Every season of The Flash, the CW TV series, finds our eponymous hero facing a villain that is faster than him. In order to defeat them, he needs to run even faster. So, how fast is that?
In the comics, it is widely accepted that Barry Allen has the ability to run up to two times the speed of sound. However, the televised version of the character, played by Grant Gustin, isn't even close to those limits. He's able to go much faster than that in the show thanks to his connection to The Speed Force.
The Speed Force is a mysterious energy field that gives the Flash his superhuman speed. He taps into it while running, and this allows him to exceed his own limits. This is how he can travel so quickly in the Arrowverse and breach universes.
When the Flash runs at such a high speed, it causes time to slow down for everyone around him. This is why you see the trailing lightning bolts whenever he speeds up.
If you were to try and run at speeds approaching light speed, the math tells us that your mass would increase and your length would contract. Essentially, you'd be everywhere and nowhere at the same time.
While it is impossible for a human to run as fast as the Flash, there are plenty of other ways that you can get your body moving at an elite level. One popular method is the 60/120s method, which involves sprinting for sixty seconds and then jogging or walking for 120 seconds as a recovery. This allows you to use a higher work to rest ratio, which can help improve your overall running speed.
