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,
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