The "no sex before a game" theory for athletes is TOTAL BS ... so says former NFL superstar Ottis Anderson -- who tells TMZ Sports, he wasn't exactly celibate back when he won Super Bowl MVP.
The St. Louis Cardinals all-time leading rusher was being herded around NYC today ... when we asked him if abstaining from sex before games actually gives you a noticeable testosterone boost.
Ottis -- who also played for the NY Giants -- tells us he thinks it's a complete myth that dumb people are buying into ... and encouraged athletes to bang away.
Check out the clip -- Anderson's a living legend ... and hilarious.
Ex-NFL Star Ottis Anderson
Busts Pre-Game Sex Myth
Banging Won't Slow You Down
1/29/2014 12:57 PM PST BY TMZ STAFF