These libraries allow you to change player's running (not sprinting) and walking styles. It means if you apply a walking/running style to a player, instead of classic walking/running behaviour taken from skin player is using, it will apply an animation to manipulate with player's motion.

More on: 

Mergevos/samp-walking-styles: Ben Jackster's walking styles script, forked by me, allowing player to choose between 15 walking styles (github.com)

Mergevos/samp-running-styles: Run in your style! (github.com)