Method and an apparatus in electromyography

• US 5,318,039 A
• Filed: 11/06/1992
• Issued: 06/07/1994
• Est. Priority Date: 07/31/1989
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Biolin AB (AddLife AB)
• Inventors: Kadefors, Roland, Sandsjo, Leif, berg, Tommy
• Primary Examiner(s): Sykes, Angela D.
• Application Number:
  US07/973,228
• Time in Patent Office: 578 Days
• Field of Search: 128/696, 128/706, 128/731, 128/732, 128/733, 128/781-782, 128/774, 128/905
• US Class Current: 600/546
• CPC Class Codes: A61B 5/389 Electromyography [EMG]

Abstract

A method and apparatus for detecting muscular status in which electrodes are connected to the body muscles being investigated for producing analog myoelectric signals which are amplified in an amplifier and fed to an A/D converter connected to a signal processing unit. A signal device is connected to the signal processing unit. The analog signals from the electrodes are converted, after amplification, into binary signals which are frequency-analyzed in the signal processing unit by comparing the appearance and/or position of a frequency spectrum in relation to a predetermined initial position at commencement of the detection. Signals relating to the shift of the frequency spectrum in relation to its initial position are emitted by the signal device or stored in a storage device.

Claims

1. A method for detecting substantially continually, over a period of time, muscular status to determine muscular fatigue, said method comprising producing analog myoelectric signals in response to activity of a muscle under examination, amplifying said signals to produce amplified signals, converting the amplified signals into digital signals, in successive calculation periods, producing from said digital signals a signal which characterizes a frequency spectrum of each of said myoelectric signals during each calculation period, comparing the signals which characterize the frequency spectrums to a base signal representing the frequency spectrum on commencement of said period of time of detection, producing output signals based on said comparing to represent muscular status for detecting muscle fatigue based on shift of said frequency spectrums beyond a predetermined value, and transforming said output signals representing muscular status into a state perceivable by a human being.

2. The method of detecting muscular status as claimed in claim 1, comprising storing in a signal processing unit the digital signals relating to the frequency spectrum of the myoelectric signals and the frequency shift thereof.

3. The method of detecting muscular status as claimed in claim 1, comprising producing a signal when any shift of the frequency spectrum exceeds said predetermined value thereby to signal muscular fatigue.

4. The method of detecting muscular status as claimed in claim 1, wherein said output signals are transformed into the state perceivable to a human being at least one of an optical, acoustical and tactile signal.

5. The method of detecting muscular status as claimed in claim 4 comprising forming said output signals with one of amplitude and frequency related to a shift of the frequency spectrum.

6. An apparatus for substantially continually detecting muscular status to determine muscular fatigue comprising electrode means for producing analog myoelectric signals related to muscular activity of a muscle of a subject under examination, amplifier means for amplifying said signals, A/D converter means connected to said amplifier means for converting said analog signals into digital signals, signal processing means connected to said A/D converter means for receiving signals therefrom and forming intermediate signals related to the frequency spectrum of the myoelectric signals at periodic intervals, said signal processing means including means for detecting, at said periodic intervals, shift in the frequency of the frequency spectrum of said intermediate signals in relation to an initial frequency, in a calibration period when first receiving the myoelectric signals, means for emitting, during each said interval, at least one signal representing muscular status of the muscle under examination based on said shift of said frequency spectrum in relation to said initial frequency and for producing an output to indicate muscle fatigue if said shift of said frequency spectrum exceeds a predetermined value, storing means for storage of the signals representing the shift of the frequency spectrum, signal means for transforming said signals representing muscular status into information which is perceivable by a human being, and means for connecting at least one of said storing means and said signal means to said signal processing means.

7. The apparatus as claimed in claim 6 wherein said information from said signal means comprises a signal which is at least one of optical, acoustic, and tactile signals.

8. The apparatus as claimed in claim 6 wherein said signal means produces signals having a characteristic related to the shift of the frequency spectrum within a predetermined frequency range for the signals produced by the electrode means.

9. The apparatus as claimed in claim 8 wherein the characteristic of the signals produced by the signal means is at least one of amplitude and frequency.

10. The apparatus as claimed in claim 6 wherein said signal means includes means for converting electrical signals to acoustical signals.

11. The apparatus as claimed in claim 6 comprising control and communication means interconnected between said signal processing means and said signal means.

12. The apparatus as claimed in claim 11 wherein said control and communication means emits signals which are at least one of analog and digital.

13. The apparatus as claimed in claim 11 wherein said control and communication means supplies control signals to said signal means for adjusting at least one of the frequency and amplitude of the signals produced by said signal means.

14. The apparatus as claimed in claim 6 comprising control and communication means connected to said signal processing means and including said signal means.

15. The apparatus as claimed in claim 6 wherein said signal means produces signals having amplitude and frequency, at least one of which is changed when the frequency spectrum of the signals produced by the electrode means is shifted towards lower frequencies.

16. The apparatus as claimed in claim 6 wherein said signal processing means supplies control signals to said signal means for adjusting at least one of the frequency and amplitude of the signals produced by said signal means.

17. The apparatus as claimed in claim 6 wherein said storing means stores digital information relating to the frequency spectrum of the myoelectric signals produced by the electrode means, said storing means being separable from the apparatus.

18. The apparatus as claimed in claim 6, comprising means for establishing a threshold for said predetermined value of the shift of frequency spectrum from the frequency measured during the calibration period, said means for emitting, during each said interval, at least one signal representing shift of said frequency spectrum including means to send a signal to said signal means to produce an alarm signal when said threshold is exceeded.