There are 2 (at least 2) epidemiologic studies that indicate a linear dose-response relationship between physical activity (PA) and the risk of heart failure. While one study ( Pandy et al see below) does demonstrate a "modest" reduction in HF risk at a lower levels of PA, both studies how a more robust reduction in HF at higher exercise levels.
Pandy et al (Circulation 2015,, see ref 1 below) did a meta-analysis involving about 370 thousand subjects , 20 thousand of which developed HF over a 13 years period.They compared the HF risk in 3 categories based on level of exercise, namely 500 MET-min per week ,1000 MET-min per week and 2000 MET-min per week.
500 MET-min per week is equivalent to 2.5 hours of "moderate" exercise per week or 1.25 hours of "vigorous" exercise per week.Moderate is defined a exercise requiring 3-5.9 MET and vigorous as about 7 METS. (It requires about7 METS to run a 15 minute mile or to finish Stage 2 on the Bruce protocol treadmill exercise tests. One should be able to walk a fifteen minute with a 02 consumption of 5 METS.)
1000 MET-hrs per week is 5 hours of moderate or 2.5 hours of vigorous exercise per week and 2000 as twice that or 10 hours of moderate exercise per week. Yes, that does seem like a lot,
Both the 2008 US exercise guidelines and the 2018 guidelines recommend at least 500 but state that more benefits accrue with higher levels .
Pandy reported a linear,dose response with a "marked reduction in risk at very high doses of PA ( about 35%) at 2000 MET-min per week".
exercise level HF RF
500 MET hrs per week 0.9 (0.87-0.92)
1000 " " " " " " " " " 0.81(0.77-0.80
2000 " " " "" """"" 0.65 (0.58-0.73)
Quoting the authors; "Only a moderate reduction ( about 10%) risk in HF noted at the minimal ( US guidelines) recommended level,"
The authors offer a mechanistic explanation namely that CAD event risk occurs at a lower level of exercise by reducing the usual suspect Risk factors (BP,Lipids,blood sugar control) while HF risk reduction occurs at a higher levels of exercise perhaps by altering cardiac function and structure, i.e beneficial remodeling.
An earlier article Patel K, (Int J Cardiol 2013 see ref 2) had reached generally similar conclusions regarding the levels of exercise needed to decrease HR risk versus the amount adequate to reduce general CV risk, e m.gyocardial infarction.
Patel et al studied 5503 patients age 65 and older
During the 13 years of follow up incident HF developed in:
26% of those with little or no regular exercise
23% of those with "low"level of exercise
20% of those with "moderate"
19 % of those with high .
Low was defined a 1-499 Met-min per week
medium as 500-99
high as greater than 1000