If your hormones were natural, sex before the gym would have the potential to decrease your drive, strength motivation etc. It's all evolution - we all run on caveman software, still, and we are designed to hunt, kill (that's the gym), eat (that's your post workout meal) and then take your mate and procreate (sex). Messing with the order messes with you IF the hormonal and chemical cascades that facilitate said activities are left to their natural states. None of us allow our test levels to drop after sex, or allow an increased blockade of AR receptors in the brain after taking a mate, soooooo: fuck away, bro!