Lockrings on the track

Do track racers use lockrings? Hipsters need them I guess, applying more reverse torque than forwards half the time, but are they required for racing?

Most racers don't use them, but they are often recommended for novice riders who might kick back on their first session.

If you are riding the track properly, you shouldn't need to kick back hard enough to unscrew a cog and in any case, once a cog has been "sprinted" on they don't tend to come undone easily!