The effects of different training programs on the trapezius muscle of women with work-related neck and shoulder myalgia

The aim of this study was to examine the effects of training on the structu ral characteristics of the trapezius muscle in women with work-related trap ezius myalgia. Muscle biopsies were taken before and after 10 weeks of thre e different training programs (strength, endurance and coordination). Enzym e-immunohistochemical analysis was performed to assess muscle fibre types, fibre area, capillary supply and cytochrome c oxidase (COX) activity. There was an increase in the proportion of type LIA fibres in strength trained g roup (P < 0.05). Strength training elicited a preferential increase in the area of type II fibres (P < 0.05); both strength and endurance programs ind uced an increase in the number of capillaries around type I and IIA muscle fibres. Finally, all training programs induced a decrease in the proportion of COX-negative fibres. In conclusion, the trapezius muscle of women with neck and shoulder myalgia is characterised by a great potential of adaptati on to physical exercise over a period of 10 weeks. The significant changes in the number of capillaries and the specific changes induced by training a t the level of muscle fibres might well explain the improvement of muscle f unction.