That's not how this sort of analysis is done. They separated people by push-up capacity, and compared the rate of heart disease in the low-capacity group versu

That's not how this sort of analysis is done. They separated people by push-up capacity, and compared the rate of heart disease in the low-capacity group versus the high-capacity group; those rates were 36 "cardiovascular events" for the 948 low-capacity guys (so, 3.7% of them), and 1 for the 155 high-capacity guys (0.6% of them.) I know which group I'd rather be in. It is true that, with the small number of events, the precise "96% reduction" number shouldn't be taken too seriously- the study notes that the 95% confidence interval is 99% to 64%; essentially, there's a one-in-twenty chance that it's a 99% reduction, or likewise that it's only a 64% reduction. Science never grants absolute uncertainties- but sadly, that part never makes it into the news story.