Electrical neuromuscular stimulator for measuring muscle responses to electrical stimulation pulses

#The invention concerns an electrical neuromuscular stimulator for measuring muscle reactions generated by electrical stimulation pulses. The stimulator includes an electrical pulse generator arranged in a case, at least one pair of stimulation electrodes intended to be placed on the skin of an user in the vicinity of the motor points of the muscles to be stimulated, each electrode being connected to one end of an electric cable, the other end of which is connected to the case to receive the electric pulses from the generator, at least one sensor sensitive to the muscle reactions caused by the electric stimulation pulses and arranged for transmitting electric measuring signals representative of said muscle reactions to electronic means in the stimulator case.

#The invention also concerns an electric cable and a stimulation electrode for a neuromuscular electric stimulator.

#The sensor supplies data regarding the useful muscle reactions in particular in order to know the fatigue level of the electrically stimulated muscles. The measurements obtained from the sensor allow the parameters of the electric stimulation pulses to be adjusted either manually by viewing the shape of the signals received by the sensor on a display or automatically by adjusting the electric stimulation parameters as a function of the muscle fatigue. Adjusting the parameters consists in correcting either the frequency of the pulses, or the amplitude or duration of the voltage or current pulses, or the duration of muscle contraction and relaxation, or the number of contraction/relaxation cycles, or any combination of the preceding parameters.

#The objects, advantages and features of the stimulator will appear more clearly, in a non limiting manner, in the following description of the different embodiments illustrated by the drawings, in which:

#FIGS. 1a and 1b show the stimulator before and after the connection of the electric cables to the electrodes placed on a user's skin,

#FIG. 2 shows a partial cross-section of a first embodiment of an electric cable connector with an integrated measuring sensor fixed onto a stimulation electrode,

#The stimulator described hereinafter relates preferably to a stimulator used within the field of sport and re-education in which muscle stimulation is used to exercise them passively. Rectangular current pulses are supplied to electrodes 7 placed on the skin at the motor points of the muscles to be stimulated. In response to this stimulation, the muscles contract generating a mechanical twitch. As previously described, current pulses have proved preferable to voltage pulses, since one is not dependent upon the variable impedance of the electrode and the skin of the person using the stimulator.

#Current pulses are supplied over time at a given frequency. According to the pulse repetition frequency, the muscles do not have time to relax before the next pulse which increases the working power of the muscles, but on the other hand, they become tired. It is thus advantageous to know the fatigue of the stimulated muscles in order to know the state of the muscles being exercised and also to be able to take advantage of this measurement in order to adjust the stimulation parameters automatically.

#In FIGS. 1a and 1b, the stimulator is represented by a case 1 enclosing in particular the current pulse generator and the means for receiving the signals originating from the sensor. On said case 1, programme selection buttons 2 are used to select the desired exercising mode as a function of the sport usually practised or the stimulation programme as a function of the pathological state (amyotrophy, hypotony, . . . ) of the muscle to be re-educated. The stimulator also includes a visual display device 3 for displaying in particular the programmes selected, the stimulation pulses, the muscle reaction measurement responses, or even statistics for the exercising sessions. Display 3 is formed for example by a liquid crystal display.