Improvements of muscle strength predicted benefits in HRQOL and postural balance in women with fibromyalgia: an 8-month randomized controlled trial

Objective. To evaluate whether changes in muscle strength due to 32 weeks of supervised aquatic training predicted improvements on health-related quality of life (HRQOL). Methods. Thirty women with FM aged 50.8 +/- 8.7 years were randomly assigned to an experimental group (n=15), performing 3 weekly sessions of 60 min of warm-water exercise; or to a control group (n=15). HRQOL was evaluated using the Short Form 36 Health Survey (SF-36). Maximal unilateral isokinetic strength was measured at 60 degrees/s and 210 degrees/s in the knee extensors and flexors in concentric action and at 60 degrees/s in knee extensors eccentric action. Postural balance was evaluated using the one-leg stance, eyes closed. Results. After 32 weeks of water exercise therapy, statistically significant improvements occurred in concentric knee flexors and extensors strength at 60 degrees/s, in eccentric knee extensors and in postural balance. The treatment led to additional improvements in physical function, role physical problems, body pain, general health, vitality, role emotional problems and mental health dimensions of SF-36. Gains in the concentric knee flexors strength predicted improvements in role of physical problems, whereas those in concentric knee extensors did the same for mental health and role emotional problems. Gains in eccentric knee extensors strength predicted improvements in postural balance. Conclusions. A long-lasting exercise therapy in warm water produced relevant gains in muscle strength at low velocities of movements, some of which predicted improvements in physical problems, emotional problems, mental health and balance. Trial registration. International Standard Randomized Controlled Trial Number ISRCTN53367487, information available in http://www. controlled-trials.com/ISRCTN53367487.