Exercise as it relates to Disease/Effectiveness of resistance training in patients living with psoriatic arthritis

An critical analysis of the journal article “A resistance exercise program improves functional capacity of patients with psoriatic arthritis: a randomized controlled trial” by Roger-Silva, Natour, Moreira & Jennings.

What is the background of this research?
Psoriatic arthritis (PSA) is a chronic inflammatory disease that affects the joints, organs, skin, and nails. It is characterised by pain and fatigue which limits functional capacity and reduces patients’ quality of life. Disease activity causes comorbidities, such as cardiovascular disease and increases mortality rates within the population. It is well established that physical activity (PA) mitigates many health conditions; however little research has been conducted on the affect PA has on PSA. This research was conducted to evaluate whether resistance training (RT) can improve disease activity, functional capacity, and quality of life in people diagnosed with PSA.

Where is the research from?
The research was conducted by Diego Roger- Silva, Jamil Natour, Emilio Moreira, and Fabio Jennings. The authors were associated with the Rheumatology Division of University Federal de São Paulo in Brazil at the time. The article was originally published in November 2017 by Clinical Rheumatology, a journal with an impact factor score of 3.650. This in within the top 20-40% of Journals within the same discipline.

Table 1: Data from SCI Journal

What kind of research was this?
This was a blinded randomised control trial, that involved the use of several questionnaires and the 1 repetition max (1RM) test to assess results.

What did the research involve?
Participants were recruited from the outpatient clinic of the authors institution and via advertisement. Patients deemed incapable of undertaking a RT program were excluded, as were those with a history of regular exercise. 41 male and females aged between 18-65, diagnosed with PSA and on stable pharmaceutical treatment were recruited. The participants were randomly assigned electronically to the intervention group (IG) or control group (CG). 20 participants were assigned to the IG while the other 21 participants formed the CG. The division of groups was homogenous.

The IG completed a 12-week RT program. The program involved completing two exercises for major muscle groups and one exercise for smaller muscles, twice a week. The load prescribed was 3 sets of 12 repetitions at 60% of 1RM, with 1–2-minute rest intervals. The CG were advised to maintain their daily activities and usual treatment, and to avoid commencing new non-pharmaceutical treatment. Questionnaires were utilised to assess participants functional capacity, disease activity, and quality of life. Strength was assessed using the 1RM test. The blinded evaluator assessed participants prior to randomisation, then at 6 and 12 weeks. Outcomes were analysed using ANOVA software.

What were the basic results?
Disease activity was significantly reduced in the IG, according to the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and the Disease Activity Score 28 (DAS 28). However, only the BASDAI results were found to be statistically meaningful when compared intergroup.

Functional capacity was found to be significantly increased in the IG, according to the Bath Ankylosing Spondylitis Functional Index (BASFI) and Health Assessment Questionnaire (HAS-Q). Compared intergroup, only the HAS-Q results were statistically relevant. Interestingly the BASDAI, BASFI and HAS-Q found that disease activity and functional capacity in the CG worsened marginally over time.

Quality of life was assessed using the Medical Outcome Study Short Form Health Survey (SF-36). The IG reported statistically significant improvements in the domains of pain, general health, vitality, and in social, emotional, and physical aspects. Although, the only domains that were meaningfully different intergroup were pain and general health status. Mental health improved marginally, over the trial in both groups. The CG demonstrated significant improvements in the emotional domain however other areas remained relatively unchanged.

The 1RM test revealed that in most exercises, both groups achieved statistically significant improvements in strength. The only exercises where the IG improved and the CG did not, were the front pull, triceps pulley and gluteal exercises. Although when compared intergroup the differences were not significant. The bicep exercises were the only exercises that both groups failed to demonstrate meaningful results. Whereas the right leg extensor was the only exercise where the IG demonstrated a significantly greater improvement than the CG.

What conclusions can we take from the research?
RT may significantly reduce disease activity, increase functional capacity, and improve general health and pain levels. However, several limitations to the research should be considered. As the questionnaires were translated into Portuguese its likely English is not the authors first language. This may explain why grammatical errors made sections of the article difficult to understand and lacked important details. It was unclear whether the IG were supervised or whether they continued with pharmacological treatment. It also wasn’t clear whether the CG were instructed to refrain from commencing RT.

Furthermore, elements of the research design may have resulted in subjects being susceptible to an issue known as a demand characteristic. This occurs when subjects respond in a way that they believe supports the purpose of the study. As the participants had knowledge of the project, it’s conceivable that their behaviour and responses were inadvertently influenced. Supporting this theory is the fact that both groups increased their strength during the trial period. This may indicate the CG changed their usual activity during the trial. Despite this, the questionnaire responses were vastly different.

Another possibility for the disparity in responses could be due to another issue known as a placebo characteristic. The IG may have felt greater benefits just from knowing they were receiving the intervention.

As to date, this study appears to be the only research of its kind. Despite the power of the study meeting the minimum of what is typically acceptable, without comparing results to other research the credibility of the study is compromised. To compensate a larger cohort and longer time frame would have bolstered results. Considering the limitations of this study, it is difficult to draw conclusions from the results and they should be interpreted with caution. Having said that, the authors found the intervention to be effective.

Practical Advice
Despite the limitations of this study, PA including RT is well established to have a multitude of health benefits. The Australian Governments’ PA and exercise guidelines recommend that all people, including those with disability and chronic health conditions, engage in an appropriate level of PA. Prior to commencing an exercise program, it is recommended to speak with a doctor. Working with a qualified professional who can develop and implement an exercise program, such as an Exercise Physiologist can assist to manage exercise safely. People who meet the NDIS eligibility requirements may be able to have therapy funded.

Further information/Resources
The following websites provide information related to accessing support for those living with PSA.


 * https://www.mypsoriaticarthritis.org.au/
 * https://creakyjoints.org.au/living-with-arthritis/new-interactive-website-for-australians-with-psoriatic-arthritis/
 * https://arthritisaustralia.com.au/get-support/find-support-near-you/