Muscles and nerves of the human body represent a source of electric energy. Changes in the electric current inside the skeletal muscle can be detected using electromyography (EMG). EMG can be differentiated into needle EMG and surface electromyography (SEMG). Needle EMG and SEMG are both diagnostic methods. They help the clinician to determine whether a patient is being affected by a myopathic or a neuropathic disorder. In this paper, the physiology of the muscular contraction process is firstly explained in detail. Later on, the process of how the EMG sensors register and convert the electric current produced within the muscle into a graphic report are explained as well. Furthermore, this paper describes both the advantages and disadvantages of EMG and SEMG. Also, the indications and the properties of these diagnostic methods in a clinical setting are described. This paper also describes the current guidelines for the correct placement of SEMG electrodes on the skin. In addition, several new potential clinical applications for SEMG are described. A commercially available SEMG, the MyoArmband SEMG sensor (Thalmic Labs Inc., Kitchener, Ontario, Canada), is introduced in this paper and represented with its' advantages and disadvantages. Publications concerning the MyoArmband SEMG sensor which support the aforementioned advantages are further discussed. Later, potential clinical applications which tend to prove the therapeutic and diagnostic uses of the MyoArmband SEMG sensor are presented. Among these, biofeedback therapy together with qualitative measurement of muscle fatigue and contraction emergence latency measurement seem to have the best perspective. Altogether, this device, as well as SEMG procedure in general, hold great perspective for clinical use. Due to the non-invasive nature of the device application, paediatric patients would merely benefit from such biofeedback therapy.