system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] Is there truth to the rumour that, if Flash went fast enough, he'd accelerate his ageing process?
gpt
No. He's gone faster than the speed of light, broken the barrier of speed itself, and run past the end of the universe. He still looks mid-twenties.

He'd age if there were some outside influences, but not from running alone. Besides, IIRC, one of the reasons Jay is still alive and active is because the Speed Force helps slow his aging.