Here's a quick review of the large studies which the article cites: [1] says that snowfall in Canada is correlated with heart attacks in men, but not in women.

Here's a quick review of the large studies which the article cites: [1] says that snowfall in Canada is correlated with heart attacks in men, but not in women. Shoveling is just a postulated cause. [2] reports the proportions of different types of snow shoveling injuries in people treated in US hospital emergency departments. I did not find any statements in [2] to support the article's statement that "of the patients with heart attack after shoveling snow, 80 per cent were men." Perhaps the article's author had access to this data or read this result elsewhere. [2] did say that 6.7% of the snow shoveling injuries were cardiac-related. 0.8% of the injuries were fatal; all fatal injuries were cardiac-related. Regarding gender as a risk factor, [2] did report that in patients age ≥ 55 years, males were twice as likely as females to have their injury be cardiac-related. This suggests that being old and male does confer extra risk of snow shoveling-related heart attack. Note that [2] cites work saying that cold temperatures alone, even absent physical exertion, are associated with heart attack in at-risk patients. Cold temperature, independent of snow shoveling, could therefore be a cause for the results in [1]. [1] http://www.cmaj.ca/content/189/6/E235 http://www.cmaj.ca/content/189/6/E235 [2] http://www.sciencedirect.com/science/article/pii/S0735675709003714 http://www.sciencedirect.com/science/article/pii/S0735675709...