The use of heart rate monitors is now common practice among many runners – but how much do we really know about resting heart rate? An indicator of aerobic fitness, a lower resting heart rate generally implies more efficient heart function. But are there exceptions and what warning signs should runners be looking out for? RW sat down with leading sports cardiologist Dr Dan Augustine to find out more.
What is a normal resting heart rate?
‘The average resting heart rate in the general population will vary between 60-100 beats per minute (bpm). I think it’s fair to say that the lower that is, generally the fitter you are. In those that exercise, I’d expect heart rates to be much closer to 60bpm, and it’s not uncommon for recreational runners to have heart rates in the 40s.’
Is a high or low heart rate cause for concern?
‘It’s about how you feel with that heart rate. So, if you have a resting heart rate of 90, but you feel fine going about your daily business, I don’t worry.
‘But if you’re having abnormal symptoms at rest, such as disproportional breathlessness, you need to get it checked out. Another concern would be people with heart rhythm disturbances who get disproportionately high heart rates for the level of exertion they’re putting in. For example, where you’d expect their heart rate to be about 140, it’s at 180, and stays high for a while after stopping exercise or reducing exercise intensity. We also shouldn’t feel dizzy or faint as we are exercising, particularly as we increase the intensity of exertion. So if this is happening, it’s something to get checked out.
‘For people with a low heart rate, a symptom to look out for would be if you start to feel dizzy or faint. That’s unusual and you should seek advice. So I worry more about symptoms accompanying heart rate rather than just the number itself.’
What effect gender have on resting heart rate?
‘The average female resting heart rate is slightly higher than the average male resting heart rate. The average male is around 70ish beats per minute; the average female is a couple of beats per minute higher. That’s largely driven by the difference in size between men and women: female hearts are slightly smaller so they beat a bit quicker to get to the required cardiac output.’
What effect does age have on resting heart rate?
‘When you’re an adult, the resting rate doesn’t vary much with age. What varies is your peak heart rate. There are few ways to try to calculate your peak heart rate, some more accurate than others. The equation ‘220 minus your age’ was first written about in the 1970s and not intended to be applied strictly as it has faults. In younger people, it probably overestimates what your peak heart rate should be. In older people, it probably underestimates what your peak heart rate should be.’
Why is it important for your heart rate not to be too high?
‘What you have to be mindful of is what’s causing it to be high. If there’s a medical condition causing it to be high, such as anaemia or an over-active thyroid, that will cause a faster heart rate. Sometimes, a faster heart rate can be a sign that something else is going on. Then it comes down to your efficiency. At rest, your heart’s not meant to be having a cardiac output of 8 litres [the average is 3-4 litres per minute], but if you have a really high heart rate, it will cause a high cardiac output. So you have to work out why that is.’
How can you go about lowering your resting heart rate?
‘There’s not one thing on its own, but exercise will certainly help. Generally getting fitter with aerobic exercise will lower the resting heart rate in most, depending on how much you are doing. We know that if you undertake regular aerobic exercise, probably more than three hours a week, then the heart will start to adapt and undergo physiological changes. One of these will usually be a reduction in the resting heart rate. There are a few reasons why heart rate lowers the more aerobic exercise you undertake. These include the heart size itself becoming bigger so the heart doesn’t have to beat so fast to increase the cardiac output. Also, we all have a pacemaker in our heart – called the sinus node – and through regular exercise it’s believed that sinus node down-regulates slightly and lowers the heart rate. In addition, exercise can enhance part of the nervous system, something called the parasympathetic or vagal tone, which can lower resting heart rate.’
The effect does nutrition, sleep and stress have on the resting heart rate?
‘Anything that upsets are physiology – whether that’s poor nutrition, lack of sleep or physical and emotional stress – can impact on the resting heart rate and cause it to be higher. Our ‘rest’ time where we are not exercising can often be neglected but it’s really important to get the balance right from a physical and psychological perspective. That includes getting enough sleep, identifying stressors in our lives and modifying those as much as possible. It’s important from a general health perspective to also have a healthy diet. Factors such as eating fruit, vegetables, whole grains and controlling alcohol consumption will all contribute to a healthy physiology and a lower heart rate in the longer term.’
Dr Dan Augustine is a sports cardiologist: screenmyheart.co.uk
