referring to fig1 and 2 a strap - on training device 20 is shown . the device 20 includes a substantially flat central body or case 22 and a securing strap 24 configured much like a conventional wrist watch . the device 20 is shown in fig2 being worn on the wrist of an athlete 26 , and strapped to an upper arm region in fig6 as will be described below . the present training device is especially suited for teaching young or inexperienced baseball pitchers the proper throwing motion to reduce the chance of injury . although the description following will be kept within the baseball pitching environment , it will be appreciated by one of skill in the art of sports instruction that the present invention may also be applied in the training regimen of other athletes who practice similar violent overhead throwing motions . such other activities include , for example , tennis , racquetball , football , etc . now with reference to fig2 through 4 , a wrist - mounted version 28 of the training device 20 will be described . the wrist - mounted version 28 is designed to be strapped to the upper flat portion 29 of the wrist . fig3 shows the simple internal circuitry of the wrist - mounted version 28 within the central body or case 22 . a series circuit within the case 22 comprises a battery 30 , a mercury switch 32 , an on - off switch 34 and an alarm buzzer 36 . as seen in fig4 the mercury switch contains a small amount of mercury 38 within a cylindrical housing 39 . at one end of the housing , two electrical terminals 40 form a physical gap in the series circuit . the mercury switch 32 is oriented within the central case 22 so that a central axis 42 lies normal to the generally flat central case . as seen in fig4 with the device 28 held upright , the mercury 38 resides at the opposite end of the mercury switch from the terminals 40 and thus the circuit is open . a ray or vector 44 extending from the terminal 40 end of the housing 39 of the device 28 must be directed upward for the mercury 38 to remain at the opposite end of the housing from the terminals 40 so that the switch 32 stays open . as will be explained below with respect to fig5 a - 5d , a preferred method of pitching comprises wearing the wrist - mounted training device 28 such that the vector 44 is pointed upward during the backswing and entire power stroke of a throwing motion . an entire traditional throwing motion for baseball pitching includes a wind - up , bringing the hands behind the head with the body starting forward , a coiling or tucking motion with the forward leg raised , breaking of the hands with the throwing arm swinging behind the pitcher , a forward stride combined with an upward cocking motion of the throwing arm , and finally a forward power thrust of the arm terminating in release of the ball and full extension or pronation . the critical portion of the entire throwing motion occurs from the backswing of the throwing arm and continues through to release of the ball . during this portion is when the greatest stresses to the arm are generated , and thus highest threat of injury realized . fig5 a shows the arm during the backswing after breaking of the hands and prior to the initial forward and upward motion . fig5 b shows the arm coming up after the backswing . fig5 c shows arm at the start of a forward thrust of a throwing motion . and finally , fig5 d illustrates the arm during the forward thrust of a throwing motion approaching release of the ball . in all these arm positions , the wrist - mounted training device 28 remains oriented on the wrist 29 such that the vector 44 points upward and the buzzer 36 stays silent . any rotation of the wrist so that the fingers are under or on the side of the ball causes the alarm buzzer 36 to sound , alerting the pitcher to improper throwing technique . desirably , the fingers remain on top of the ball so that the vector 44 makes at least a 5 degree upward angle with a horizontal plane to ensure the buzzer 36 does not sound . more preferably , and to best prevent injury , the fingers must be more completely on top of the ball and the device 28 is tuned to close the switch 32 when the vector 44 makes an upward angle of 30 degrees or less with a horizontal plane . an alternative training device 48 of the present invention is shown in fig6 and 8 . this embodiment is designed to be worn on an upper arm region 50 of an athlete . the device is similar to that shown and described with reference to 3 and 4 with the orientation of a mercury switch 52 being modified . specifically , the mercury switch lies parallel to the generally flat central case 22 and generally perpendicular to the direction in which the securing strap 24 lies . a central axis 54 extends through the switch 52 and projects from one end as a vector 56 pointing out one side of the case 22 . when worn on the upper arm 58 in a resting position as seen in fig6 with the vector 56 pointing upward , the mercury 60 remains at the opposite end of the switch housing 62 from the terminal contacts 64 . now with reference to fig9 a - d , a sequence of snap - shots of a pitchers throwing motion , identical to the snap - shots of fig5 a - d , is shown . the alternative embodiment of the device , unlike the first embodiment , is designed to activate the buzzer during a crucial portion of the correct throwing motion . specifically , the correct pitching motion includes maintaining the elbow above the shoulder during the forward thrust phase . to illustrate the function of the alternative embodiment , fig9 a and 9b show the device with the vector 56 running from the elbow to the shoulder . in fig9 b , the vector 56 makes a slight downward angle with the horizontal so that the mercury switch 52 closes and the buzzer 36 sounds . desirably , the upper arm - mounted device 48 is tuned to activate the alarm buzzer when the vector 56 lies at or below the horizontal plane . more preferably , the mercury switch is fluid - damped to effectively delay closing of the alarm circuit until the vector 56 makes at least a five degree downward angle with the horizontal . thereafter , during the forward thrust phase , for proper technique , the device 48 is tilted so that the mercury 60 remains at the end of the housing 62 where the terminals 64 are located , and the switch stays closed . the buzzer 36 thus sounds during the entire forward thrust , as represented by the arm in fig9 b - 9d . the wrist - mounted training device 28 of fig3 and the upper arm - mounted device 48 of fig7 can be worn simultaneously to combine the beneficial aspects of their proper technique signalling modes . in a particularly useful arrangement , the devices incorporate different auditory signalling means , such as an alarm buzzer and a whistle , so as to better distinguish their outputs . in a multi - purpose configuration of fig1 and 11 , a combined wrist and upper arm training device 70 is shown . in this combined device 70 , there are two mercury switches : one switch 72 oriented in the same manner as the mercury switch 32 of the wrist - mounted device 28 of fig3 and the other switch 74 oriented identical to the switch 52 of the upper arm - mounted device 48 of fig7 . the device further includes a battery 76 , an alarm buzzer 78 , and two manually - activated switches 80a , 80b . the two switches 80 function as a single toggle switch , wherein depressing one selects one of the mercury switches 72 or 74 exclusive of the other , and visa versa . thus , this combined device 70 can be worn either on the wrist or on the upper arm depending on which aspect of the pitching technique needs the work . the pitcher need only toggle the switches 80 and move the device 70 along his or her arm to change from the wrist to the upper arm , or visa versa . of course , two of the devices described in fig1 and 11 can be worn at the same time to work on both the wrist and the upper arm technique , simultaneously . although the present invention has been described in terms of certain preferred embodiments , other embodiments are possible and the scope of the invention is to be defined by the following claims .
a training device for use by baseball players to help correct certain undesirable arm motion technique which might lead to catastrophic injury . the device utilizes one or more gravity - activated switches connected in a circuit within a case of a strap - on assembly . the gravity activated switches are oriented a specific way within the case , and the case strapped to a specific location of the arm so that certain undesirable arm motion will cause the gravity actuated switch to close and an alarm buzzer to sound . conversely , the switch may be oriented so that the buzzer only sounds if the correct technique is practiced . the device is particularly useful in a preferred training method for baseball pitchers .