Patients will also be given a diary to take home to record details of any physiotherapy sessions they undergo outside the study (including any exercise they do at home) and any new symptoms that may arise. They will be asked to bring this diary to the remaining sessions. The patient will undergo 3 of these exercise sessions per week for 6 weeks (i.e. 18 exercise sessions altogether). The remaining 17 session will begin with application of the stimulator clip and the warm up as detailed above. At the end of the final exercise session, the scales used to measure arm strength and function, mood, fatigue and quality of life will be repeated.