Muscle strength in healthy people and in patients suffering from recent-onset inflammatory arthritis

Abstract

Neuromuscular function was compared among 20 patients with relatively recent onset (symptomatic period 17 +/- 24 months) rheumatoid arthritis (RA) (experimental group; EG), and 20 age- and sex-matched healthy people (control group; CG). The comparison was repeated after a period of 6 months, when 16 patients had carried out progressive strength training. At baseline maximal grip strength and maximal dynamic unilateral strength of the knee extensors in the EG were significantly (P < 0.05) lower in comparison to the CG. The groups did not differ from each other in maximal isometric strength of the trunk flexors and extensors or the knee extensors. The 6-month dynamic strength training in the EG resulted in significant increases in maximal dynamic strength of the knee extensors (P < 0.001), in isometric grip strength (P < 0.001) and in isometric strength of the trunk flexors (P < 0.05) and extensors (P < 0.05) to the level of the healthy controls. Only minor changes took place in explosive strength and maximal isometric strength of the knee extensors. Erythrocyte sedimentation rate (P < 0.001), Ritchie's articular index (P < 0.01) and modified health assessment questionnaire (P < 0.01) improved significantly during the training period. The results suggest that inflammatory arthritis decreases dynamic and/or isometric muscle strength in selected muscle groups of the body already in the early stages of disease. However, progressive dynamic strength training rapidly increases the neuromuscular performance capacity of the patients even to the level of healthy people without detrimental effects on disease activity.