The importance of a healthy heart rate

“We don’t want people to over-exercise, and the other extreme is not getting enough exercise,” says Gerald Fletcher, M.D., a cardiologist and professor in the Mayo Clinic College of Medicine in Jacksonville, USA.

Many of us have gadgets that measure our heart rate (HR) but do you know how to monitor your HR so you can improve your fitness, maintain a healthy heart and burn fat?

Your HR is the number of times your heart beats per minute (bpm).   It varies throughout the day depending on what you are doing, how stressed you are, etc. It is an important way to monitor your fitness, especially the fitness of your heart. As you age, the rate and regularity of your pulse can change and may signify a heart condition or other problem that needs to be addressed.

The resting HR varies between different people but should be between 60 -100 bpm. It is best to measure your HR first thing in the morning. You can measure your HR easily if you have a HR exercise monitor such as a Fitbit, Apple Watch or a chest strap heart rate monitor. They do give variable results, with the chest strap being the most accurate, but they can be useful.  You can take your pulse yourself using your wrist or your neck. To check your pulse at your wrist, place two fingers between the bone and the tendon over your radial artery, which is located on the thumb side of your wrist and for your neck, place your index and third fingers on your neck to the side of your windpipe.  Measure your pulse for 15 seconds and multiply this by 4 to get your bpm.

Generally a lower HR means that you are fitter with a more efficient heart as less effort is needed to pump blood around the body. A fit person will normally have a resting HR of 50-60 bpm and a really fit athlete may have a resting heart rate as low as 40 bpm.

If your heart rate is too low or too high, this can cause problems. A resting HR over 100 bmp results in tachycardia where the heart is pumping too fast and it may not be efficient at getting oxygen to the organs and you may feel light headed, have shortness of breath, a rapid pulse, heart palpitations or chest pain.   If your heart rate is too low you may have bradycardia where your brain and other organs are not getting enough oxygen and you may experience feinting, dizziness, shortness of breath, chest pains and be easily tired.

The heart is a muscle and as with other muscles, it needs physical activity to keep it in good condition. Inactivity is one of the major risk factors of heart disease. People who exercise reduce their risk of cardiovascular disease by 45% compared to those who do not exercise. If it is performing well, the heart can pump blood around the body, including the brain, efficiently and with less strain. Even a small amount of exercise is beneficial but those who exercise often and vigorously have the lowest risk of heart disease. Exercise works by keeping the blood vessels open, reducing inflammation of the arteries, reducing the levels of bad cholesterol (LDL), increasing the levels of good cholesterol (HDL) in your blood and helping to keep a healthy weight.

When we exercise our HR and breathing increases as the heart needs to pump more blood around the body so that the muscles can get more oxygen and glucose and the blood can get rid of carbon dioxide.

To feel the benefits of exercise we need to increase our HR. If your HR is not increasing enough, you may need to pick up the pace and vice versa. With my Apple watch I have realised that sometimes it measures a walk as exercise and sometimes it does not. I have assumed that this is because sometimes my HR is not increasing enough to register it as exercise.

Exercising at different intensities brings different rewards. At lower intensities, you burn fat and at higher intensities you burn glycogen. Apparently the best HR to burn fat is 65% of your maximum HR. Your maximum HR is the upper limit of what your cardiovascular system can handle during physical activity.

100% maximum HR is calculated as 220 minus our age, so for a woman of 50, this would be 170bmp. But this is only a rough guide and depends on other factors so it could be 15-20 bpm out. If you want a more exact maximum HR, you should discuss this with your personal trainer but usually only elite athletes are concerned about being so accurate.

Image credit – https://www.2ndwindexercise.com/blog/the-cardio-zone/

To work out what your HR should be when you exercise at certain intensities, we calculate the HR zone (see the above graph). This can be calculated in two ways: as a percentage of your maximum HR or it can take into account your fitness levels – unfortunately the two methods do not give the same number so this is a bit confusing. Either way, when exercising, you should aim to work at an intensity that is right for you but roughly between 55-85% of your HR zone for at least 20-30 minutes. Working at 60-70% of your HR zone will burn fat and build endurance, working at 70-80% will improve weight management and cardiovascular fitness and working at 85-100% will improve athletic performance but will not burn body fat as the body will get energy from burning carbohydrate from glycogen stored in the muscles.

To calculate your HR zone as a percentage of your maximum HR, you simply work out what intensity you want to work out at and take this as a percentage of your maximum HR. So if you are a 50 year old woman who wants to work at 70% of her HR zone, her maximum HR will be 220-50=170 and 70% of this is 170=0.7 = 119bpm.  If you visit this web site – it will calculate this for you.  https://www.active.com/fitness/calculators/heartrate

To work out your HR zone taking into account your fitness is called The Karvonen Formula. You can go to this web site that will work out your HR taking into account your resting HR – https://www.fitwatch.com/calculator/target-heart-rate.   You will need to know your resting HR. So in our example, our 50 year old woman has a maximum HR of 170bpm. Then we calculate her heart rate reserve (HRR) by subtracting her resting HR from her maximum HR. So for example, her resting HR is 70bpm, so her HRR will be 170-70=100bpm.   If she is aiming at working at 70% of her maximum HR, we multiply her HRR (100) by 0.7 to get 70 and finally, add her resting HR, so in our example this would be 70+70=140bpm. So this person needs to increase her HR to 140bpm to be exercising at 70%.  You can see this comes out with a slightly different number than the first method – which is a bit confusing.

You will have seen adverts talking about using walking for weight loss. Walking is an excellent exercise for fat burning, as long as you increase your HR enough. While any exercise can burn calories, brisk walking for 45 minutes mobilizes the body to dip into fat reserves and burn stored fat. Walkers can achieve the exercise intensity that uses more fat as fuel.

No matter what exercise we do, what is also important is the recovery time which is the time it takes for your HR and breathing to return to normal after exercising – called the heart recovery rate. The fitter you are, the shorter this is.  Breathing deeply helps to lower your heart rate but it is also important to breathe properly when you exercise.  When you stop exercising, your HR should fall by 20 bpm per minute.  People who have a reduction of 12 or less during that first minute are at a higher risk of suffering a heart attack later in life. Obviously this is affected by how long you have been working out and to what intensity. The important thing is that it should return to normal quite quickly.

If you have not exercised for a while, it is always advisable to start slowly but this is especially true if you have heart disease, diabetes, are over 45 years or are on any serious medication. Please talk to your doctor before starting an exercise programme.

Have you never measured your HR? Do you measure your HR regularly?  Do you try to ensure you work out at the right intensity?  Which method do you use to work out your HR zone?

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