You shouldn't be creepily ogling the gym baddies anyway no matter what you're on. Tadalafil is perfectly fine in the gym or the sauna as long as you control where your attention goes.
Another thing is that overtime your body adjusts to the side effects. I used to get headaches or stuffy nose, those are gone now.
In any case, always take medication under the guidance of a doctor and don't mess with the dosage!
My sentence was never about "use Taladafil to get stronger in the Gym" but more about "do not drop it before you are going to the Gym" ;-)
Apart from that: Effects after Taladafil on your "back pain reception" my be included, as it has an effect on especially skeleton muscles etc.