Sprinting

Sprinting is a feature in Beta 1.8, which allows the player to run two times faster than walking. The player sprints by double tapping the "Forward movement" key which is (default) and then holding it. It will be possible to jump across four blocks horizontally (instead of the usual two blocks) by sprinting, however the jump will be no higher than normal.

Sprinting is unlimited as long as the Food Bar is above 30%, but it will also deplete the bar at a rate of 1 "meat" every 10 seconds. When a player sprints, particles will come from the player's feet. When a player hits any passive animal (excluding squid), the mob will fly back.

Sprinting stops when you run into a block or doing a sneaking action such as parrying with a sword. You do not stop sprinting when you run into a mob. Also, the player will not be ignited when you run through up to four consecutive blocks of fire (the fifth block will ignite the player). It is possible to make turns while sprinting without leaving the sprinting state of the player, thus altering the direction of where you go.

After switching in the "sprinting state" the field of view also slightly changes and the camera moves back to give the player more view of the terrain. If you turn the FOV to the max and sprint, when you look down, it appears as if the player is above ground.

Bugs
Sprinting while your food bar is above maximum does not deplete your food bar