If you're someone who's completely sedentary, then only a small amount of exercise is needed to see a reduction in cardiac risk. From a starting point of virtually zero exercise, an hour or two a week of leisurely cycling or brisk walking might be all you need to reduce your risk of death from cardiovascular disease by as much as 20 percent.
But as you get fitter and increase the amount you exercise, the cardiovascular health gains diminish and eventually plateau.
A sedentary person who goes from doing nothing to exercising a couple of hours a week will see the greatest reductions in cardiovascular risk during this period. If they increase the amount they exercise to four hours a week, there would be additional – albeit smaller – reductions in risk (around 10 percent). But the benefits to cardiovascular health appear to max out after four to six hours a week – with no additional gains beyond this point for everyone.
However, one study in which sedentary people were trained to complete an endurance event, such as a marathon, found that once participants reached seven to nine hours a week of training, they saw noticeable changes in their heart's structure.
Training at this level gives the same reductions in cardiovascular risk as training four to six hours a week. But participants had an increase in their amount of heart muscle, as well as dilation of their cardiac chambers. The heart is like any other muscle: if trained enough, it will get bigger. These changes occurred as early as three months after starting.
So, while the additional hours of exercise don't provide further benefit in terms of reducing cardiovascular disease risk, these changes in the heart's structure will mean improvements in fitness – and hopefully, running a faster marathon.
Four hours a week is the sweet spot that gives the greatest reduction in cardiovascular risk – but if you enjoy training or find a sport you love, you shouldn't let this stop you doing more.
Source: BBC
Bd-pratidin English/Fariha Nowshin Chinika
