Development of Fine-Wire Intra-Muscular EMG Recording to Quantify Upper-Limb Fatigue in 'Tennis Elbow'

Objectives: muscle imbalance has not been scientifically studied yet as possible aetiology of tennis elbow and other similar musculoskeletal conditions. this study describes the development of a reliable clinical tool for objectively measuring fatigue contributions of the shoulder, and forearm musculature using fine wire emg. emg can be used to measure muscle fatigue and muscle imbalance. fine wire emg is more problematical to use than surface skin electrodes but their potential resolving power particularly regarding deep muscles was thought to be worthwhile pursuing. materials and methods: a purpose-built amplifier was designed and constructed (to the appropriate electrical safety standard, iso 60601) with extremely high input impedance and noise rejection properties specific to the fine-wire electrode situation. simultaneous surface and fine wire emg recording from supraspinatus using purpose built amplifier in order to compare the quality of signals acquired. surface electrodes were placed over the skin and fine-wire intra-muscular electrodes inserted directly into supraspinatus just above the scapular spine. results: the signal recovery from this set-up showed significantly higher performance compared with that obtainable with conventional instrumentation. conclusion: this system can provide a reliable and accurate clinical method for measuring muscle fatigue with fine wire emg from either deep or small muscles in shoulder and forearm. accurate measurement of upper limb fatigue is a great of importance for the assessment of muscle imbalance which is believed to be an important aetiologic factor for lateral and medial epicondylitis.