Wrist rotation - An archery biomechanical magic trick.

Written by: Amchila
Posted: 28/10/2009

Try this. Starting with your arm by your side completely relaxed. Without introducing any tension into your forearm, wrist or hand, place your hand in the anchor position.

What’s this! The palm of your hand is pointing to the ground!

Now to get your fingers on the string, you have to rotate (supinate) your forearm, wrist and hand 90 degrees around the line of draw force axis. Feel the tension! If your forearm and wrist are relaxed that rotational tension is now on your string.

So you release. And with perfect relaxation. Wait on! What is that rotational tension doing to your release? And is that same rotation tension causing the little finger side of your hand (medial side) to flick out to the annoyance of your coach?

So is releasing perfect relaxation or not so perfect relaxation?

Eliminating rotational torsion tendency should make the archer’s technique more forgiving.

Any lower arm axial rotation (pronation and supination) can only come from the forearm as the fingers and wrist do not have any voluntary rotation capability. There can be some rotation involuntarily due to external forces being applied and stretching of soft tissues. Maybe this is analogous to the D loop in compound archery?

Now for the magic part with biceps biomechanics to the rescue.

But before biomechanics we need a little anatomy 101. The biceps is so named because it has two muscle bellies that are attached to bone at two origins up around the shoulder. But for archers that is not so important. What is important for archers is that it also has two insertions in the forearm. So biomechanics here we come.

It is common knowledge that the biceps muscle is used to flex the elbow joint. However when the elbow is flexed with the biceps muscle, there is also rotation of the forearm (supination – little finger side moving in). Try it yourself. Contract your biceps muscle and then rotate your forearm from side to side while feeling your biceps muscle. In Kee Sik Lee’s book there is an EMG of biceps muscle contraction showing that the top archers contract the biceps muscle at the time of release in order to keep the hand near the side of jaw and not flying away from the face as done by many beginners and not so beginners.

It would be interesting to have more exact timing of the release compared to muscle contraction and also EMG’s of other forearm/elbow muscles. But it would be rather elegant if the contraction one muscle controlled both rotation and lateral movement around the draw force axis thus keeping other muscle involvement in releasing to a minimum.

So that draw hand follow through takes on more significance.

Okay. Hands up. Who actually read all of that?

Amchila 

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