Interactive Forum August 2010: Andy Murray Serve And Forehand: High Speed in High Def

[uspta146749877]

Why?

Why would that be? What do John and Brian think?

Look at the equation v=sqrt( vx*vx + vy*vy+vz*vz)
It seems to me that vz is increased when pronation is increased
but vx and vy are diminished when pronation is increased.
What a speed gun measures is a bit different issue

[uspta146749877]

Biomechanics of a left hand

I've never quite liked the way Murray throws his left arm out behind him at the end of the serve. I find it slightly more exaggerated than with other players on the tour. On occasions he almost flings it out in! Funny this because as a kid it was a problem that seem to get rectified somewhere along the way by his coach...but the trait still rears its head again now and then.

I know this because I am English and was coaching a kid that played the same junior circuit here in the uk. They used to have good games back then. My kid levelled off while Andy went on to stardom. My kid now has a mundane job in a bank while Andy is a multi millionaire and a national hero...funny how life pans out...

Another thing you might be interested to hear is that Andy was very passive in his style of play as a junior too. He had to be almost forced into hitting aggressively. His preferred style was to rally well within himself and outmanoeuvre here and there. He always played it cagey on big points. It served him well here in the UK when he was a kid as standards weren't that high. Good job he moved to Spain!

Good to see overcome his instincts and playing so aggressively last week against Nadal and Federer. That's the Andy I like to see!

Lovely clip to look at and analyse....thanks

What is wrong with a movement of a left hand of Murray from the point of view of biomechanics?

[uspta146749877]

An article

Probably couple of last paragraphs of

http://www.tennisplayer.net/members/avancedtennis/john_yandell/sampras_serve/sampras_serve_racket_head_speed/sampras_serve_racket_head_speed.html

are of interest

[stotty]

When he was a kid he used to throw the left arm out at the end of the serve in an uncontrolled way...almost flung it out. It happens with some kids. Clearly it is now corrected and biomechanically the serve is sound. But every now and again he'll fling that left arm out just like he used to.

Ian Barclay once told me that some of the more stubborn technical problems that Pat Cash had as child would rear their head again sometimes in matches where was he under severe pressure. Maybe it's the same with Andy.

Maybe it's just me! Anyway, keep an eye out and see if you spot it sometimes.

[gzhpcu]

Look at the equation v=sqrt( vx*vx + vy*vy+vz*vz)
It seems to me that vz is increased when pronation is increased
but vx and vy are diminished when pronation is increased.
What a speed gun measures is a bit different issue

Could you please your use of the coordinates? For example, is X horizontal, Y vertical and Z forward? Also, it seems to me that the speed of the racket head will vary as a function of the angle between the racket shaft and the forearm at impact.

[uspta146749877]

A definition of coordinates

Could you please your use of the coordinates? For example, is X horizontal, Y vertical and Z forward? Also, it seems to me that the speed of the racket head will vary as a function of the angle between the racket shaft and the forearm at impact.

x and y in a plane being a surface of a court
z perpendicular to a surface of a court

[gzhpcu]

x and y in a plane being a surface of a court
z perpendicular to a surface of a court

Why is dz in particular increased with pronation? Just to explain, the way I understand pronation is that ultimately the racket faces the direction you want to hit the ball. The more you pronate, the longer the path of the racket in respect to forearm (the larger the angle traveled). Seems to me that it affects the forward direction as well, since it increases the whipping motion...

[uspta146749877]

Clarification

Why is dz in particular increased with pronation? Just to explain, the way I understand pronation is that ultimately the racket faces the direction you want to hit the ball. The more you pronate, the longer the path of the racket in respect to forearm (the larger the angle traveled). Seems to me that it affects the forward direction as well, since it increases the whipping motion...

I assume that that by dz ABOVE you mean vz ( which is a velocity of a ball
perpendicular to a surface of a court)
A height of a bounce is related to amount of pronation.
Generally more pronation produces more vertical component of a bounce
regards,

julian mielniczuk uspta certified pro juliantennis@comcast.net
www.julianmielniczuk.usptapro.com Courtside Tennis Club,Bedford,MA

[gzhpcu]

I assume that that by dz ABOVE you mean vz ( which is a velocity of a ball
perpendicular to a surface of a court)
regards,

julian mielniczuk uspta certified pro juliantennis@comcast.net
www.julianmielniczuk.usptapro.com Courtside Tennis Club,Bedford,MA

Right, I was thinking differentials...

[uspta146749877]

Addendum

A height of a bounce is related to amount of pronation.
Generally more pronation produces more vertical component of a bounce
regards,

julian mielniczuk uspta certified pro juliantennis@comcast.net
www.julianmielniczuk.usptapro.com Courtside Tennis Club,Bedford,MA

[uspta146749877]

A useful reference

A pronation/supination paragraph of

http://www.tennisplayer.net/members/biomechanics/brian_gordon/upward_swing_part_2/upward_swing_part_2.html

is of some interest as well
There are two basic problems in OUR USEFUL conversation:
1.is your definition of pronation the SAME as a defintion of Brian Gordon?
2.do we distinguish pronation BEFORE a contact vs pronation AFTER a contact?
3.can we compare a serve without pronation with a serve with pronation

[makhan67]

Looking at Andy Murray's serve action, I felt that he does one thing a bit different: As he finishes his stroke, his left arm/tossing arm does not stay at his mid-section, it fleshes out to his left; and I think this explains his double faults! I may be wrong.

[gzhpcu]

A height of a bounce is related to amount of pronation.
Generally more pronation produces more vertical component of a bounce
regards,

julian mielniczuk uspta certified pro juliantennis@comcast.net
www.julianmielniczuk.usptapro.com Courtside Tennis Club,Bedford,MA

Yes, you are right.

[gzhpcu]

A pronation/supination paragraph of

http://www.tennisplayer.net/members/biomechanics/brian_gordon/upward_swing_part_2/upward_swing_part_2.html

is of some interest as well
There are two basic problems in OUR USEFUL conversation:
1.is your definition of pronation the SAME as a defintion of Brian Gordon?
2.do we distinguish pronation BEFORE a contact vs pronation AFTER a contact?
3.can we compare a serve without pronation with a serve with pronation

Basically the rotation of the forearm, which according to Brian's article:

The fact is that much of the forearm rotation observed by coaches is due to shoulder internal rotation, and not independent forearm pronation.

So I am referring to the overall forearm rotation, both dependent and independent.

[llll]

just because murray does not get full pronation in his serves would you say thats bad???
against the compettioin he plays ie world class, he can serve into the 130's and can serve very effectively and can hit the targets and has a slice , flat and topspin serve. so even tho he doesnt have the look or "finish " of sampras or pancho it just goes to show what can be done without that look or finish (implying less pronation)
on the other hand
one could say "think how much better his serve would be if he did pronate more."

since this got overlooked please comment on this.