[Abagail]

You were doing good... I don't see the issue in what you need help with but here it is:

public OnPlayerKeyStateChange(playerid, newkeys, oldkeys)
{
if(PRESSED(KEY_SPRINT))
{
if(team[playerid] == TEAM_ZOMBIE)
{
ApplyAnimation(playerid,"MUSCULAR","MuscleSprint", 4.0,1,1,1,1,1);
}
}
}