Agile

A G I L E ag - ile pronunciation:  definition: quick, nimble, light on your feet,

synonyms: adroit, artful, clean, clever, dexterous, nimble, slick, spry

Mobile, agile, hostile! -From //Remember the Titans//

All these three seem to indicate a force or an ability. In context with the movie, they repeated this phrase over and over because they needed to be mobile, agile, and hostile. If you aren't agile, or able to move with quick reflexes, the opposing team would tackle you every time.