An argument can be made that an athlete taking himself to the limits puts them at greater risk of heart complications...
But then you must remember that the same athletes regularly did the same before taking the jab and weren’t falling dead on the field..so there’s that.
So why does it seem to target male athletes?
Well, there are some indications that androgen receptors factor into covid and vaccine risk. Frontline Doctors added some androgen receptor blocking meds to their lists and others have been noting a connection..it’s not a stretch to consider that athletes just might possess a greater number of androgen receptors and/or they may have a greater reaction to androgens.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363620/
This bit from the NIH article is explanatory.