MUSCLE STRENGTH IN HEALTHY PEOPLE AND IN PATIENTS SUFFRING FROM RECENT-ONSET INFLAMMATORY ARTHRIRIS

Neuromuscular function was compared among 20 patients with relativelyrecent onset (symptomatic period 17 ± 24 months) rheumatoidarthritis (RA) (experimental group; EG), and 20 age- and sex-matchedhealthy people (control group; CG).The comparison was repeatedafter a period of 6 months, when 16 patients had carried outprogressive strength training. At baseline maximal grip strengthand maximal dynamic unilateral strength of the knee extensorsin the EG were significantly (P < 0.05) lower in comparisonto the CG. The groups did not differ from each other in maximalisometric strength of the trunk flexors and extensors or theknee extensors. The 6-month dynamic strength training in theEG resulted in significant increases in maximal dynamic strengthof 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 thehealthy controls. Only minor changes took place in explosivestrength and maximal isometric strength of the knee extensors.Erythrocyte sedimentation rate (P < 0.001), Ritchie's articularindex (P < 0.01) and modified health assessment questionnaire(P < 0.01) improved significantly during the training period.The results suggest that inflammatory arthritis decreases dynamicand/or isometric muscle strength in selected muscle groups ofthe body already in the early stages of disease. However, progressivedynamic strength training rapidly increases the neuromuscularperformance capacity of the patients even to the level of healthypeople without detrimental effects on disease activity. KEY WORDS: Recent-onset inflammatory arthritis, Muscle strength, Neuromuscular function, Strength training, Disease activity, Healthy people