When using the attack action with a melee weapon, you can split your move action
in that round in order to move both before and after the attack, provided that your total distance moved is not greater than your speed. Moving in this way does not provoke an attack of opportunity from the defender you attack, though it might provoke attacks of opportunity from other creatures, if appropriate. You can't use this feat if you are wearing heavy armor.
You must move at least 5 feet both before and after you make your attack in order to utilize the benefits of Spring Attack.