Archive

Archive for July, 2009

Tennis Tip: Hear Your Feet

July 31, 2009 Comments off

There are many variations of this general theme, one of which is the Tennis Channel’s one-minute clinic.  Imagine you are paid one dollar for every step taken to the ball.  If you are getting paid ‘by the step,’ the natural tendency is to take more steps to get to the ball.  Smaller steps is one of the keys to better footwork.  Hitting a moving ball requires a lot of fine adjustment from setup through the stroke and into recovery.  It’s easier to make those adjustments with the feet than compensating through upper body/arm/wrist manipulations.  Compensating for poor footwork robs you of power and accuracy.

So, how do you translate this to the court?  I’ve always liked tips that involve less thinking and more sensory feedback.  Even during a practice session, it’s hard to think about multiple things at once.  So, how do you tell if you are taking smaller steps to the ball?  Do you count them?

A variation of this general tip that I like is to ‘hear’ your feet during each stroke.  Especially on hardcourt, you can really hear small rapid steps and shuffling to get the body into the best position for the stroke.  When I hit a ball poorly, I can usually trace a lot of the problem to equally poor footwork.  Usually, it’s taking fewer steps, getting into position, then trying to ‘muscle’ the ball at impact.  A good stroke should be highly fluid, even if you don’t have to move very far to get to the ball.  When I’m hitting well, I’m taking lots and lots of very tiny steps as I position and then take the final step into impact.  In other words, I can always hear my feet moving when I’m hitting well.

The immediate question is how can you train to get better footwork?  I’ll answer that one on Monday.

Categories: Tennis Tags: , ,

Tennis Tip: Volley Out Not Down

July 29, 2009 Comments off

This tip comes from yesterday’s practice session.  I’m learning to play left-handed as I rehab a torn tendon in my right arm.  I was hitting with an instructor at the Hilton yesterday.  After an approach shot, he hit me a half lob to the backhand side.  I was able to get back far enough for a pretty decent swinging backhand volley, which was followed by an even deeper lob to the backhand side.  I was kind of excited after hitting the second one back, especially since the instructor set me up with a shoulder-high forehand volley for the next shot.  I had to stretch quite a bit to get there, but kept the racquet head above the grip, bent my knees, and watched the ball all the way into impact.

As soon as the ball impacted, I expected to hear the instructor say ‘great volley!’  Instead, I was greeted with the sound of the ball hitting the top of the net tape and watched it fall back on my side of the court.   I can’t blame the fact I was hitting left-handed.  I had let my arm drop a bit to ‘bring the volley down into the court.’  This is something I’ve even seen professionals do repeatedly.

Psychologically, there seems to be an impression that if the ball is well above the net that we have to ‘work’ to bring it back down or the volley will go long.  In reality, the ball only goes where the racquet head directs it.  If the racquet head is in the proper position and aimed at the desired location in court, that’s where the ball is going.  We don’t have to do anything else to keep the volley in-court and on target.

Did I remember that?  No.  Instead, I let the excitement of hitting back-to-back swinging backhand volleys get to me and missed the easier forehand volley.

When I practice volleys on the ball machine, I always start by trying to direct the volley outward enough to make sure it goes long.  Then, I adjust the impact angle so that the volleys go deep in the court in order to get the proper feel for good depth.  Volleying should be a position of dominance; one where you are in control of the point.  There is nothing more frustrating than being in a position to win the point and dumping the ball into the net.  Often, this is a result of trying to put too much ‘direction’ on the ball to bring it downward out of fear of hitting the volley long.

If you find yourself hitting makeable volleys into the net, then either the impact angle is bad or you may be trying to ‘force’ the ball downward going into impact.   When I warm up at the net, I always try to tell myself ‘volley out not down’ before the first volley.  If only I had kept that thought yesterday.  Hope this one helps you.

Categories: Tennis Tags: , ,

Tennis Tip: Height of Swing

July 27, 2009 Comments off

This is the first in a series of tips I’m directing towards 3.5 and lower players.  If you’re a 4.0+, you probably need less tips and more practice/refinement of what you already know 🙂  I hope players find these helpful as I have used them in my own game or to help others with their games in the past.

When I was an avid golfer, I was very fortunate to have been a member of Hank Haney’s Golf Ranch and got to see Hank give several lessons.  He had a great ability to simplify complex swing issues.  One comment that stuck with me was that the correct swing for each golfer had the right amount of ‘up-and-down’ and the right amount of ‘back-and-forth.’  A simple way of saying that most people get too flat or too vertical at various points in their swing.

I see the same in tennis, particularly with players trying to put a lot of topspin on the ball.  Instructors always say, ‘swing low to high.’  That really means the path of the racquet head should be from below the ball to even with the ball at impact to above the ball past impact.  It does not mean from the shoe laces to three feet above your head.  Yet, that’s what I see in a lot of swings.  If the player contacts the ball sufficiently underneath, then the ball travels high and might hit deep in the court and bounce quite high.  That happens about one out of ten shots.  Many shots go long or worse into the net as a result of too much rolling up the back of the ball.  The player thinks they are not getting enough lift and corrects by making the swing even more vertical.  This action only makes the problem worse.

In reality, the swing needs more breadth (around the body) and less height.  You can get really good spin by brushing up on the ball with a swing path that moves the racquet head upward into impact (with a slightly closed face).  More breadth in the swing should get you more depth and some more consistency.  At the 3.0 level, it’s rare for rallies to last more than four shots, so a bit more consistency and depth goes a long way to winning more points.

So, if you try to put a lot of spin on the ball and still hit a lot of shots into the net, think about just brushing up on the ball and round the swing out more around your body.   In other words, think about hitting through the ball not up on it.  If you are aiming over the net and end up in the net, chances are you are rolling up the back of the ball, not hitting through it.

Although I frequently use video analysis of my own swing, there is no substitute for a session with your local USTA professional instructor.  Good luck!

Categories: Tennis

Myla and Charlene

July 24, 2009 Comments off

Best wishes to Roger and Mirka on the birth of their twin girls, Myla and Charlene.  Do we have a new WTA dynasty in the making?

Categories: General, Tennis Tags: ,

Degrafa Plottable Catmull-Rom Spline

July 24, 2009 6 comments

Progress has been slow with regular work and dealing with family issues, but the Degrafa BasicSpline class now supports (interpolative) parametric splines as well as Cartesian.  The previous CatmullRom utility was used to ‘decorate’ BasicSpline to create a plottable Catmull-Rom spline that can be described in MXML.  A screenshot of the basic demo is shown below.

Degrafa Catmull-Rom Spline

Degrafa Catmull-Rom Spline

The Degrafa spline is plotted as a sequence of quad. Beziers in red.  The Catmull-Rom spline utility is used to plot the same spline point-to-point in blue.   As long as any (interpolative) spline utility implements the IPlottableSpline interface, it can be used to create a Degrafa-plottable spline.  The code for CatmullRomSpline is simply

public class CatmullRomSpline extends BasicSpline
{
 private var _mySpline:CatmullRom;
 private var _isClosed:Boolean;

 public function CatmullRomSpline( _myPoints:Array=null )
 {
 super(_myPoints);
 _mySpline = new CatmullRom();
 super.spline = _mySpline;
 _isClosed = false;
 }

 public function set closed(_closed:Boolean):void
 {
 if( _closed != _isClosed )
 {
 _isClosed = _closed;

 // remainder tbd - current utilty supports closure but not 'unclosing' the spline
 }
 }

 override public function getX(_t:Number):Number { return _mySpline.getX(_t); }
 override public function getY(_t:Number):Number { return _mySpline.getY(_t); }
 override public function getXPrime(_t:Number):Number { return _mySpline.getXPrime(_t); }
 override public function getYPrime(_t:Number):Number { return _mySpline.getYPrime(_t); }
}

I’ve got some more work to do on the internals of BasicSpline, but I hope this will make it easy to implement a wide variety of splines in Degrafa.  In particular, I hope it enables people who want to port splines from other languages, but do not wish to dig into the Degrafa internals to easily implement splines in Degrafa.  Or, perhaps, it will just get me committed to the mental asylum.  If only people knew I was already blogging from there 🙂

A note about the demo – there are a fixed number of points used in the point-to-point plot, so it can be a bit grainy for splines with really long arc length.  The Degrafa spline is drawn segment-by-segment.  Click the space bar to compare vs. the C-R utility plotted point-to-point.  I have not yet implemented the closure as I’m thinking about making it close and re-open.  Update SVN if you want to access the source.

View demo.

View source.

Categories: Degrafa, Flex Tags: , ,

Weird Interview Experiences

July 22, 2009 2 comments

From @CafeRico on Twitter, this was a hilarious read,

In over 25 years of professional experience, I can’t say I’ve even come close to hearing anything like this in an interview.  Perhaps the closest was a professor we once interviewed who claimed to have a linear programming algorithm ideally suited for vector and parallel supercomputers.  He was suspiciously evasive during most of my questions and at the end of his presentation, he leaned forward with a crazed look on his face, and said ‘So, do you know of any computers that are good at dot products?’  He then stuck his toungue out and started licking his chops like a rabid dog over a steak.

So, what’s your weirdest interview experience?

Categories: General Tags: ,

40 Years Ago Today

July 20, 2009 2 comments

Most young whippersnappers in the ‘new media’ business don’t even know what Apollo was and were not alive on this historic day in 1969.  I remember my parents taking us to the neighbor’s house because they had a larger TV  so we could watch the moon landing.  It was the space program that fueled my interest in math and science.  As a kid, I had this dream of working in the space program,  so what the heck am I doing writing Flash applications?  Oh yeah, it’s that whole paying the bills thing 🙂

At least the young whippersnappers have done a phenominal job of reliving the excitement of the times online with great sites like http://www.wechoosethemoon.org/ .  I can only hope that the spirit of adventure, innovation, and exploration continues and I get to see a Mars landing in my lifetime.

Categories: General Tags: ,