Fibromyalgia is a disease whose incidence rate is increasing and causing a severe disability to those who suffer it. Currently, other treatment resources are being implemented, such as aquatic therapy. This therapy seems to provide positive results in different dimensions of fibromyalgia.

The main objective of the study is to determine the effectiveness of a physical therapy program in warm water vs. land-based therapy in women with fibromyalgia for pain reduction and improvement balance at the end of treatment and a month and a half later (follow-up).

The type of study is a randomized controlled opened trial. The sample is composed of 34 women with age between 35 and 64 years and fibromyalgia diagnosis who will be divided into 2 groups: Aquatic Therapy Group (n=17) and Land-Based Therapy Group (n=17). This study will have two primary outcomes: Pain and balance. The intensity of pain will be assessed using the visual analog scale (VAS) and the pain threshold for each one of the 18 tender points will be assessed using a electronic algometer. Static balance will be evaluated with the Romberg's test and the dynamic balance with the Timed Up & Go test (TUG) and Berg Balance Scale. Both type of balance will be recorded in slow motion and then, will be analysed with a motion software. Secondary outcomes are: The impact of fibromyalgia on patient's lives, that will be measured with the "Revised Fibromyalgia Impact Questionnaire" (FIQR); the sleep quality, that will be assessed with the "Pittsburgh Sleep Quality Index" (PSQI); the fatigue, that will be evaluated witn the "Multidimensional Fatigue Inventory" (MFI); the physical capacity, that will be measured with the "six minute walk test" (SMWT) and confidence in balance that will be assessed with the "Activities-specific Balance Confidence" scale (ABC).

Each intervention will last one hour and will be made 3 times a week for three months . It will consist of 4 sections: Warming, exercises for static and dynamic balance training, stretching and relaxation. Statistical analysis will be made using the Statistical Package for the Social Sciences software, version 21.0 for Windows. p ≤ 0.05 will be the significance level set for all analysis.

Inclusion Criteria:

• Female.
• Age range between 35 and 64 years.
• Diagnosis of fibromyalgia according to the criteria of the American College of Rheumatology (ACR) in 1990 and 2010.
• Mark ≥ 4 on the Visual Analogue Scale (VAS).
• Mark ≥ 5 on the Visual Analogue Scale for balance included in The Revised Fibromyalgia Impact Questionnaire (FIQR).

Exclusion Criteria:

• History of severe trauma.
• Neurological diseases (stroke, Parkinson's disease, dementia).
• Frequent migraines.
• Inflammatory rheumatic diseases.
• People who have been treated in the past six months by traumatic injuries.
• Being pregnant.
• Visual or hearing deficits uncorrected.
• Infectious diseases.
• Severe cardiovascular disease.
• People who do exercise regularly more than 20 minutes, more than 3 times a week in the past 3 months.