn't come from your muscles.
Member Comments