What should be the values of the following 3 angles at the 4 positions described below during a forehand overhead power stroke (non-sliced)? The angles of interest: Angle of pronation or supination with respect to neutral position Angle of wrist flexion or extension with respect to neutral position Angle of radial or ulnar deviation with respect to neutral position For a graphical descriptions of these angles, see http://www.niehs.nih.gov/odhsb/ergoguid/chapv.htm (scroll down a little bit). The positions of interest: Preparation When the racket head is at the lowest point behind (below racket shoulder) Just before impact At the end of the snap or the sudden twist (not the end of follow-through) To avoid misunderstanding, it would be good if you can make your replies concrete and quantative. For example, Position 4: 80 degree pronation from neutral, 10 degree flexion, 20 degree ulnar deviation It would also be interesting to know if you generally describe this arm movement as a wrist snap or a forearm twist or something else.
The small movements of forearm and wrist are important for technique IMHO, but are too hard to see when watching a slow-motion video. So, I am trying an alternative approach to understanding them. I want to know about the "posture" of the forearm and wrist during the various phases of a full-power forehand overhead stroke. Posture as described by the angles formed at the wrist/forearm (shown in the images below) Let us pick one phase/position of the stroke (say, the preparation phase). Should your wrist be flexed or extended or neutral? Should there be any radial or ulnar deviation? Should the forearm be pronated or supinated or neutral? In each case, to what extent? (preferably described as the angle measured in degrees) Do the same for the other phases. Hope this is clearer then the opening post.
the wrist is limited, thats why i say for hard hitting strokes avoid to overwork your wrist and utilize more arm swing, because I sprained my wrist after abusing it for nearly every stroke
1 pronation 45, ?, ? 2 supination 90, ?, ? 3 pronation 0, ?, ? 4 pronation 90, ?, ? ?=don't know, but I expect zero would be close for all of them. The important thing when buying a house, err, doing a power shot is pronation, pronation, pronation.
Very good thread, I was just thinking to myself yesterday whether or not I get enough supination into my smashes, and whether it is limiting my power if I am not. Like Neil mentioned, I watched my forearm action during a mock smash, and it seems to supine 90 degrees. Should I be making a concious effort to supine beyond this angle, so that when the racket is brough behind the back, it would flare out to the side as opposed to downwards? This doesn't seem to be the answer though, as it looks like pro players' rackets are also behind their backs and pointing downwards at the lowest point of the swing. Maybe I am overlooking the point when the elbow comes up as the smash is unleashed, this seems to further supine my forearm...
I doubt that there's much (if any) quantitative on this. I remember doing a similar search for joint angles in baseball hitting, and I found some stuff, but for a sport like badminton I imagine there'd be much less info. One thing to consider is that physical attributes such as the distances between joints, and the ratio of tendon to muscle can affect the relative contributions of the different articulations, as well how much energy is from elastic transfer versus muscular contraction. In effect, the data would vary for each individual athlete. From a coaching standpoint, for technique development beyond the basics involves getting the student to understand the principles involved in making the shot (getting the desired contact angle, contact velocity, and getting to that velocity in as little time as possible) but to give them the freedom to self-optimize their movement. Basically, they'll be learning how to adjust their shots by feel.
I would say it looks more like: 1. Preparation: 0, 0, 0 (shoulder+elbow only) 2. End of backswing: 0, 0, 0 (shoulder+elbow only) 3. Before impact: pronation=90, flexion=0, ulnar=45 +/- 4. End of snap: pronation=135+, flexion=0, ulnar=45 +/- The point I want to make is that there must be some ulnar deviation since you usually want to hit the bird as high as possible, preferably above the right shoulder (if right-handed).
Pronation The forearm in neutral would be palm facing the body. Supination occurs when the forearm is rotated away from the body and thus pronation is towards the body. There is only a max of 90 degrees in either direction(some people may excede typically not to the 135 degree extreme) From a review of several videos and phots most of the top players appear to be at: Preparation: 0 pronation (neutral) Impact: 0 pronation (neutral) Follow thru: 90 pronation + 90 of shoulder internal rotation Dont forget the contribution of the shoulder in internal rotation that makes the pronation appear greater. jim
