Despite how fundamental they are to our existence, most of us rarely think about our heartbeats until, say, a surge of adrenaline causes us to become conscious of the fluttering in our chests. Beats are also noticeably faster in moments of stress or excitement, after we\u2019ve consumed caffeine and when we exercise. This has led some to speculate that overdoing it at the gym or performing other intense physical activities effectively burns through a heartbeat reservoir, shortening our lifespan. <\/p>\n
\u201cIt is likely that this notion that we are born with a fixed number of heartbeats comes from early physiological observations across mammalian species where scientists noticed that smaller animals with faster heart rates tended to have shorter lifespans,\u201d says Tim van Puyvelde, a cardiologist at the KU Leuven research university in Belgium. <\/p>\n
This \u201cfinite heartbeat theory\u201d has been perpetuated by, among others, the US president Donald Trump. In their 2016 book Trump Revealed, the Washington Post journalists Michael Kranish and Marc Fisher noted: \u201cTrump believed the human body was like a battery, with a finite amount of energy, which exercise only depleted.\u201d Golf, apparently, is an exception, being a sedate enough sport to do no harm.<\/p>\n
It is true that overexertion during extreme endurance training and athletic events can put midlifers at a slightly greater risk of developing issues such as an irregular heartbeat, aka atrial fibrillation, as was outlined in the British Journal of Cardiology this year. Yet endurance runners don\u2019t die younger than everyone else \u2014 indeed, the opposite may be true: a 2023 study of 4,500 people by a team at Brigham Young University in the US found that those who ran for at least 75 minutes a week had a biological age about 12 years younger than those who ran for less than 10 minutes a week or not at all. <\/p>\n
For most people, exercise lowers the chance of developing cardiac issues. And comparing the human heart to a Duracell battery overlooks the fact it is a muscle that can be strengthened through aerobic activity, the consequence of which is that the heart is likely to become more efficient and pump more blood per beat, leading to a lower resting heart rate.<\/p>\n
Van Puyvelde was interested in how the number of heartbeats expended during exercise and the number subsequently saved by the heart\u2019s resultant increased efficiency could be used as a metric to calculate \u201ca heartbeat budget\u201d \u2014 a measure of how wisely we are \u201cspending\u201d or \u201csaving\u201d our body\u2019s most valuable commodity.<\/p>\n
\u2022 Does it matter if my resting heart rate is high?<\/a><\/p>\n With colleagues at the St Vincent\u2019s Institute of Medical Research in Melbourne, he investigated the potential health implications of intense exercise training by analysing heart rate data from fitness monitors used by 109 endurance athletes and 38 healthy nonathletes in a controlled study. Predictably super-fit individuals were found to have a significantly lower resting heart rate, resulting in fewer total daily heartbeats compared with the healthy controls. Results showed that the average heart rate was 68 beats per minute for athletes and 76 beats per minute for the more sedentary group. <\/p>\n Over a 24-hour period this worked out at about 109,440 heartbeats in the nonathletic group compared with 97,920 heartbeats in the endurance-trained participants, representing a heartbeat \u201csaving\u201d of about 11,500 beats a day. \u201cThat 10 per cent difference adds up over time,\u201d Van Puyvelde says. \u201cIt shows the fitter you are, the more metabolically efficient your body becomes.\u201d The results, published in the Journal of the American College of Cardiology Advances, roundly dispel the myth that endurance exercise uses up your heartbeats to ill effect. <\/p>\n \u201cOverusing your heart isn\u2019t the problem; it\u2019s not using it enough that might be an issue in the long term,\u201d explains Tom Brownlee, an assistant professor in applied sport sciences at the University of Birmingham. Even if you\u2019re working out intensely for an hour or two a day, the reality is that your heart beats more slowly and efficiently for the other 22 or 23 hours. \u201cThe net result is that your heart tends to beat less frequently overall in the course of your lifetime.\u201d<\/p>\n Echoing Brigham Young University\u2019s findings, recent epidemiological studies have shown that even elite endurance athletes, who were once thought to die earlier than the general population, have increased lifespans compared with the rest of us. A 2023 report by the International Longevity Centre at City University of London looked in detail at the lifespan of Commonwealth Games competitors and found that, across individual sports including track-running and swimming, male athletes gained 4.5-6.3 years of life and women lived 3.9 years longer than average. The lead author, professor Les Mayhew, noted that \u201cthe longevity of distance runners is marginally higher than [that for] those who run other distances\u201d. <\/p>\n Then came a study published last year that looked at the first 200 male athletes to run a sub-four-minute mile. It showed that these elite runners typically lived about five years longer than average, which, said the researchers from Australia and the University of Alberta in Canada, \u201cchallenges the notion that extreme endurance exercise may be detrimental to longevity\u201d.<\/p>\n \u2022 Is your heart healthy? How to protect it at every age<\/a><\/p>\n Even many competitors in the gruelling Tour de France appear to have enhanced longevity. Researchers at the University of Valencia compared the longevity of 834 cyclists who took part in the three-week cycling race between 1930 and 1964 and found that the age at which 50 per cent of them died was 81.5 years, compared with 73.5 years for 50 per cent of the general population.<\/p>\n As Van Puyvelde points out, the effort entailed in completing a single Tour de France<\/a> stage can cost cyclists about 35,000 extra heartbeats, but results in improved cardiac efficiency. \u201cWhat\u2019s really happening is more of a push\/pull scenario in which you do \u2018spend\u2019 more of a heartbeat budget during physical exertion, but you also \u2018save\u2019 more of them in the long term.\u201d <\/p>\n Van Puyvelde says his research findings strengthen the argument for keeping tabs on your daily heartbeat. He says it could function as \u201ca simple but all-encompassing metric of metabolism that could help to determine exercise doses\u201d as fitness levels increase. Knowing your heartbeat budget may also help to highlight when you are stressed or tired. <\/p>\n \u201cIt could act as a sort of safety signal telling you when you maybe need to be a bit more active or if you need to slow down,\u201d Brownlee says. \u201cYour health and longevity depend not on how many times your heart beats in your lifetime, but how well you spend each heartbeat.\u201d<\/p>\n It is already possible to measure our heart rate \u2014 the number of beats per minute \u2014 using a fitness tracker, Van Puyvelde says, and he \u201cwouldn\u2019t be surprised\u201d if manufacturers soon have us counting heartbeats as we do steps. \u201cThe data is already there,\u201d he says. \u201cIt\u2019s just a matter of packaging it and then it\u2019s an easy concept to help understand how your lifestyle impacts your heart and metabolic efficiency over time.\u201d<\/p>\n \u2022 How fit are you really? Three easy tests you can do at home<\/a><\/p>\n What you need to know about your heart healthYour heart will beat about 2.5 billion times during your lifetime<\/p>\n \u201cRough maths suggests an average person\u2019s heart beats about 70 times per minute, which equates to 100,000 a day,\u201d Brownlee says. \u201cBut your total number of heartbeats is individual to you and influenced by your lifestyle habits and how fit or stressed you are.\u201d The precise speed of the pumping action is controlled by your heart\u2019s electrical system, which signals how fast and hard to beat in response to physical and emotional demands. <\/p>\n Calculate your maximum heart rate by subtracting your age from 220<\/p>\n This provides a rough estimate that\u2019s within about ten beats of reality for most people, \u201cso good enough for general guidance\u201d, Brownlee says. \u201cThere are newer formulas, such as 208 minus 0.7 times your age, which is a little more accurate, especially for older adults.\u201d<\/p>\n You can work out at a high intensity whatever your age<\/p>\n \u201cIt\u2019s perfectly safe to work up to 80-90 per cent of your maximum heart rate in midlife or later, provided you\u2019re used to exercising at that intensity and don\u2019t have symptoms or medical restrictions,\u201d Brownlee says. \u201cThe heart, like any muscle, adapts to challenge and pushing into higher training zones keeps your cardiovascular system responsive and your fitness from sliding.\u201d<\/p>\n