Prof.Ken's
   Rhythmic Serve_PRO

       Kenichi YUMINO([PhD] Emeritus Professor of Shizuoka Univ., Japan)

  <Development Policy of Rhythmic Serve_Pro Application>

   1. This application promotes gRhythmic Tennis Serveh

      An expert player hits a ball rhythmically in cooperating with hands, feet and a body. There is a stable fixed rhythm in execution of serve. Through this rhythmic hitting process, the expert player converge all balls near aiming point. On the contrary, a novice player hits ball awkwardly, and hardly has rhythm. It because that a toss rises too high or low, sometimes falls in improper location. In these reasons, novice player cannot make a stable rhythm. As a result, the serves are scattered wide on the court.

    This application was developed for aiming at advanced/high level player to get information(good rhythem or not) about serving process to hear Reaction Time( from own said "go" to "hit") in 1/100 second order. The novice and beginer, of course, can use this application.

  2. Tennis Serve has five movements

 The form and style of a serve is differed among players. However, the following five movemens are included in when we observe it in detail. Let's take an orthodox right-handed player as an example.

[1] Bring a racket and a ball close in front of body, and hold them.

[2] Not move largely the left hand that holds a ball, but move the right hand with racket near to the body.

[3] Toss a ball which holds in the left hand.

[4] Arching the body@backward, and making a large angle between arm and body, set the head of racket with right hand almost reach to the back.

[5] Being co-operate with arching the body, raise the racket fully, and hit the ball strongly with the snap that has a twist work.

  3. This application can measure an exact Reaction Time in 1/100 sec. order, and tells it the player.

    This application measures reaction time in the precision of 1/100 second order from "Go" to "Hit". By comparing a reaction time with the succeeded ones, the player can reflect the adequacy of a toss and a series of movement every trial.   

  <Usage of Rhythmic Serve_PRO Application>

   1. Stop WiFi and all applications you run

   2. Top screen has 3 buttons

  [1]USAGE:   Please read gUsageh first!
   [2]SETTING: On this screen, Number of Trials, Waiting time for next Trial( Interval Time) can set.
   [3]FINISH: Close this application.

   3. Begin every trial by shouting "Go"

   After pushed Start/Restart button, the buzzar sounds ,and about a half second later `poo sound" continues. On this timing, the player shouts "Go", and begins serve.

   4. Setting Screen

    [1] Number of Trials:  The number of serve trials you do.
    [2] Interval: Waiting time from gHith to the
start of next trial.
    [3] Get Balls/ x-Trials:  Every x-Trial,    there is a voice gget ballsh, after finished x-Trials. Please prepare next set of balls. And push Restart button.

   5.@Measuring Reaction Time Screen

       1) Reaction Time
     On this application, it can be measured Reaction Time (1/100 second order) from "Go" that is shouted by the player to gHith that is a hitting sound of a racket. In the serve exercises that aimed at a target place, it can be increase success probability of serves, by stabilizing the reaction times.

    2jMeasuring Reaction Time
     When a measurement of a reaction time begins, "Ongoing trial number / [All trial numbers]",gReaction timeh are shown on screen in orange color.@And upper three digits of the reaction time (1/100 sec. order) are pronounced.

@@3) After prepared new balls, push "Restart Button". New trial will begin.

    4)   After finished all trials, all reaction times, a mean and a standard deviation [SD] of it are printed on a new screen. . With progress of serve skills, the SD becomes small. If the number of trials becomes large enough, approximately 60% of all reaction times fall in the range of the mean } a SD. The SD is a sharp indicator of stability of serve skills.

6. Save and Transfer of Reaction Time Data

@@Reaction Time data are saved in "Document folder" of Inner Storage. "RhyMail_Pro" application has a gmail function. Please enter your "Google Account", and on the "Login and Seculty Page", change your permission.

     <The Key Points of the Rhythmic Serve_PRO>

The form and the way of the tennis serve vary among people. A series of movements and a rhythm from setting up to hitting are peculiar to the player.However, even if the movements and rhythm is differed among players, the following 6 movements are needed to make consideration for realizing stable serves.  Let's explain in case of a right-handed player for an example.

  ‚PD  In order to make a serve succeed, it is necessary to pay attention to six movements

   1)Movement @first:  Holding types of a tossing ball
    There are a few styles how to hold and toss a ball. A) Put a ball on the palm. B)  Grasp a ball with five fingers lightly. C) Put a ball on middle finger and surround it with a thumb and a forefinger and toss it like lifting up a cup. C) method is recommended for the beginner. (See Figure 1).


  Figure 1.  Holding a ball.

       But, as for the method of C), it is necessary to practice tosses much times. The reason is that the method restricts to use a wrist and a finger sufficiently. The movement is similar to a lifting up a glass to the high position. The novices liable to begin a toss with bend the knee and lower a ball near knee. However, this way of toss cannot stabilize serve because it is difficult to control height and the position of the toss exactly.

    2)Movement@second:  It is a state of ready to begin serving( it represented by a word "Ready").       The foot opens slightly, and a racket and a ball touched in front of a chest lightly. The important things are gravity of the body is put on the center, and the tension of whole body including shoulder falls out moderately, and the mind is relaxed. (See figure 2).


  Figure 2.  Movement of gReadyh.

3)Movement third:   This is movements that transforming the gravity to right foot not moving the ball so much that is holding in left hand , and bringing down the racket near to right foot (it represented by a word "One"). In the movement, that includes grasping a grip strongly just before a racket stops and relaxing it suddenly, may available for using left and right hand differentiate. For the beginners, it is recommended to turn a wrist up (See Orange circle in Figure 3) and stay racket face horizontally without greatly moving the head of the racket down. Because, the racket face made here becomes a suitable face when the ball is hitting at overhead position. Not moving the left hand so much, moving the right hand and making tense and relax in repeated practices may lead to control the hand of right and left separately. In other words, some rhythm that is necessary for carrying out accurate serve must be obtained.


  Figure 3.  Movement gOneh.

4)Movement fourth:   Movement fourth starts a toss with the left hand (it represented by a word "Two"). (See figure  4). The important point here is a keeping the racket of the right hand, influencing by the movement of the toss of the left hand.  When a toss and a racket moves simultaneously, trailed by the movement of racket, the toss flows backward, and hitting point locates behind the head, it is unable to hit strong serve.
      It is important to start the upswing of the racket, delaying a little from the start of the toss. Whether a toss is good or not can judge in the fallen position of the ball. When the ball is caught at tossed position, the toss is succeeded.


  Figure 4. Movement gTwoh.

5)Movement@fifth:  Movement fifth is to raise a racket quickly while bending both feet, to carry it over shoulder, to reach almost it to the back (it represented by a word "Three g). Middle and advanced players should link the movement of the racket and arching the body. On the contrary, the novices are recommended to use arching after the serve skills improved to some extent. Making delay a little from tossing, not reducing angle of the wrist (see Figure 3), and a player should carry a racket over shoulder and reach to the back quickly. This kind of form enables a fast and strong serve (See Figure 5).


  Figure 5.  Movement gThreeh.

6)Movement 6:   A movement of hitting a tossed ball (represented by a word "Hit"). (See Figure 6).
       In case of hitting ball, strech an arm up without loosing a wrist angle, synchronizing it with the leaning back of the body, and hit a falling ball strongly with twisting of the arm.@A little upward face hits the ball. As beginnerfs head speed of the racket is slow, accordingly the agle becoms large.
      In order to make a fast serve, it is effective that the practices of standing a racket quickly and throwing down it sharply, without using a ball. For the player who want to achieve a high speed serve , it is recommended to hit a ball at a little up position on the racket. This way enables to hit a faster serve.


  Figure 6. Movement gHith.

  <Make a rhythm and join five movements together>

  In order to acquire a precise and stable serve, it is recommended to connect six movements with a rhythm, after each movement become some extent stable throughout repeated practices of each movement.