The Sprint armor ability in Halo: Reach allows the player to lower their weapon and move at an increased speed for approximately 7 seconds . When you use the sprint ability you now pant heavily, and it can be heard by nearby players. Unlike Evade, Sprint can be used by the runner while he is still carring the bomb.
Sprint is a favorite among pure tanks and pure runners. The main advantage it grants tanks is in dancing. You can use sprint to quickly “dash” in between swings and hit the opponent before he can react. This sprint half-step is one of the main uses of sprint (besides to get from place to place quickly). You can also use sprint at any time while you’re ball running, unlike evade. It can provide the perfect speed boost to avoid enemies and make it to the plate. It’s also useful when trying to stiff-arm because you can quickly close the gap between yourself and the sword to get the punch. In that regard, how you use it is similar when tanking and running. Something also worth pointing out: With sprint, you have more control over where you’re going than you do with evade.