Effectiveness of hippotherapy and therapeutic horseback riding on balance in hemiparetic patients after stroke

Introduction: Stroke is one of the leading causes of disability and death worldwide. Individuals who suffered stroke present numerous functional limitations. Hippotherapy (HPOT) is proposed as capable of promoting the recovery of postural balance in patients with neurological impairment. Objective: To analyze published articles, seeking the effects of HPOT on changes in postural balance, through the Berg Balance Scale (BBS), in individuals with stroke. Methods: We conducted a systematic review and meta-analysis of studies published on the electronic databases PubMed, VHL, SCIELO, Cochrane, SCOPUS, WoS, and Cinahl. Keywords: "hippotherapy", "horseback riding" and "stroke" linked by the OR and AND boolean operators. The research was restricted to clinical trials in an adult population with a history of stroke. Results: Four articles were included in this meta-analysis, which used HPOT as an intervention to improve postural balance. Three studies used a mechanical device (horseback riding), and the horse. The age ranged from 61 to 71 years, being more predominant the male sex. Sessions ranged from 6 to 12 weeks of 20 to 30 minutes per session. Quality analysis using the PEDro scale demonstrated scores ranging from 6 to 8 points in the selected studies. Overall, treatment with mechanical and conventional therapy resulted in an improvement in the total BBS score. As compared with conventional therapy just studies with horseback riding was superior to conventional therapy to improve postural balance in hemiparetic stroke patients. Conclusion: There are few studies of high quality; then, it is not possible to evaluate the effectiveness of HPOT using a horse or a mechanic simulator in patients with stroke when compared with conventional therapy. Future studies could clarify if HPOT has potential benefits as a complementary therapeutic strategy to conventional physiotherapy to promote the improvement of postural balance after stroke.


Introduction
The neurological deficit from stroke results from the central nervous system injury of vascular origin due to a lack of tissue oxygenation. 1 It is the most prevalent cause of disability and death worldwide, and its incidence increased around 42% in the world population between the years 1990 and 2010. The number of deaths and disability due to this disease increased by approximately 20% and 16%, respectively. 2 In Brazil, according to statistics from 2016, the number of deaths caused by stroke was 102,965, of which 51,753 were deaths in men and 51,198 in women. 3 The prevalence of disability after stroke was 29.5% for men and 21.5% for women in 2013. 4 Mortality and disability rates are at least ten times higher in lowand middle-income countries than in economically more developed nations. One of the reasons for this is the lack of disease monitoring and rehabilitation programs. 5 Survivors from stroke commonly have disabilities associated with impairments, especially motor impairments, which are the most prevalent. 6 Limitations on mobility, particularly in postural balance, are associated with low ambulatory activity and low levels of cardiovascular fitness, and balance-related inactivity could contribute to deconditioning. 7 Participation and autonomy five years after stroke are limitated on domains that required high levels of physical, social, and cognitive abilities.  There is strong evidence in favor of high repetitive task-oriented and task-specific training. 13 Although, systematic reviews identified limited evidence based

Research strategy
We could describe the research question of this systematic review using the PICO acronym as This systematic review follows recommendations of Cochrane handbook 24 and attended the criteria described in the items of reports for systematic reviews (PRISMA). 25 The protocol was registered in the database PROSPERO under the number: CRD42018083647.

Purpose of the evaluation criteria
The review focused on published studies in any language, with no time limit, in a population of adults diagnosed with a stroke. Changes on postural balance were the outcome do evaluate the results of hippotherapy. The studies included reliable assessment tools to avoid bias risks. All studies analyzed were randomized clinical trials.

Data source
We searched the following electronic databases: Pubmed ( to 2017). The keywords used were "hippotherapy", "horseback riding," and "stroke" and "balance", "postural balance" linked by booleans operators OR and AND.

Types of intervention and outcomes
The intervention considered in the experimental group was hippotherapy with horses or mechanical device (horseback riding) that reproduced the three-

Data extraction
All data relevant to the study were extracted. A single researcher performed the extraction procedure, and a second researcher examined them.

Data analysis
As mentioned above, the variable of interest used on meta-analysis was the total score of BBS using the means and standard deviation of group control and intervention (hippotherapy). The BBS total score was analyzed as a continuous data.
As all the pooled studies used the same evaluation scale to analyze the result, the mean differences (DM) with 95% confidence interval (CI) were calculated.
The heterogeneity was evaluated through the value of the I² statistic, with a value less than 50% indicating low heterogeneity. If there were acceptable levels of heterogeneity, the fixed-effect model would be used instead of the random one. 24 All statistical analyzes were performed with R Software -Meta Package.

Selection and evaluation of studies
The initial survey resulted in 69 articles. Initially, 36 searches that repeatedly appeared in more than one  In the isolated analysis, the study that used the horse as a therapeutic resource did not present a significant difference between the control and intervention groups (1 study, n = 30 patients, WMD = 1, 95% CI: 2.5, 4.5).     There is a considerable difference between the intervention in the control group across the four studies.

Conclusion
Since there are few studies of high quality, it is not possible to evaluate the effectiveness of hippotherapy and horseback riding in patients with stroke. The motor performance improved on three studies using horseback riding and on the study using hippotherapy.
Future studies could clarify if the hippotherapy is a complementary therapeutic strategy to conventional physiotherapy to promote the improvement of postural balance.

Authors´ contributions
SBCAS and ACCBH were responsible for the conception and design, and data acquisition. JCL, for the analysis and interpretation of data. MLS, for the