Is It True That One Starts To Burn Muscle Above 142 Heart Rate?

Question

When doing cardio exercise.

Answer 1

Hey there
It depends on your age, but look at it like this, to lose weight & burn fat, you need to work at a 65-70% target heart rate, if you go above this target heart rate and work safely you have to be very fit, but for a normal person working between 70-80% target heart rate the the body starts to access stored sugars (glycogen) from your muscles to fuel itself, so yes, you burn lean muscle instead of fat. The theory is that you can maintain intensity at 65% THR, thereby accessng slow burn (fat) fuel.

Answer 2

you're going up into the heart palipatations levels now.

that's definately a burn...

you'll burn much actually along with brain cells.

Answer 3

Probably the most important thing to note is that no one can give you a number for when you are going to burn muscle. This is not at a certain number and heart rates vary GREATLY from person to person and different ages. The short answer to your question is "no", it is not true. I am providing you with some links to study to see if you can find out some more information about heart rate. To build muscle and burn fact and get the most of your cardiovascular exercises, you should certainly measure your heart rate and see what is ideal for you.

I suggest you begin with the following reading from the American Heart Association. They have a great website: www.americanheart.org and some specific pages are listed for you in the sources section.
Question

What is a safe heart rate when I am exercising?

Answer

To calculate your target training heart rate, you need to know your resting heart rate. Resting heart rate is the number of times your heart beats per minute when it's at rest. The best time to find your resting heart rate is in the morning after a good night’s sleep and before you get out of bed. The average resting heart rate is 60–80 beats per minute. However, for people who are physically fit, it’s generally lower. Also, resting heart rate usually rises with age.

Once you know your resting heart rate, you can then determine your target training heart rate. Target heart rates let you measure your initial fitness level and monitor your progress in a fitness program. You do this by measuring your pulse periodically as you exercise and staying within 50 to 75 percent of your maximum heart rate. This range is called your target heart rate.

The table below shows estimated target heart rates for different ages. Look for the age category closest to yours, then read across to find your target heart rate. Your maximum heart rate is about 220 minus your age. The figures below are averages, so use them as general guidelines.


Age
Target HR Zone
50-75 %
Average Maximum
Heart Rate
100 %

20 years
100–150 beats per minute
200 beats per minute

25 years
98–146 beats per minute
195 beats per minute

30 years
95–142 beats per minute
190 beats per minute

35 years
93–138 beats per minute
185 beats per minute

40 years
90–135 beats per minute
180 beats per minute

45 years
88–131 beats per minute
175 beats per minute

50 years
85–127 beats per minute
170 beats per minute

55 years
83–123 beats per minute
165 beats per minute

60 years
80–120 beats per minute
160 beats per minute

65 years
78–116 beats per minute
155 beats per minute

70 years
75–113 beats per minute
150 beats per minute


Important Note: A few high blood pressure medications lower the maximum heart rate and thus the target zone rate. If you're taking such medicine, call your physician to find out if you need to use a lower target heart rate.

After the links from the AHA, I have a few more. The fourth link provided is to a heart rate calculator from Yahoo! Health. This should be helpful for you and give you more specific numerical values for yourself. The last is a Wikipedia article. An important part of that is as follows:
Heart rate is a term used to describe the frequency of the cardiac cycle. It is considered one of the four vital signs. Usually it is calculated as the number of contractions (heart beats) of the heart in one minute and expressed as "beats per minute" (bpm). See "Heart" for information on embryofetal heart rates.

When resting, the adult human heart beats at about 70 bpm (males) and 75 bpm (females), but this rate varies between people. However, the reference range is nominally between 60 bpm (if less termed bradycardia) and 100 bpm (if greater, termed tachycardia). Resting heart rates can be significantly lower in athletes. The infant/neonatal rate of heartbeat is around 130-150 bpm, the toddler's about 100-130 bpm, the older child's about 90-110 bpm, and the adolescent's about 80-100bpm.

Good luck! I hope this helps answer your question.