Quantitative Measurement of Muscle Fatigue by Electrical Impedance Myography

A portable device for measuring bioimpedance-related properties of skeletal muscle tissue, comprising:

• a plurality of electrodes, the plurality of electrodes configured to be simultaneously placed in contact with the tissue, the plurality of electrodes comprising:
• (a) a first set of electrodes arranged along a first axis, the first set of electrodes including (i) a first pair of current electrodes and a first pair of voltage electrodes positioned between the first pair of current electrodes, and (ii) a second pair of current electrodes and a second pair of voltage electrodes positioned between the second pair of current electrodes, and
• (b) a second set of electrodes spaced apart and arranged along a second axis non-collinear with the first axis, the second set of electrodes including (i) a third pair of current electrodes and a third pair of voltage electrodes positioned between the third pair of current electrodes,
• wherein each electrode of the first, second, and third pairs of current electrodes and voltage electrodes are spaced apart from the other electrodes of the first, second, and third pairs of current electrodes and voltage electrodes;
• and
• electronic circuitry configured to obtain (i) first data by directing current at multiple frequencies through the first pair of current electrodes and measuring the voltage across the first pair of voltage electrodes, and (ii) second data by directing current at multiple frequencies through the third pair of current electrodes and measuring the voltage across the third pair of voltage electrodes.

A method of measuring a characteristic of a user's skeletal muscle tissue, comprising:

• positioning a plurality of electrodes of a portable device in contact with a first location on or on the skin outside of the skeletal muscle tissue, wherein the plurality of electrodes includes a first pair of current electrodes and a corresponding first pair of voltage electrodes;
• obtaining data by directing a current into the first location of skeletal muscle tissue through the first pair of current electrodes and measuring a voltage across the corresponding first pair of voltage electrodes;
• and
• calculating at least one characteristic of the skeletal muscle tissue at the first location based on the obtained data.