The effect of exercise on neck-shoulder pain was studied in 103 women with work-related trapezius myalgia randomized into three exercise groups and a control group. One group trained strength, the second muscular endurance and the third co-ordination. The exercise groups met three times weekly for 10 weeks. Pain assessment was made on three visual analogue scales, indicating pain at present, pain in general and pain at worst. Pain thresholds were measured in the trapezius muscle with a pressure algometer. A pain drawing was completed. The rated pain decreased significantly (P<0.05) on the VAS describing pain at worst in the strength and endurance groups. Pressure sensitivity decreased significantly (P<0.05) in four triggerpoints in the exercise groups. No changes were seen in the extent of painful body area in any group. Comparison of exercisers (n=82) and controls (n=21) showed significantly larger pain reductions on VAS pain at present and VAS pain at worst among exercisers. All three exercise programs showed similar decreases of pain which indicates that the type of exercise is of less importance to achieve pain reduction.

Myalgia localized to the neck and shoulder in women is a growing problem both in the general population and in the industrial world. The aim of this study was to investigate the mechanisms involved in work-related myalgia. In 21 women (age, 38.7+/-5.5 years), muscle biopsies were obtained from the upper part of the trapezius and the morphologic and metabolic characteristics of muscle fibres were analyzed. The patients indicated the number of painful areas on a pain drawing and the intensity of pain was assessed using a visual analogue scale (VAS). Two groups were formed on the basis of the median values: lower pain level and higher pain level. Trapezius muscles were characterized by the large size of type I fibres and the low capillary to fibre area ratio for both type I and type IIA fibres. Patients with the highest pain scores had the lowest capillary to fibre area ratio for type I fibres (coefficient correlation r = -0.45 and P < 0.05). Moreover, the proportion of cytochrome c oxidase (COX)-negative fibres seen in the cross-sections was significantly higher in the group of patients which had the higher pain and more painful areas than in the group of patients with lower pain level and painful areas (P < 0.05). The significant increase (P < 0.05) of the size of the type I fibres in trapezius myalgia point to the special strain imposed upon type I muscle fibres during work tasks. Cytochrome oxidase c deficiency which is indicative of an energy crisis within muscle cells and the low capillary to fibre area ratio which might impair oxygen delivery and removal of metabolites in the working muscles are both associated with pain in the trapezius muscle.

To compare training programs for women with trapezius myalgia regarding physical performance and pain, 102 women were randomized to strength, endurance, co-ordination and non-training groups. Before and after the intervention, static strength and dynamic muscular endurance in shoulder muscles were measured on a Cybex II dynamometer. Muscle activity in shoulder muscles was monitored via surface EMG. The signal amplitude ratio between the active and passive phase of repeated contractions indicated the ability to relax. Pain at present, pain in general and pain at worst were measured on visual analogue scales. After training, within group comparisons showed that the training groups rated less pain, and in the strength training group ratings of pain at worst differed from the non-training group. Using the non-training group as a reference, static strength increased in the strength and endurance training groups and muscular endurance in all training groups. The study indicates that regular exercises with strength, endurance or co-ordination training of neck/shoulder muscles might alleviate pain for women with work-related trapezius myalgia.

Grip strength assessment in children with Grippit results in good relative and absolute reliability for peak and sustained grip strength. We recommend that three test trials are used. The mean of and the best of three trials are comparable.