The Effectiveness of Isometric Exercise on the Management of Chronic Shoulder Pain

The Influence of the Intensity of Isometric Exercise on Pain Intensity, Muscle Pain Sensitivity and Function in Patients With Chronic Shoulder Pain: A Parallel Single-blind Randomized Study

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.

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).

Inclusion Criteria:

• Male or female having a chronic shoulder soft-tissue injury of at least 3 month duration resulting in a mild to moderate level of disability (Constant score scale), pain intensity score between 3 and 8 points (pain intensity numerical rating scale), and age between 18 and 65 years.

Exclusion Criteria:

• Participants were excluded if they had any contraindications related to the application of isometric exercise, neurological problems (central or peripheral), concomitant physiotherapy or chiropractic treatment, fibromyalgia or general systemic disease conditions, had participated in any moderate or vigorous physical activity in the las 72 hours previous the outcome assessment.