This was a single-blinded, randomized parallel study. Eighty-two patients presenting chronic musculoskeletal shoulder pain were allocated to two groups. Patients in group 1 (n= 41) received a five-series Isometric Contraction of shoulder external rotators at 20% maximal voluntary isometric contraction, while patients in group 2 (n= 41) received similar protocol but the intensity of contraction was set at 80% maximal voluntary isometric contraction. In both cases, each series of IC was done until exhaustion or up to a maximum of 5 minutes. Patients received five sessions of treatment during a two-week period. Outcome measures included muscle pain sensitivity (pressure pain thresholds) and pain intensity (pain intensity numerical rating score), and shoulder function (Constant Score).
The aim of this study was to evaluate the influence of the intensity of Isometric Contraction of shoulder external rotators, comparing the effect of a high-level IC (80% maximal voluntary isometric contraction) versus a low-level Isometric Contraction (20% maximal voluntary isometric contraction) on pain intensity, pain thresholds, and function in chronic pain shoulder patients.