Some gym rats have ignored the conventional wisdom that exercising too much, too hard can have a detrimental effect on the immune system. (At least, the gym rats who concede that too-much-too-hard even exists.) The idea is that a tough workout creates an “open window” during which your body’s normal immune response, frayed from the stress you just put it through, is temporarily weakened, and unless you take the time to recover before the next session, that window stays open even longer. We all love our carefully-planned gym schedules, sure, but if you find yourself working out while sick, taking a swig of DayQuil before heading out the door and grimly blowing your nose in between heavy sets of deadlifts, at some point you have to ask: When is enough enough?
A team of researchers in Australia did your homework for you and have some science-based tips for perhaps sparing you from this hellacious, Kleenex-ridden cycle… More at GQ.
I suspect it would usually be better not to know ahead of time.