Tennis Tip: A Great Use For Old Overgrips

This tip is a modification of a suggestion given to me by my instructor.  One afternoon, he tied an old overgrip onto the top of his racquet and took some practice swings.  The idea was to show that with a smooth swing (no pauses), the overgrip should not fall towards the ground.  Same thing with the serve; no pause at the top of the motion means the overgrip should not fall (due to gravity).

I’ve mentioned before that I’m learning to play left-handed while rehabbing my right shoulder.  I thought it would be fun to learn how to serve left-handed (kind of a Luke Jensen wannabe).  I was really having trouble getting a good ‘snapping’ motion going into the ball.   One of the items I had been working on right-handed was getting more wrist motion and arm break right after impact.  Look at photos of Sampras just after impact on his serve.  The wrist has moved so much through impact that the racquet is pointing downward and this motion is supported by the arm bending at the elbow.

Now, you can naturally achieve that kind of motion by cracking a bullwhip in the air, pointing it to some imaginary point beyond the serve’s anticipated impact point.  However, I don’t want to buy an Indiana Jones bullwhip and I’d rather do drills that involve an actual tennis racquet.

I was thinking back to Tom’s tip about the overgrip, so I tried it with the service motion.  I treated the racquet as the ‘handle’ of the bullwhip and the overgrip as the actual whip.  With that mental visualization, it was easy for me (even left-handed) to get a smooth, natural snapping motion through impact.  Just try to hit some imaginary point in the air with my modified ‘bullwhip rig.’

Once I start practicing right-handed again, I’m anxious to try this drill at home and see how it translates to racquet-head speed through impact.  Mental visualizations are always tricky; what works for one person may not work for another.  It does seem, however, that I’ve found a new use for old overgrips and I am a big fan of recycling.  Hope this one might have some benefit for you.

Good luck with the game!

Degrafa Closed-Loop Catmull-Rom Spline

Just a quick update that support for closed-loop C-R splines has been added to Degrafa.  The algorithmis is the same one as used in Singularity and is documented in this TechNote.  The algorithm is designed to provide G-1 continuity at the join and works best if the knot sequence approximately represents a closed shape.  If the outermost knots are ‘pointing away’ from each other, behavior is unpredictable.

The current implementation is targeted towards a use of defining a single knot set with closure and no further modification.  It is not possible to add knots to an already closed C-R spline.  It is not currently possible to re-open the spline after closure.  These constraints are based on discussion with designers  on most likely usage. They are subject to future modification if people come up with applications that require closure and then re-opening of the spline.

A screenshot of a simple example is shown below,


There is no need to manually duplicate the first knot – doing so would result in undesired consequences.  The MXML is simply

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx=""
 width="600" height="500"
 pageTitle="Closed Catmull-Rom Spline">

 <mx:Canvas id="background" x="50" y="90" width="500" height="320"
  backgroundColor="#FFFFFF" />

 <paint:SolidStroke id="bluestroke" weight="2" color="#0000FF"/>
 <mx:Canvas id="splineLayer" />
 <splines:CatmullRomSpline id="spline" graphicsTarget="{[splineLayer]}"
  knots="150,230 230,170 370,210 390,320 280,360 160,320"
  closed="true" />

Not much here and not really worth a demo. Update SVN to access the new source.

TennisTip: Train Like a Boxer For Better Footwork

In the previous tip, I alluded to ‘hearing’ your feet while practicing as a means to produce fewer steps and more adjujstment in setting up to hit the ball.  It’s very difficult to hit a good shot without the body being in proper position.  My biggest footwork issue is taking too few steps and getting in position early.  Instead of stepping into the ball as part of the stroke, I’m already setup, so I have to ‘muscle’ the ball with my upper body and arm.

In searching for a drill to help alleviate this tendency, I looked at other sports where the pace of action is fast and footwork is extremely important.  Martial arts in general, and boxing in particular fit the bill.  One of the old-school techniques for teaching balance and footwork in boxing is to tie a string between the boxer’s feet while standing in a ‘ready’ position.  Either through shadow-boxing or moving with a partner, the boxer must quickly move into a variety of positions without breaking the string.  This forces the boxer to make adjustments in small steps, allowing him to more quickly react to an opponent’s move in mid-step.  Not all that different from tennis; making adjustments for wind, ball spin, the ball hitting slick spots on the court, misreading a volley angle, etc.

So, I tried it … at home, of course.  Just hitting a foam ball up against a wall.  Freaking amazing drill.  What I thought was a small step broke the string instantly.  Then, I videotaped myself and saw what I was doing; trying to ‘position’ myself as quickly as possible, then hit through the ball as opposed to a single, fluid motion.  I comapred this to some video I recorded of Federer.  It’s interesting how many times his strokes have been analyzed and I never hear anyone talk about his feet.  His stroke production really begins there.

So, I continued with the drill until I could hit some really basic forehands and backhands without breaking the string.  I try to duplicate this motion when I warm up.  When doing so, I always tend to hit much better than when I warm up thiking only about stroke production in the upper body.

This is a drill that is not easy to migrate to the court, so I typically relegate it to indoor practice when it rains.  Breaking and retying a string is tedious, but don’t use a flexible cord as that could easily induce tripping.   In fact, I would recommend just practice moving into position without hitting a ball at first.   It’s a bit risky, but I found it to be an incredible drill that I can do at home.  If you don’t want to try it, at least have your local USTA pro analyze your footwork with you on video.  The bottom line is to consciously make an effort to keep the feet moving and constantly adjusting to the ball.  Always think of the stroke as starting from the ground; not the hips or the shoulders or the arm.  It’s the feet!

Good luck!