There is also a distinct difference between a single elbow and a follow-up elbow. The single elbow is an elbow move independent from any other move, whereas a follow-up elbow is the second strike from the same arm, being a hook or straight punch first with an elbow follow-up. Such elbows, and most other elbow strikes, are used when the distance between fighters becomes too small and there is too little space to throw a hook at the opponent's head. Elbows can also be utilized to great effect as blocks or defenses against, for example, spring knees, side body knees, body kicks or punches. When well connected, an elbow strike can cause serious damage to the opponent, including cuts or even a knockout.