On the track you are pulling an extra half g or so in the bankings depending on speed and turn radius. This might be contributing. Your 150lb body might weigh over 200lbs through the turns.
Also, do you have trouble standing during a race (some people do)? Just standing every once in a while usually makes any numbness go away.
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Cat 2 Track, Cat 3 Road.
"If you’re new enough [to racing] that you would ask such question, then i would hazard a guess that if you just made up a workout that sounded hard to do, and did it, you’d probably get faster." --
the tiniest sprinter