Physical activity has been shown to reduce mortality in a dose/response manner, just like any drug. But many still wonder: are there any minimal requirements in terms of amount or intensity? Is there such a thing as “toxic exercise”? And finally, is exercising equally beneficial to all?
This study, conducted by Dr Sang-Woo Jeong from the Cardiovascular Department of Seoul National University, published in the European Heart Journal, answers all these concerns.
The current guidelines recommend between 500 and 1000 metabolic units (METs) minutes per week of regular physical activity. This is the same as telling our patients they can drink 20 gr of absolute alcohol per day. Patients stare back at us clueless, wondering the same we do. They want to know how many pints of beer, glasses of wine or whiskeys they can drink safely. It happens the same with exercise.
Light physical activity (such as leisurely walking or strolling) equals 2.9 METS; moderate physical activity (brisk walking, cycling or playing tennis doubles) equals 4 METS; and intense physical activity (running, cycling faster than 15 km/h, walking uphill fast or doing aerobics) equals 7 METS.
Once identified, MET values should be multiplied by minutes per day and number of days a week the patient exercises (e.g. brisk walking for 40 minutes 4 days a week equals 640 MET minutes per week). A complete sedentary lifestyle equals 0 MET minutes/week.
This study included 131,558 individuals with cardiovascular disease and 310,240 individuals with no known cardiovascular disease followed for mean 5.9 years with all cause death as end point.
There was an inverse correlation between physical activity and mortality in both populations. However, those with a history of cardiovascular disease (CVD) saw greater benefits from the same level of exercise than the ones with no history of CVD. For every 500 MET minutes per week of physical activity, there was a 14% reduction in mortality in patients with a history of CVD vs. 7% in patients with no history of CVD (p<0.001). In other words, the benefit of exercising is twice as high in the context of secondary prevention vs primary prevention.
For patients with no history of CVD, one “dose” of exercise between 1 and 500 MET minutes per week seems enough, but individuals with CVD continue to benefit from 500 METS, even 1000 or more MET minutes per week.
Adjusted mortality for CVD patients doing intense physical activity (>1000 MET minutes/week) is comparable and even lower than the group with no known CVD. This study tells us that CVD patient prognosis can be neutralized with regular exercise. Seeing as the cost/benefit ratio of exercising is still underestimated, it is without question essential to our consultation.
Original Title: Mortality reduction with physical activity in patients with and without cardiovascular disease.
Reference: Sang-Woo Jeong et al. European Heart Journal (2019) 40, 3547–3555.
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