BIOFEEDBACK DEVICE FOR MONITORING MUSCULAR MOVEMENT

BIOFEEDBACK DEVICE FOR MONITORING MUSCULAR MOVEMENT

Field of the Invention

The present invention relates to sports equipment, and more particularly to biofeedbac devices used in developing sports skills.

Background of the Invention

A wide variety of devices have been developed in the past for use in teaching sports skills. In some instances, the devices have included mechanism for limiting body movement. For example, U.S. Patent No. 3,608,896 shows a device for restraining leg movement in teaching figure ice skating. In other instances, the devices have included strain gauges that determine the force exerted by a particular muscle. One such device is marketed by Integrated Sports Electronics, Inc. under the mark StrokeMaker.

There has been a long standing need for devices used to teach sporting skills wherein the device does not interfere with the body movement. Any interference, of course affects the body movement, and thus has limiting effects when used in teaching sporting skills. If a strain gauge is used in teaching tennis, the device itself may change the arm movement of the tennis player. Likewise, a muscular restraint in golf makes the swing unnatural and results in a different feel than is encountered when the device is not present. Such strain gauges are illustrated in U.S. Patent No. 4,501,148 (Nicholas et. al.). In this instance, the strain gauge is used primarily to measure muscle force. Another such device is illustrated in U.S. Patent No. 4,103,896 (LaRang) . This device provides a gripping mechanism on a golf club to signal excess force when gripping by the off target hand. In another instance, an accelorama curve is provided for measuring acceleration or velocity in the swing, for example, of a bat or golf club. This device is shown in U.S. Patent No. 3,717,857 (Evans). In each instance, the device adds significantly to the weight and feel of the bat or golf club, and thus produces an unnatural swing feel. The present invention provides a device free of such inherent disadvantages.

Summary of the Present Invention

The present invention provides a biofeedback mechanism which recognizes electrical impulses created by the nerves activating selected muscle groups. The sensing device may determine the timing of a muscle contraction by identifying when the electrical impulse is created. In other instances, the device may determine the magnitude of the electrical impulse and thus the magnitude of the muscle contraction.

The present invention includes mechanism for measuring electrical impulses created by activated nerves and mechanism for indicating the magnitude of the electrical impulse. The mechanism for measuring the electrical impulse may include a light weight band carrying a plurality of electrodes. The weight may be equivalent to a wrist watch. The band may be simply a light weight elastic cloth sized to snugly, but not restrietively, surround the muscle involved, for example, the muscles of the forearm or the calf muscle of the leg. The electrodes may be mounted on the inner surface of-the band, and may for example, be of metal foil or other conductive, low resistant material which may include polymers. In certain embodiments of the present invention, the band may include a radio transmitter. In other instances, the electrodes may be connected by a fine wire to a mechanism for measuring the magnitude of the electrical impulses, for example, a readout device such as a strip chart or a highly sensitive oscilloscope or computer. In those instances where a small radio transmitter is provided on the band, the readout device may include a radio receiver which reproduces the transmitted signal and feeds the signal to a strip chart recorder, oscilloscope or computer. The method of the present invention includes measuring the electrical impulse of one or more muscle groups during an athletic skill movement, then comparing the magnitude of the electrical impulse at various points through the athletic skill movement to determine the muscle activation in coordination with other muscle activation as described in detail hereinafter.

In the Drawings Figure I shows a golfer wearing a band of the present invention;

Figure II is a perspective view of the band of the present invention;

Figure III is a view of the inner surface of the band of the present invention;

Figures IV through VI are views of an alternate embodiment of the present invention;

Figure VII is a graph showing the magnitude of electrical impulse from the trailing forearm of a golfer;

Figure VIII is a graph similar to Figure VII but illustrative of a golfer using an improper muscle movement on a trailing forearm;

Figure IX is a strip chart showing the cooperation of the readouts of a pair of measurements during a golf swing, specifically a trailing forearm and a leading calf muscle measurement;

Figure X is a strip chart graph showing a pair of corresponding measurements during a golf swing, specifically a trailing forearm and a leading calf muscle measurement; and

Figure XI is a strip chart graph showing a pair of corresponding measurements during a golf swing, specifically the muscle activity of the right forearm and the right calf during the golf swing. Detailed Description of the Invention

A golfer 1 is illustrated in Figure I using the arm band 10 of.the present invention. The band 10 may be an elastic strip of fabric forming a band which is held by friction around the forearm of a golfer at a point just below the elbow. Mounted on the inside of the band are two electrodes 11 and 12 and a ground 15 as illustrated in Figure III. Mounted within the band are a battery operated electronic amplifier 13 and a visual/audible indicator 14. The band may have a replaceable battery 16 and an on/off compressible switch 17. In lieu of battery 16, a solar cell or cells may be used. The band 10 may include adjustable securing mechanism such as a Velcro™ piece 18. Muscle activity in the human body is initiated by electrical nerve impulses from the brain. These impulses may be measured at the surface of the skin by the voltage differential between electrodes 11 and 12. The magnitude of the electrical activity varies proportionally with the force the muscles are commanded to exert. Thus, when the differential signal from electrodes 11 and 12 is measured, the measurement indicates the force of the gripping action of the fingers of the hand. Preferably, the electrodes 11 and 12 are spaced, for example, 1 inch to 3 inches, and are aligned with the length of the forearm. The electrical voltage developed by the nerves is of course very weak. Therefore, a high gain electronic amplifier is used to magnify the amplitude of the electrical muscle signals. Desirably, a differential amplifier 13 which measures only the difference in voltage between the two electrodes is used, thus eliminating interfering electrical fields such as from power lines, static charges and the like. The amplified electrical signal may be of several volts.

The amplified signal is fed to an indicator device 14. The device 14 may be any suitable visual or audible device, analog meter, light emitting diode, or liquid crystal display. The device can be a bar graph liquid crystal display. Switch mechanism may be used to switch between visual and audible devices. The length of the darkened bar may be proportional to the force exerted by the fingers in gripping the golf club.

The device 14 may further or alternatively include an audible indicator which varies in pitch or maintains a constant tone. Thus, the tighter the grip, the higher the pitch or louder the tone. Alternatively, the audible indicator may have an intermittent tone with the rate of sound pulses indicating the force of the grip on the golf club.

The electrodes 11 and 12 are desirably made of silver or a silver plated disc. Alternatively, nickel, tin, or stainless steel electrodes may be used. The electrodes desirably provide high conductivity and low resistance, and yet resist corrosion from perspiration and body chemicals. Any suitable amplifier may be used. For example, the circuit illustrated in U.S. Patent No. 4,170,225 (Criglar et al) is suitable. The amplifier may include mechanism for immediately reporting the signal. Alternatively, electronic design may include mechanism for storing the visual signal, thus permitting the golfer to swing, then activate the playback mechanism and observe the visual signal.

The storing device may be a video recorder, e.g., VCR. The VCR may record both the actual swing of the golf club and the graph showing the force exerted. In various sports, the coordination of two or more muscle groups result in proper execution of the sports skill. For example, in a golf swing, the hand of the lead arm (e.g., left arm for right handed golfer) grips the club snugly, with force being applied by the forearm muscles of the leading arm acting on the fingers of the left hand. The forearm of the trailing arm desirably is relaxed through much of the swing; however, with three instances of muscle activation. The first activation is when the arms start the movement of the club rearwardly. The second activation is when the arms terminate the upward movement of the club. The third activation is when the arms tense as the club head strikes the ball. Between each of such points of activation, the forearm should be in a relaxed condition. If the relaxed condition is not achieved, the golfer will lose control of the direction of the ball (e.g., resulting in a slice) and the distance the ball travels will be reduced. Thus, the stored visuals of the right forearm will illustrate three levels if a swing is properly executed. If the levels or peaks are not observed, but rather a flat signal or sine wave is obtained, the golfer is notified that the muscle movement is improper and correction is explained.

Charts illustrated in Figures VII and VIII show results of a properly executed golf swing and a poorly executed golf swing, respectively. The properly executed golf swing is showed in Figure VII. Point A identifies a slightly increased grip during address and when the golf club is taken away from the golf ball and moves in an upward arc. Point B shows the muscle activity at the upper end of the golf swing, and Point C illustrates the return of the golf club to the ball (e.g., impact) .

The period of relaxation is of significance between Points B and C as illustrated by the downward slope of the line. Figure VII illustrates proper trailing forearm activity during a swing. Point A is the graphed peak when the club is initially held and moved rearwardly (take-away) . A valley is present following peak B showing relaxation of the trailing forearm until the ball is struck. A second peak C occurs when the club strikes the ball (impact) . A similar review of Figure VIII shows an improperly executed golf swing in which little relaxation occurs between Points Bl and Cl. Also, the impact peak Cl does not show a greater force than the force applied at the top of the swing (Bl) which will decrease potential distance achieved.

Measurements of other muscle activity may be made during a sports skill movement, e.g., calf of left leg in golf swing, forearm of racket arm for tennis and the like^".

Alternate Embodiment

An alternate embodiment 110 of the present invention is illustrated in Figures IV through VI. Training device 110 includes an elastic band similar to band 10; e.g., however, it further includes a small radio transmitter. The device 110 has a pair of electrodes

111 and 112 which are connected to an amplified radio transmitter 121. The radio transmitter 121 may be powered and controlled in a manner very similar to the display 14 of device 10. In other words, the radio transmitter 121 may be powered by a battery 116 and activated and deactivated by switch 117. The radio signal emitted by device 121 may increase in frequency as the voltage differential between electrode 111 and

112 increases.

A suitable receiver is provided in conjunction with a remote readout device such as a computer or strip chart 126. The strip chart 126 prints a chart of the muscle activity during a sporting skill movement (e.g., a golf swing) . The printed chart has several advantages. For example, it permits the accumulation of several golf swings, thus permitting comparison between different golfers or sequential swings of the same golfer.

The strip chart recorder 126 includes a radio receiver which amplifies the signal and converts the signal into needle movement or activate a print head, thus graphing the chart. Alternatively, the radio receiver may drive an oscilloscope or computer and may electronically store the signal for later review and comparison. This embodiment may also include another band to measure the activity of a second muscle group. This may be the activity of the lead leg calf. Since readings are taken simultaneously, the activity of the leg muscles .can be studied in association with the location of the golf club in the back swing, top of swing, forward swing, impact, and follow-through.

While preferred embodiments have been illustrated in the Figures I through XI, various other modifications may be made without departing from the broader scope of the present invention. For example, in the case of golf, the signal may be carried by way of small electrical wires which extend upwardly along the upper arms and legs of the golfer 1 and then to the rear where they are connected to amplifiers and then the signal is sent to a strip chart device or computer similar to device 126.

The Method of the Present Invention

While the method of the present invention may be apparent from the descriptions of Figures I through XI, it will be further described hereinafter.

The method of the present invention includes a first step of measuring the electrical impulse emitted by the nerves activating the particular muscle or muscles involved.. Next, the electrical signal is amplified and the amplified signal is used to communicate, for example, visually or audibly. The electrical signal at the surface of the arm, for example, may have a voltage of a few hundred microvolts. The amplification will typically increase the voltage to about 4 volts peak to peak. The letter range of voltage will be used to drive the liquid crystal device or other mechanism for display (e.g., the radio transmitter).

The preferred embodiment of the present method, a plurality of voltage measurements, are taken at various locations on the body. For example, the band 110A (Figure IV) may be placed on the right forearm of a right handed golfer HOB may be placed on the left forearm. Another band 210 may be placed on the left calf muscle, and a fourth band 310 may be mounted on the right calf muscle. Each of the bands 110A, HOB, 210 and 310 drive a separate needle on a strip chart or print head. For example, through radio transmitters operating at different frequencies, this provides for the creation of a strip chart which illustrates coordination of these muscle groups in a timed or coordinated pattern. By identifying the point or benchmark at which the ball is struck (e.g.. Point C in Figure IX), one can locate the shifting of the weight from the left foot to the right foot and back again to the left foot during a golf swing. Figure IX illustrates proper coordination of muscle activity of the right forearm and the left calf of the leg. As the graph shows, the body weight is shifted to the left calf and foot as the club approaches the top of the swing. The muscle tension of the left calf remains high until the point of impact and then there is gradual decay in tension during the follow-through.

Figure X illustrates improper muscle activity in the left leg. When the club is swung, weight shifts back and forth between the left and right legs. Figure XI illustrates proper coordination of muscle activity of the right forearm and the right calf during the golf swing. The tension of the right calf increases rapidly at the time of reaching the top of the swing. Then the tension rapidly falls off during follow through.

While the arms and legs of the golfer have been used as the vehicle for describing the present invention, it is to be recognized that the apparatus and the method are equally applicable to various other muscle groups of the golfer and muscles used in other sports. The muscle groups may be leg, back or shoulder muscles. Other sports, for example, would include tennis, racket ball, shot put and the like.

While specific embodiments of the invention have been described, it is to be recognized that various modifications may be made without departing from the broader scope of the present invention.