I might as well explain how things work for people who are confused. (right now no one lol)

Every 60th of a second, your energy goes down, by a little bit.

This "little bit" is increased every time you sprint, and will go back to normal after a few seconds. 

The lower the energy you currently have, the faster this goes back to normal. The higher the energy you have,  

the slower it takes for it to change back to normal.

One more thing:

Energy affects:

-Cooldown between sprints (how long you have to wait each time you sprint before you can sprint again)

-Speed of sprint (How fast you sprint)

It does NOT affect:

-Move speed

-Health

That's all for sprinting!