Unless you are medically trained, you will most likely find it hard to tell what is going on inside your body and even harder to ascertain if your heart is functioning just right. For starters, you could take your own pulse, and learn what your heart rate might be saying about your health.
Calculating your resting heart rate
To get you started, here’s how you measure your heart rate:
1. Place your index and 3rd fingers on your neck to the side of your windpipe. Alternatively, place 2 fingers between the bone and tendon over your radial artery – which is located on the thumb side of your wrist.
2. When you feel your pulse, count the number of beats in 15 seconds. Multiply this number by 4 to calculate the number of beats in a minute.
To avoid miscalculating your heart rate, you are advised not to measure your heart rate within 1 – 2 hours after exercise or a stressful event. Your heart can stay elevated after strenuous activities. You will also want to wait at least an hour after consuming caffeine, which can cause palpitations and make your heart rate rise.
What is a normal heart rate?
When we talk about your heart rate, we are actually referring to your resting heart rate. Medically defined as the ‘lowest amount of blood you need when you are not exercising’, your resting heart rate is the rate at which your heart is pumping the minimum amount of blood you require to go about your day-to-day activities.
The normal resting heart rate for adults, including older-aged adults and everyone above 10 years old, is between 60 – 100 beats per minute (bpm). It is natural for heart rates to get progressively slower through childhood towards adolescence. To break it down further, these are normal ranges for resting heart rates according to age:
Newborns below 1 month: 70 – 190 bpm
Between 1 – 11 months: 80 – 169 bpm
Age 1 – 2: 80 – 130 bpm
Age 3 – 4: 80 – 120 bpm
Age 5 – 6: 75 – 115 bpm
Age 7 – 9 years: 70 – 110 bpm
Age 10 – 18: 60 – 90 bpm
Age 18 and above: 55 – 80 bpm
For well-trained athletes, their heart rate can average 40 – 60 bpm.
Many factors influence resting heart rate. Genes play a role. Ageing tends to speed it up while regular exercise tends to slow it down. Stress, medication, and medical conditions also influence the heart rate.
The normal heart rate undergoes healthy variation in response to changes in body conditions, including exercise, body temperature, body position (eg. standing up too quickly), and emotions such as anxiety and arousal.
If your resting heart rate does not fall in the normal range as listed above, does it always point to a bigger medical condition?
When your heart rate is irregular
Medically coined as arrhythmia, this is when your heart rhythm is abnormal. It does not necessarily mean your heart is beating too fast or too slow, it just means your heart is out of its normal rhythm.
The heart normally beats in regular, synchronised time with an internal ‘electrical circuit’ controlling the rhythm. Abnormalities in this circuit can cause fast, slow or irregular heart rhythms.
Arrhythmias can be an emergency or completely harmless. In fact, you could experience irregular heartbeat even if your heart is healthy. It could happen because you have:
- Heart disease
- Imbalance of electrolytes (such as sodium or potassium) in your blood
- Changes in your heart muscle or structure of your heart
- Injury from a heart attack
- Healing process after heart surgery
When your heart beats too fast
Doctors call it tachycardia when your heart beats very fast for a reason other than exercise, high fever or stress. For most people, the heart still works normally to pump blood through the body.
During an episode of tachycardia, the heart beats at least 100 beats a minute and may reach 300 beats a minute. These episodes may start and end quickly, and you may not even notice any symptoms at all. The condition only becomes a problem when it happens often, lasts too long, or causes symptoms such as a pounding pulse, dizziness, shortness of breath, fainting spells, chest pain or tightness.
If you notice your resting heart rate increasing, it is a sign worth watching. A fast resting heart rate can indicate the start and progression of heart disease.
When your heart beats too slow
On the other hand, when your resting heart beats very slowly, doctors call this bradycardia. For most people, a heart rate of 60 – 100 bpm while at rest is normal. If your heart beats less than 60 times a minute, it is slower than normal.
For some people, a slow heart rate does not cause any problems. It can be a sign of being very fit. In other people, bradycardia is a sign of a problem with the heart where the heart may not be pumping enough blood to meet the body’s needs. Some symptoms include dizziness, fainting spells, shortness of breath or increasing difficulty in exercising, tiredness, chest pain or a pounding in your chest.
Bradycardia can be caused by changes in the heart as a result of ageing, heart diseases (eg. coronary artery disease, heart attack), low thyroid levels or the consumption of medication for treating heart problems or high blood pressures.
Crossing into the danger zone?
Now we know too fast or too slow a heart rate may or may not indicate underlying problems. How then should you determine when your heart rate is entering a dangerous zone?
Depending on your age, the human heart can normally beat up to 220 times per minute, and that maximum can only be attained by a young child. If you want to determine your maximum heart rate, subtract your age from 220. You’d notice that your maximum heart rate declines with age.
It is hard to ascertain when your heart rate is crossing into the danger zone but if you notice anything unusual about your heart activity or if you develop symptoms described above, consult your doctor early for a check-up or go for a heart screening.
Article reviewed by Dr Leslie Tay, cardiologist at Mount Elizabeth Hospital
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