A study recently published in the British Journal of Sports Medicine showed that to achieve a "significant reduction" in the risk of cardiovascular events such as myocardial infarction and stroke, adults need about 560 to 610 minutes of moderate-to-vigorous physical activity per week, which is about three to four times the 150 minutes recommended by current public health guidelines. The research team noted that existing one-size-fits-all exercise recommendations may underestimate the amount of exercise needed to truly bring about substantial risk reductions.
Current public health guidelines from many countries recommend that adults engage in at least 150 minutes of moderate-intensity aerobic exercise, such as brisk walking, jogging or cycling, per week to protect cardiovascular health. However, the study found that at this level, participants only achieved a modest reduction in cardiovascular risk of about 8% to 9%, and to achieve a relative risk reduction of more than 30%, they would need to increase the duration of moderate-to-high-intensity exercise to 560 to 610 minutes per week. Only about 12% of those monitored met this higher level of physical activity.
The study, led by researchers from the Macau Polytechnic University in China, used data from the UK Biobank cohort to analyze the association between physical activity, cardiorespiratory fitness and cardiovascular disease risk. The study included 17,088 participants between 2013 and 2015, with an average age of 57, 56% were female and 96% were white. Participants wore a wrist-worn device for seven consecutive days to record daily moderate to high-intensity activity levels and to estimate maximum oxygen uptake (VO2 max) through cycling power testing as an indicator of cardiorespiratory fitness.
The research team also collected information on smoking and drinking habits, self-reported health status and diet, body mass index, resting heart rate, and blood pressure to control for potential confounders. During an average follow-up period of 7.8 years, a total of 1,233 cardiovascular events were recorded, including 874 atrial fibrillation, 156 myocardial infarction, 111 heart failure, and 92 stroke. Researchers evaluated the nonlinear dose-response relationship between different levels of exercise and cardiorespiratory fitness and the risk of cardiovascular events.
The analysis results show that people who meet the "guideline standards" of moderate to high-intensity exercise for about 150 minutes per week, regardless of their cardiopulmonary fitness, only have a small decrease in cardiovascular disease risk of about 8% to 9%. In contrast, increasing exercise time to 560 to 610 minutes per week was associated with a significant reduction in the risk of cardiovascular events of more than 30%. The researchers pointed out that this result shows that to achieve "substantial" cardiovascular protection, many adults may need an amount of exercise that far exceeds the "minimum threshold" in the past.
Notably, interindividual differences in cardiorespiratory fitness play an important role in this relationship. Research shows that people with poor cardiorespiratory fitness need to devote more time to moderate to high-intensity activity than those with high fitness to achieve similar levels of risk reduction. For example, when trying to reduce cardiovascular risk by about 20%, the low-fitness group needed about 370 minutes of moderate-to-high-intensity exercise per week, while the high-fitness group needed about 340 minutes, a difference of about 30 minutes.
The researchers pointed out in the paper that this finding highlights the challenges faced by "defitted" people, who often require greater exercise investment to make up for the lack of basic cardiopulmonary function. For this reason, the author believes that it is necessary for future exercise guidelines to shift from "one-size-fits-all" uniform duration requirements to more individualized goal setting, taking into account personal cardiorespiratory fitness levels.
From a mechanism perspective, cardiorespiratory fitness (usually estimated through maximum oxygen uptake VO2 max) is one of the key indicators of cardiovascular health, reflecting the ability of the heart, lungs and muscles to absorb and utilize oxygen during strenuous exercise. A large number of previous studies have confirmed that low cardiorespiratory fitness is closely related to an increased risk of myocardial infarction, stroke, and premature death. This study further uses the exercise volume and VO2 max data measured by the device to construct a more refined exercise dose and risk curve, providing a data basis for public health recommendations.
However, as an observational study, the authors also emphasized that these results cannot prove causation, but only suggest correlation. In addition, UK Biobank participants may be generally healthier and more concerned about their condition than the general population, which to a certain extent limits the generalizability of the results to the wider population. The study's use of estimates rather than direct measures of cardiorespiratory fitness and its failure to account for factors such as sedentary behavior and light physical activity were also cited as important limitations.
According to the research team, the current guideline of at least 150 minutes of moderate-intensity exercise per week is still a feasible and effective "basic safety line" for most adults, which can bring a certain degree of cardiovascular protection. But for highly motivated people who want greater improvements in cardiovascular risk, future recommendations may make a clearer distinction between “minimum recommended amounts” and “optimally protective amounts.” The authors concluded that future public health guidelines may need to draw a clear distinction between, on the one hand, the minimum amount of moderate-to-high-intensity exercise used to construct a basic margin of safety, and, on the other hand, the higher doses of exercise required to achieve “optimal” cardiovascular risk reduction.
The study is titled "Joint nonlinear dose-response relationships between device-measured physical activity and cardiorespiratory fitness and cardiovascular disease: a cohort and Mendelian randomization study" and has been published online in the British Journal of Sports Medicine. The paper uses UK Biobank data and combines Mendelian randomization analysis to further explore the potential causal link between exercise and fitness and cardiovascular risk.