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Effectiveness of Aquatic Exercises in Women with Rheumatoid Arthritis: A critical appraisal

Posted on December 6, 2018 by Ida Eriksmoen

Evidence Reviews
balloons floating on water

This blog is a critical appraisal of the following randomized controlled trial: Effectiveness of Aquatic Exercises in Women With Rheumatoid Arthritis: A Randomized, Controlled, 16-Week Intervention-The HydRA Trial.


Rheumatoid arthritis (RA) is a chronic autoimmune disease which causes inflammation of the joints. Typical symptoms of RA are pain, swelling and stiffness in the joints, and fatigue. RA may affect adults at any age, but starts most commonly in adults aged between 40 and 50. Women are affected more than men. Treatment options usually consist of medication, therapy, and/or surgery to correct any joint problems (Arthritisresearchuk.org, 2018) (nhs.uk, 2018). Hydrotherapy is used by some as treatment for RA, and involves special exercises carried out in a warm pool. The water supports the patient’s weight, and the heat is found to relieve arthritic pain (Arthritisresearchuk.org, 2018).

What was the study?

This study aimed to compare the effectiveness of water-based and land-based exercises in women with RA, assessing the outcomes of muscle strength (MS) in flexion and extension of the knee, disease activity, functional ability and body composition. The study recruited a total of 133 women, aged between 40 and 65 years, with a diagnosis of RA, all from the Rheumatic Diseases outpatient clinic in Sao Paulo, Brazil. 33 women were excluded for various reasons, and 100 were randomly allocated by a computerized randomization table into three groups; Land-based (LB), water-based (WB) and control group (CG). The LB performed only aerobic land-based exercises, while the WB only performed aerobic exercises in water, following the same protocol three times per week. The patients in the CG were instructed not to change their routines or participate in any other physical activities during the time of intervention. 18 patients were discontinued from the study due to poor adherence, loss of follow-up and 1 death. To minimise bias the data were analysed by intention to treat.

The groups were evaluated by a blinded physiotherapist and rheumatologist three times – the first time at randomization, then after 8 weeks of intervention and lastly at the end of 16 weeks. The main outcome measures for this study were a Biodex multi-joint system 3 PRO isokinetic dynamometer for muscle strength, Disease activity score 28 erythrocyte sedimentation rate for disease activity, Health Assessment questionnaire-modified to assess function and a whole body bone densitometry using a densitometer for body composition.

What were the results?

The study found that aquatic exercise had a significant improvement on disease activity and functional activity after 8 and 16 weeks in women with RA, as well as reduced daily intake of NSAID’s, compared to land-based exercise and control group. However, there was no significant increase in flexor and extensor MS of the knee or body composition.

Strengths and weaknesses

This study was a randomized controlled trial where randomization was carried out through a randomization table generated by a computer program, which is the ideal method of randomization. This ensures there are no systematic differences between the intervention groups that may affect the outcome of the trial. All three groups were similar and comparable at baseline, with no significant differences that could affect outcome. The sample size required was calculated to 27 patients in each group, in total 81 patients. 100 patients were recruited and randomized, which means the sample size reflects the target population more accurately, increasing the internal validity of the study.

However, the researchers have chosen to only include women with RA in this trial, which does not accurately represent the entire population of people with RA, meaining the outcome of this trial may only be generalized to women with RA. For this study to be representative for the entire population of patients with RA, the study should have included an equal amount from both genders.

Furthermore, the participants are only recruited from the Rheumatic Diseases outpatient clinic at Federal University of Sao Paulo in Brazil. There is evidence suggesting that lifestyle factors may affect inflammation and RA (Arthritisresearchuk.org, 2018). Recruiting patients from one clinic only affects the internal validity of the trial, increasing the risk of bias sampling towards the social class going to that clinic, which may have a different lifestyle to patients in other clinics.

By the nature of the interventions, neither physiotherapist nor patient could be blinded, increasing the risk of bias towards the care delivered by the physiotherapist as well as the patient’s motivation and expectations influencing outcome. To reduce the risk of bias and ensuring that all the patients were treated the same, the evaluator was blinded and a defined standard procedure was made for assessment which improves this trials internal validity. The study mentions a research protocol was made, and thoroughly explains the trial, allowing the trial to be reproduced.


The findings in this good quality randomised control trial suggest that water-based aerobic exercise is beneficial in treating women with RA regarding disease activity and functional ability. In order to change practice, further research must be done including a wider sampling and possibly including nutritional/lifestyle factors.


Arthritisresearchuk.org., 2018. What causes rheumatoid arthritis? | Arthritis Research UK. [online] Available at: https://www.arthritisresearchuk.org/arthritis-information/conditions/rheumatoid-arthritis/causes.aspx [Accessed 12 Jan. 2018].

Arthritisresearchuk.org., 2018. What is hydrotherapy? | Arthritis Research UK. [online] Available at: https://www.arthritisresearchuk.org/arthritis-information/therapies/hydrotherapy/what-is-hydrotherapy.aspx [Accessed 12 Jan. 2018].

Arthritisresearchuk.org., 2018. What is rheumatoid arthritis? | Arthritis Research UK. [online] Available at: https://www.arthritisresearchuk.org/arthritis-information/conditions/rheumatoid-arthritis/what-is-rheumatoid-arthritis.aspx [Accessed 12 Jan. 2018].

nhs.uk., 2018. Rheumatoid arthritis. [online] Available at: https://www.nhs.uk/conditions/rheumatoid-arthritis/ [Accessed 11 Jan. 2018].

Siqueira, U., Orsini Valente, L., de Mello, M., Szejnfeld, V. and Pinheiro, M. 2017. Effectiveness of Aquatic Exercises in Women With Rheumatoid Arthritis. American Journal of Physical Medicine & Rehabilitation, 96(3), pp.167-175.


Ida Eriksmoen

Physiotherapy student at Queen Margaret University, Edinburgh View more posts from Ida

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