It attacks the heart, weakening its muscles and disrupting its critical rhythm.

weeeeeeeeeeeeeeeeell I would dispute the contention that we would not expect it to affect any of our muscles. Ask anyone who had ME/Yuppy 'flu/Chronic Fatigue Syndrome. The virus (Epstein Barr, Cocksackie B, etc) lives in the muscles and every time you get a cold the muscles weaken. It re-awakens the virus. FWIW Glandular Fever is a manifestation of the Epstein Barr virus and that is a chronic condition.

In the 80s, my doctor thought it was psychological, I insisted on a second opinion, I had the tests, and the specialist said "you had a virus". "Which one?" says I. "We don't know".

Thanks - but that is what I told the bloody doctor in the first place.
3 years later I saw a TV prog and my evidence fitted about ½ of all symptoms. In a syndrome you don't get them all.

My solution at the time was to fight it, eg run up stairs and get the pain at the top, not on each step. Apparently fighting psychologically is deemed a good methodology. But how fit would I be now without that burden? Who knows, you habituate to the new norm, like a poorer short term memory. It is what it is.