The condition mainly strikes women and can cause severe pain and tenderness in muscles, ligaments and tendons. Shoulder and neck pain is common but some people with fibromyalgia also have problems sleeping, and suffer anxiety and depression.
In their study of 33 women, the researchers had one group exercise in warm water for more than an hour three times a week for eight months while the others did no aquatic training.
The women who swam said the workouts helped ease their pain and they reported an improved quality of life, said Narcis Gusi at the University of Extremadura in Spain and Pablo Tomas-Carus of the University of Evora in Portugal, who conducted the study.
Read: What is fibromyalgia?
Swimming a cost-effective treatment
"The addition of an aquatic exercise programme to the usual care for fibromyalgia in women is cost-effective in terms of both health care costs and societal costs," they wrote in the journal Arthritis Research & Therapy.
Doctors usually prescribe exercise and relaxation techniques, painkillers or sometimes a low-dose antidepressant to treat the symptoms.
Read: Fibromyalgia - can diet help?
Pregabalin, a drug that calms nerve cells, gained US regulatory approval in June to treat the condition. It is sold as Lyrica by Pfizer Inc.
In November, US researchers showed that women who participated in a physical training regimen said they had less pain, better physical functioning and vitality.
Gusi and Tomas-Carus said they did not compare aquatic training with other forms of exercise such as low-impact aerobics, walking and tai-chi.
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