Elbow techniques
The elbow can be used in seven ways: horizontal, diagonal-upwards, diagonal-downwards, uppercut, downward, backward-spinning and flying. From the side it can be used as either a finishing move or as a way to cut the opponent's eyebrow so that blood might block his vision. The blood also raises the opponent's awareness of being hurt which could affect his performance. This is the most common way of using the elbow. The diagonal elbows are faster than the other forms, but are less powerful. The uppercut and flying elbows are the most powerful, but are slower and easier to avoid or block. The downward elbow is usually used as a finishing move.
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 first with an elbow follow-up. Such elbows, and most other elbows, 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
References :
Muay Thai The Most Distinguished Art of Fighting (Text-book of Pahuyuth) , Panya Kraitus and Dr. Pitisuk Kraitus, Third Edition, Special Revised, 1992, Panya Kraitus, Phuket, Thailand.
Muay Thai Kickboxing - The Ultimate Guide to Conditioning, Training and Fighting, Chad Boykin, 2002, Paladin Press, Boulder, Colorado.
Thai Kickboxing For Beginners - Peter Belmar, 2006, Lulu Press. Muay Thai: A Living Legacy - Kat Prayukvong, 2006, Spry Publishing Co., Ltd.
From Wikipedia
