That's silly. A whole season? I ran a number of my PRs (and a fair number of workouts, good, decent, or bad) directly/shortly/the morning after sex. Ran a few lousy races afterwards too, to be fair.
Granted, I know a guy who would go long stretches before championship races without sex, alcohol, or masturbation. Said it make him so angry and on edge that the focus came easy and he hated everyone enough to tough it out. It won him our Region in Cross Country one year, too.