a device 1 for preventing rsi by avoiding overload of muscles comprises means 2 for measuring a load on the muscles , means 3 connected to load measuring means 2 for comparing the measured load with a determined first threshold value , and means 4 connected to comparing means 3 for generating a warning signal when the measured load exceeds the first threshold value . the function of signal generating means 4 does not otherwise have to be limited to generating a warning signal in the case of too high a muscle load , but these means can also be adapted to generate a release signal when the muscle load once again drops below the threshold value . load measuring means 2 can herein directly measure the load exerted by the muscles , but it is also possible for these measuring means to measure the load indirectly by detecting a movement of a part of the body resulting from the load on the relevant muscles . in the first case the load measuring means 2 can comprise one or more sensors which are connected to a tool 6 which is operated by the muscles . as sensor 5 can be used for instance a pressure sensor with which a pressure force or grasping force of the muscles can be measured . the use of a strain sensor to measure a tensile force can however also be envisaged . sensor 5 can be arranged in a computer 7 ( fig4 , 5 and 6 ) or in a mouse mat 8 ( fig8 .). as stated , sensor 5 is connected to comparing means 3 , which can for instance take the form of a suitably programmed electronic circuit . this electronic circuit can be embodied as integrated circuit in the form of microchip 9 ( fig2 ). on this chip 9 can also be accommodated the signal generating means 4 which can likewise be formed by a programmed electronic circuit . sensor 5 and microchip 9 are herein connected to a power supply 20 , for instance a battery . the signal generating means 4 can further comprise a light source 10 and / or a sound source 11 . light source 10 can herein be a led , which is relatively small and requires little energy . the principle of the method according to the invention can be seen in fig2 . at points in time t 1 , t 2 and t 3 the sensor 5 is pressed in . as soon as the force exerted by the muscles on sensor 5 is greater than the threshold value f 1 , a clock is started internally in microchip 8 . if the load falls below the threshold value again within a predetermined time t , nothing will happen , as can be seen at the points in time t 1 and t 2 . if the force exerted on sensor 5 remains greater than the threshold value f 1 for longer than the time t , a warning signal will be generated after this time has elapsed for as long as threshold value f 1 remains exceeded . for an optimal result the threshold value of the force f 1 and the delay time t can be adjusted independently of each other . when the load measuring means are accommodated in a mouse 7 or mouse mat 8 , the rest of the device can also be accommodated therein , although it is also possible to include the comparing means 3 and signal generating means 4 in the form of an application program in a computer 12 connected to mouse 7 . computer 12 can therefore be programmed here to log the number of touches on a keyboard 14 connected to the computer , which may also form an indication of imminent rsi symptoms . in the case computer 12 is used , the signals generated by signal generating means 4 can take form of an animation . a cartoon character 13 can for instance be shown herein , the facial expression or even the general state of which forms an indication for the presence or absence of muscle tensions which involve the risk of rsi . computer 12 can herein be programmed such that the facial expression or state of the fig1 changes gradually as the measured muscle tension increases or decreases . the computer can further be programmed such that the fig1 gives information on the basis of which the user can adjust the load on his muscles , for instance by changing working posture or by temporarily interrupting his activity . in order to encourage users to adopt a good working posture and good working habits , computer 12 can be programmed to keep a score , which incorporates the frequency of ( imminent ) overload of the muscles . this score can be displayed on the relevant computer , wherein the user can then try to improve his score , while it is also possible to mutually connect a number of computers 12 in a network , which opens up the possibility of an “ rsi - competition ”. in addition to the computer mouse , writing instruments are also a source of rsi symptoms . in an alternative embodiment of the invention the sensors 5 are therefore mounted on a writing instrument 15 ( fig8 ). each sensor can herein be integrated with a comparing circuit and signal generating circuit in very small form to form a warning unit 16 . this warning unit 16 can also be releasably connected to writing instrument 15 . in that case the unit for instance takes the form of a single sleeve 17 ( fig9 ) or dual sleeve 18 ( fig1 ) which can be pushed or clamped round writing instrument 15 . in the case of the dual sleeve the comparing means 3 and signal generating means 4 are then accommodated in the rear compartment and load measuring means 2 in the front one . warning unit 16 could also take a self - adhesive form and for instance be wrapped round the writing instrument . the different components of device 1 could also be received in the body 19 of writing instrument 15 . a par 21 of writing instrument 15 can herein be of conventional structure , while device 1 is accommodated in the remaining part 22 ( fig1 , 13 ). in the ballpoint pen 40 shown in fig2 a part of housing 41 is provided with a pressure sensor 5 . pressure sensor 5 is connected via two wires 49 to a circuit 44 . circuit 44 is powered by batteries 47 and a led 45 is connected to circuit 44 . the ballpoint pen 40 is further provided with an ink cartridge 42 . because the present embodiment of the invention prevents the use of a clicking mechanism , the ballpoint pen can be closed by a cap 43 . further arranged is a transparent element 46 , in a recess of which the led 45 is placed . the space for the batteries is closed off by a cover 48 . instead of a direct measurement of the load on the muscles , the movement of a part of the body connected to the muscles can , as stated , also be detected . it is possible for instance to choose the shoulder 23 for this purpose , which is pulled up when there is too great a strain on the arm muscles , wherein particular nerve paths 24 and / or blood vessels 25 are irritated or pinched by the first rib 26 and the collar bone 27 ( fig3 ). the movement of shoulder 23 can be detected by an adjustable bracket 28 which rests on the shoulder , is adjustable in height and width and which can be mounted on the back 29 of a seat ( fig1 ). a movement of the shoulder can herein result in a displacement of bracket 28 , which can be detected by a movement sensor ( not shown here ). it is also possible to derive the movement of shoulder 23 from a force which is exerted by the shoulder on an article of clothing 30 . for this purpose a pressure sensor 5 can be arranged in this article of clothing 30 , for instance a bra . the detected movement of the shoulder is again compared with a threshold value by comparing means and results in a warning signal being generated when this value is exceeded . instead of the movement of shoulder 23 the pressure exerted by the body of a user on different parts of a seat 31 could also be taken as a measure for the muscle tension and the risk of rsi . pressure sensors 5 can be received for this purpose in a separate cushion 32 which is fixed on seat 31 ( fig1 , 17 ), or in the actual seatpart 33 , seat back 34 and / or arm rests 35 of seat 31 itself ( fig1 , 16 ). the invention thus makes it possible with relatively simple means to provide a warning when , as a result of for instance an incorrect working position or too great a number of repetitive actions , the danger of rsi is created , so that timely corrective measures can be taken . referring now to fig2 , a method for performing a therapeutic or prophylactic therapy on a patient suffering from or at risk of hypertension of the scalenius muscles may be performed over a website . a presently available commercial website offering such methods is www . norsiweb . com , owned and operated by an assignee of the present patent application , which first became accessible to the public on oct . 12 , 2001 , and is accessible on the filing date hereof . the methods described and claimed herein , however , are not meant to be limited to the operation of this particular website , and instead may be applied to other websites incorporating the described features as well as other forms of electronic communication , including video streaming , video conferencing , intranets , and the like . in order to facilitate the description , however , the following will be directed specifically at access of a website over the intranet or world wide web . a patient first accesses the website in a conventional manner using a computer , workstation , or other intranet access device remote from the server which maintains the programming which runs the website . after the website has been accessed , the patient will be directed to a web page which will initially collect data on the patient and the patient &# 39 ; s condition . an exemplary web page containing a questionnaire for obtaining patient data is shown in fig2 a and 28b . this web page is taken directly from the commercial www . norsiweb . com website as it existed at the time of filing the present application . the information included on this web page is , of course , only exemplary of information which might be obtained and which could be used to determine exercises for a course of therapeutic or prophylactic treatment . usually , this information need be obtained only once at the outset of a course of treatment , but optionally may be updated from time - to - time . once the patient data are collected , particular exercise protocols are provided to the patient over the internet , typically at the website but optionally via e - mail by other electronic communications . a number of exemplary exercise protocols are set forth in fig2 – 38 , respectively . these exercise protocols are taken directly from the commercial www . norsiweb . com as it existed on the filing date of this application . it will be appreciated that these exercise protocols are only exemplary and are intended specifically for use with the exercise pen described in detail earlier in this patent application . the exercise protocols may be performed singly or multiply in series , with individual protocols usually performed on successive days or alternatively with two or more different protocols performed on the same day . periodically , and typically after each exercise protocol is completed , the patient will be asked to complete a result summary , such as that shown in fig3 which is taken from the commercial www . norsiweb . com website as it existed on the filing date of the present application . the information gathered in this report allows program on the server ( or optionally personnel with access to the server - maintained information ) to keep track of the patient &# 39 ; s progress , including preparing summary reports of such progress . the data also allow additional exercise protocol ( s ) to be selected for the patient in order to further achieve the desired therapeutic or prophylactic goal . although the invention is described and shown above on the basis of a number of embodiments , it is not limited thereto . many variations are possible both in the embodiment and placing of the load measuring means and in the manner in which the measured quantities are processed and signaled . the scope of the invention is defined solely by the appended claims . influence of a writing with a sensor pen on the blood flow velocity in the artery subclavia . blood flow velocity in the artery subclavia is proportional to its diameter , which is determined by the available space in the costoclavicular gate . blood flow velocity in the artery subclavia is thus an indirect indication of the tension in the scalenius muscles , which determine the space in the costoclavicular gate . blood flow velocity in the artery subclavia was measured directly under the collarbone using ultrasound doppler measurements . blood flow velocities were measured in 9 persons ( a - i ) while resting before a writing exercise , while writing for 1 minute with a regular ballpoint pen , while writing for 1 minute with a norsi sensor pen , and in 3 persons ( f - h ) while resting after the writing exercise . blood flow measurements are shown in fig2 . writing with a regular ballpoint pen caused significant narrowing of the costoclavicular gate in all 9 persons compared to the situation in rest . in contrast , a 1 minute writing exercise with the norsi sensor pen releases the tension in the scalenius muscles , thereby widening the costoclavicular gate and restoring the diameter of the artery subclavia to values close to or even wider than those while resting . performing a writing exercise with the norsi sensor pen at least 4 times per day is sufficient to release hypertension in the scalenius muscles and widen the costoclavicular gate , thereby relieving the negative consequences of a narrowed costoclavicular gate . the norsi sensor pen used in this exercise has a pinch - grip force pressure sensor set at a threshold value of 150 – 175 grams , and generates three different light signals for biofeedback control during the writing exercise . a first short light flash is generated when the threshold value is exceeded for a short time . a second low frequency flash signal ( 4 times ) is generated when the threshold value is exceeded for more than 2 . 5 seconds . a third high frequency flashing signal is generated when the threshold value is exceeded for more than 10 seconds . influence of writing with a sensor pen on the gain in rotation of the cervical range of motion . 200 persons with complaints in the neck , shoulder and / or arms ( neck hernia , discopathy , arthrose / whiplash and / or frozen shoulder ) were asked to perform a writing exercise with the norsi sensor pen as described in example 1 . the cervical range of motion ( crom ) was determined immediately before and after the writing exercise . the differences in rotation angle of the crom in degrees before and after writing are shown in fig2 . clearly persons with complaints in the neck , shoulder and / or arms gain at least 15 degrees in rotation angle of the crom . the average gain in rotation angle of the crom was 25 , 3 degrees in this population . in this experiment the limit of motion as a result of muscular resistance was measured , as opposed to the limit of motion as a result of arthrogenic resistance ( see also fig2 ). the gain in rotation of the crom observed is therefore directly related to a release of tension in the scalenius muscles .