This article deals with some of the basic Biomechanics involved with a Table Tennis Stroke.  It breaks down the stroke into three components. 
 
 
 
1.      Backswing
2.      Contact with ball
3.      Follow-through
 
 
The Role of the Backswing
Key elements for timing and power production.

the back-swing plays the primary role within all stroke techniques.  It sets the stage for power production as well as provides the key element in establishing the proper timing of the stroke.
Basic Biomechanical Principals Involved
1.       For efficient movement and power production, the large muscles involved must move before the smaller muscles.
·         To achieve this, the back-swing must start with the weight being transferred from the left to the right leg (right- handers).  This is accomplished by the right knee bending.  Next the hips rotate, then the upper body rotates, the arm then extends and finally the wrist flexes. 
·         During the forward swing into the ball, the order of movement of the muscles and joints is the same with the swing beginning with the weight transferring from the right to left leg. 
2.      Continuous Swing Concept – From the start of the back-swing to the completion of the stroke and the recovery to the ready position, there should be no break (stopping) in the stroke.
·         Newton’s First Law – A greater force is required to start a body in motion than is required to keep it moving.
·         Racket acceleration is the key element in putting energy into the ball.  It is much more difficult to accelerate a racket from a stopped position.
·         A continuous swing also helps in the timing of the stroke.  The athlete should take the racket back about the same speed as the on-coming ball.  The object is to always complete the back-swing at the moment the ball strikes the table.  This means that the speed of the back-swing will vary with the speed of the on-coming ball.
3.      The more joints involved in the stroke, the more acceleration that can be generated.
·         Strokes are whip-like motions; with the forearm snap the most important single movement.
·         The arm must be kept loose and relaxed during the complete swing. 
·         The biceps muscle controls the forearm snap during forehand strokes.
·         Muscles are like springs and store power.  For the biceps muscle to contract quickly, it needs to be extended (straighten) enough to cause tension on the tendons.
The Basic Elements Of All Strokes
How, when, and where to contact the ball, are the key elements in stroke production>

scientific study has shown that there are certain basic principles that must be executed properly for any stoke to be successful.  These basic elements cut across styles and grips and are the building blocks to truly understanding the correct stroking of the ball.  When a student understands how these elements work together, they quickly learn to make their own stroke corrections.
 
Basic Biomechanical Principals Involved
 

1. Application of Force and Friction
   “How to Touch the Ball”
   • Force Contact occurs when a foreword-moving racket strikes the ball.  An example of this occurs when you bounce the ball straight into the air on the racket.

                                                              i.      You can often hear a “wood” type of sound when producing Force Contact.
                                                            ii.      Most of the energy goes into producing forward motion.
 
 

• Friction Contact occurs when you brush the ball with the racket.

                                                              i.      Most of the energy goes into producing spin.
                                                            ii.      Most strokes are a blend of Force and Friction Contact
                                                          iii.      Slow Loops, serves, and pushes are maxim spin and minimum force.
                                                          iv.      Fast Loops are medium Force and medium Friction.
                                                            v.      Counters and Kill Shots are maximum Force and minimum Friction
·         Force has a direction:
 

·         Against Topspin                      --          Down and Forward
·         Against Backspin                    --          Up and Forward
·         Against Right Sidespin           --          To Your Left
·         Against Left Sidespin             --          To Your Right
·         Against High Ball                   --          Downward
·         Against Low Ball                    --          Upward

 

 

2. Timing – When the racket’s energy is transferred to the ball.
   • Ball is on the rise
   • Ball is at the top of the bounce
   • Ball is descending

 
 

Stroke + Timing

Rising

Top-Bounce

Descending

Counter drive

Yes

Yes

 

Fast Loop

 

Yes

 

Slow Loop

 

Yes

Yes

Reloop-off-bounce

Yes

 

 

Counter Loop Mid-distance

 

Yes

Yes

Normal Push

 

Yes

Yes

Fast Push

Yes

 

 

Chop – Mid-distance

 

Yes

Yes

Chop-Long-distance

 

 

Yes

Block against loop

Yes

 

 

 
 
 
 

3. Where to contact the ball.

 

• Most Important of the Three Principals
• Always Contact the Front of the Ball
• Front of the ball is an area, not a specific point.
• The Front of the ball is a constantly changing area, determined by the trajectory of the ball.
• It is the part of the ball facing the direction of travel.
• Area of Contact for Various Strokes

 

Counter against Topspin

Above the center of the front

Kill against Backspin

Center or below center of the front

Slow loop against Backspin

Below center of the front

Fast loop against Backspin

Center or below center of the front

Reloop from Mid-distance

Center or below center of the front

Reloop from Close-table

Top of the front

Push against Backspin

Center or below center of the front

Chop from Mid-distance

Above or center of the front

Chop from Long-distance

Center or below

 
 

• Front of the Ball

 

 
 
 
The Follow-through
The finish and recovery stage of a stroke

the final phase of the stroke is the FOLLOW-THROUGH.  Obviously, a correct follow-through results from a correct back-swing and proper contact with the ball.  Thus, the follow-through serves as a way to evaluate the stroke.  It also serves several other key functions in correct stroke production.
.
Basic Biomechanical Principals Involved
 
1.      The Follow-Through prevents a loss of linear velocity at the moment of impact or release.
·         The maximum speed of the racket should occur just as the ball leaves the racket.  At this moment, all body parts that were used must make their contribution to generate force (acceleration of the racket).
·         The follow-through prevents a decrease in this acceleration, before the ball leaves the racket.  This is accomplished by maintaining a steady contraction of the involved muscles until the motor act is completed.
2.      The Follow-Through prevents injuries that can be caused by an abrupt stopping of a moving body part.
·         Moving body parts possesses momentum.  An abrupt reduction of this momentum may cause injuries to both muscles and joints.  A proper follow-through allows for a gradual loss of this momentum.
3.      The follow-through provides the necessary time to perceive feedback information.
·         At the completion of the stroke, the follow-through provides a brief inactive period during which visual or kinesthetic feedback can be received and interpreted by the player.  The athlete’s body uses this information (conscious + unconscious) to make corrections in the strokes.
4.      The follow-through places the body in the proper "ready position" to begin the next motor activity.
·         The Athlete should return to the ready position at the conclusion of each stroke.  However, few players conceive this as part of the actual follow-through of the stroke.  Instead they stop their follow-through and then make a separate recovery move.  This will greatly slow down recovery time. 
1.      There should be no stopping of the racket from the beginning of the back-swing until recovery to the ready position.
2.       Having the Athlete think of each stroke as a complete unit will greatly increase their quickness around the table.