As I have been told (by a doctor) when you get sick, your heart pumps harder to help pump blood around the body quicker. When you the exert yourself through exercise this puts even more strain on your heart but the pericardium (sack around the heart) does not expand. This can lead to a condition called myocarditis and this is what can cause a heart attack. Bottom line, take a few days off, get better and give the poor legs a break too. Muscle has amazing memory andyour fitness will come back quick enough. Hey, even Bradley Wiggins took some time out to get better!
