It is well known that regular exercise is one of the most beneficial things we can do to optimise our heart health. Increasing the amount of exercise to the recommended minimum of 30 minutes a day, at least five days per week has been demonstrated to reduce the risk of developing heart disease, including lowering the risk of suffering a heart attack. Beyond this, regular exercise can also prevent and help manage many other conditions, including some cancers, high blood pressure and type 2 diabetes. However, the right amount of exercise for optimal heart health has been long-debated, and in fact some previous studies have suggested that too much exercise may in fact even be detrimental to the heart. So, is there such thing as too much exercise, and how much exercise do we need to do for better heart health?
The recent publication of a large population-based cohort study has helped answer this question. This study reached its conclusions based on objective data about exercise from more than 90,000 adults who wore an accelerometer (personal activity tracker) – a small lightweight motion sensor that more reliably measure physical activity status than self-reported questionnaires, which is what most of our previous understanding of the associations between exercise and heart disease were based on. The results of this study showed that almost any amount of physical activity seems to be good for heart health, with no apparent upper limit to the benefits. The study found that people who exercise regularly and stay active are much less likely to develop heart disease than people who move very little, whether that exercise consists of a few minutes a day of jogging or many hours a week of walking.
This is important new information, as some older studies have shown that as the amount and intensity of people’s exercise increased, the heart health benefits plateaued or even worsened. In fact, some previous studies have even suggested that prolonged intense workouts over many years may have contributed to a paradoxical increased risk for heart disease, suggesting that too much exercise may be harmful to the heart. However, these older studies generally only sampled small numbers of people and focused on specific groups, such as veteran male athletes.
The results of this new study come from the U.K. Biobank, which is a large database of health and lifestyle information about more than 500,000 adult men and women in the United Kingdom that was established in 2006. This Biobank has collected blood, urine and saliva samples for genetic and biochemical testing, as well as comprehensive health and medical screening examinations from the participants. More than 100,000 of the Biobank participants also agreed to wear personal activity trackers for a week to accurately measure how much physical activity they undertook. After excluding the participants with known heart disease when they joined the study, 90,211 were included in this study who were then divided them into four quartiles or groups, depending on how many minutes they exercised every week, and how much of this activity was moderate (e.g. walking), or vigorous (e.g. jogging), as verified by their personal activity trackers. Finally, the researchers collected data about who developed heart disease in the years after joining the study, and crosschecked their diagnoses against the exercise habits of the participants.
As we would all have expected, the results of the study found that being physically active was protective against heart disease, with individuals who engaged in higher levels of physical activity having lower risk for heart disease throughout the range of physical activity measured. People who were least active, in other words who rarely walked and did not formally exercise, were more than twice as likely to develop heart disease as the most-active participants. By moving a little more than the minimum, the second lowest quartile group reduced their risk of heart disease by almost 30 percent, even when other factors were controlled for including body fat, smoking and socioeconomic status. The researchers also found no upper limit to the benefits of exercise. In other words, the lowest risk for heart disease was seen at the highest levels of physical activity, whether total activity, moderate-intensity activity, or vigorous-intensity activity was measured. This highest quartile group comprised men and women who walked more than two hours a day (including both their actual exercise and everyday activities like shopping or housework), as well as worked out intensely for at least 50 minutes a week. Both men and women showed roughly equal benefits to high level exercise.
My view is that these results of this study are reassuring, however not surprising as the benefits of exercise have long been well understood. However, the study is important in adding to our knowledge base as it provides the strongest available evidence of the association between physical activity (including vigorous exercise) and lower cardiovascular disease risk. In fact, the study demonstrates that the benefits of exercise are approximately double what we had thought based on most previous studies that self-reported levels of physical activity. The only caveat I would add to the results of this study is that the number of participants who undertook extremely high amounts of intense activity was small, so it remains possible that long-term, very intense exercise might, at some point, be detrimental to heart health. This is something that requires more study. But for the majority of us, increasing our levels of exercise to more vigorous levels of 1-2 hours per day will almost certainly substantially reduce our future risk for developing heart disease. Therefore, my advice to patients regarding the right amount of exercise is: “the more the better, but at least 30 minutes a day on most days of the week”
As I have written about before, do not forget that exercise is only one aspect we need to pay attention to minimise our risk of heart disease – we must not forget a heart healthy diet, avoiding smoking, adequate sleep, managing stress, limiting alcohol consumption and regular heart health checks with our GP.
For practical tips on how to get started or increase your levels of exercise and physical activity, please see the following useful information provided by the National Heart Foundation:
https://www.heartfoundation.org.au/heart-health-education/physical-activity-and-exercise
Reference:Accelerometer measured physical activity and the incidence of cardiovascular disease: Evidence from the UK Biobank cohort study.PLoS Med 2021; 18(1): e1003487. R Ramakrishnan, A Doherty, K Smith-Byrne et al.
