cartwheel motion in serve

[taurussable]

for platform stance, is it mainly generated by the push up of back leg?

 

[Topspin Shot]

Good question. I'm going to say no as you can cartwheel properly without using any legs at all, e.g. a wheelchair player.

 

[Chas Tennis]

See pages 8 and 10 of this presentation.
http://www.spalla.it/handout/2012_aprile/ELLIOTT_Biom_of_serve_Italy_20_m.pdf

A good book covering the subject of the 'cartwheel' and other service motions is Biomechanics of Advanced Tennis.

Perhaps Bahamonde introduced the term "cartwheel"? He is usually referenced. But his 2000 publication is not available except at high cost, $40, or free if you are a student and your library happens to have a journal subscription.
http://www.ncbi.nlm.nih.gov/pubmed/10972409
http://www.science.gov/scigov/result-list/fullRecord:Bahamonde+2000+tennis+serve/

However, I have seen some surprisingly minimal, relaxed looking activity of the back leg in some high speed videos, so double check the part played by the back leg. Does the back leg have a dominant role? Always? Mostly? Variation among servers?

 

[taurussable]

for wheelchair or pinpoint servers they may use a different mechanics cartwheel the shoulder over.

tried shadow serve with only left foot, it feels much harder to cartwheel without right leg.

 

[Chas Tennis]

Peter Norfolk 'Quadfather' Wheelchair Tennis - Serve - at about 20 sec.
https://www.youtube.com/watch?v=0tzOVTfzQ0k

This server seems to point his chest up and rapidly come up & forward. Equivalent to the Somersault or trunk twist motions of the serve. ?

There are some shoulder height changes that are limited because the pelvis isn't tilting.

The shoulder girdle itself can tilt independently of the spine. Try it. Down a little but up more because of the scapular motion. Maybe still be a factor?

Google: range of motion shoulder girdle images.

See Also Thread - Kneeling servers hitting 125 MPH - really?
http://tt.tennis-warehouse.com/showthread.php?t=414039

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This video has some double exposure frames. This is an artifact because of interlacing or Youtube processing. Also, the original video may have been at 25 fps and has been processed to play at 30 fps. Double images are easy to interpret if objects move in one direction, as for this serve.
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Slow motion capture of a serve from Peter Norfolk. Peter is British and World No.1 in wheelchair tennis. Peter has been nicknamed 'The Quadfather'. Peter won a Gold and Silver medal in Athens 2004 and a Gold and Bronze in Beijing. Peter is a partner of EPC Wheelchairs, specialists in lightweight wheelchairs and sports equipment for the disabled as well as a successful athlete.

Frame #1 This is similar to the trophy position, the forearm and racket are in position to pre-stretch muscles including externally rotating the shoulder.

Frame #2 Double image of arm and racket as described above. The first position appears to be the same as frame#1. In the second image, the forearm has rotated back because of a forward motion of the shoulder or active shoulder external rotation by muscle. This motion is pre-stretching the internal shoulder rotator muscles and/or other muscles. The elbow appears to be moving forward, the racket backward and the hand is not moving very much - a rotation around the hand? Lag?

Frame #3 The elbow and forearm have moved forward and the racket has lagged farther back. This frame is about the most cocked position caught in this video.

Frame #4 The arm is straight and the racket is edge on to the ball. The shoulder is high. The upper body is turning, compare to Frame #1. This is close to the Big L (searchable term) that we have posted often.

 

[Chas Tennis]

Frame #5 Double image as described above. This shows the racket before impact and faintly after impact. The arm is near straight. The racket looks edge-on to the ball in the first image. I can't tell a lot about the ISR or know what ISR on high level wheelchair serves should look like.

Frame#6 - I believe this racket position is the same one as the second faint image in Frame #5. It shows the forearm-racket angle at impact. Unfortunately, I'm more familiar with looking for angles along the ball's trajectory. Is that enough forearm-racket angle near impact and how much ISR was used?

 

[Ash_Smith]

Pete is perhaps not the best model to use for this discussion due to the level of his impairment - more relevant might be someone like Stephane Houdet, who has no impairment to upper body function (although it is great to see Pete recognised on here).

http://m.youtube.com/watch?v=bknn6RjwgOA&list=PLCGFN6Q8x7_LmHjrjBkb9ct6F-HnluvZe