Exercise as it relates to Disease/Combating Cardiovascular Disease in Rheumatic Patients: is High Intensity Interval Training (HIIT) your new defence?

This Wikibooks page is a critical appraisal of the following research including a summary, critique and conclusion.

Research: Sandstad, J., Stensvold, D., Hoff, M., Nes, B., Arbo, I. and Bye, A. (2015). The effects of high intensity interval training in women with rheumatic disease: a pilot study. European Journal of Applied Physiology, [online] 115(10), pp. 2081-2089. doi:10.1007/s00421-015-3186-9

What is the background to this research?
[[File:Rheumatoid arthritis world map - DALY - WHO2004.svg|thumb|Rheumatoid arthritis world map

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Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease, affecting 0.5 - 1% of adults globally. The disease is 50% more frequent in females and onset is most prevalent in middle age, between 40 – 65 years of age. This study looks at rheumatic disease, primarily RA and juvenile idiopathic arthritis (JIA) which is an umbrella term for arthritis with onset before 16 years of age. RA is the most common systemic inflammatory arthritis with symptoms including, but not limited to, restricted mobility, joint pain and stiffness, increased risk of cardiovascular and pulmonary diseases, increased risk of psychosocial and skeletal disorders and premature death. The risk of early mortality has been strongly associated with cardiovascular diseases (CVD) presumably due to the chronic inflammation, pain and subsequent physical inactivity. Regular exercise is included as an important component of treatment for rheumatic patients, as it induces anti-inflammatory effects and reduces the risk of CVD. As RA and other rheumatic disease largely effects the musculoskeletal system, health professionals have previously maintained that heavy exercise may have adverse effects on the disease: worsening symptoms and furthering joint damage by placing additional strain on the joints. HIIT is recognised to substantially improve VO2 max which is considered the best predictor of CVD morbidity, thus it is important to consider the use of HIIT in rheumatic patients, despite general practitioners previous recommendations. This study looks at the use of HIIT to lower CVD risk and any adverse effects it may have on inflammation and other rheumatic symptoms, aiming to provide essential information for disease sufferers.

Where is the research from?
The research was conducted by members of the Faculty of Medicine from the Norwegian University of Science and Technology (NTNU) and a rheumatologist from St. Olavs Hospital. The Norwegian Health Association, Revmafondet which is the foundation for rheumatic disease in Norway and the Liaison Committee between the Central Norway Regional Health Authority (RHA). The study was approved by the regional ethical committee.

What kind of research was this?
This pilot study was an investigative exercise intervention: a randomised, controlled cross-over trial where the participants acted as their own controls throughout the study.

Table 1. Comparative Analysis of Cross-Over Trials
For more information see: Jones & Kenward, 2003 "Design and Analysis of Cross-Over Trials, Second Edition"

What did the research involve?
The study consisted of recruiting the participants through advertisement in a local newspaper, the university website (NTNU) and posters at St. Olavs University Hospital. The participants were then randomised to begin in the intervention group or in the control group. During the control period participants were instructed not to alter their normal routine. The intervention consisted of participants performing HIIT which involved 4 by 4 minute intervals at 85 - 95% of their maximal heart rate twice per week for 10 weeks on spinning bikes. Measurements and tests were conducted before and after each 10-week period of training or control and included their maximal oxygen uptake, heart rate recovery, blood pressure, body composition and blood variables. Before participation in the second period (training or control) commenced the subjects were given 2 months break to reduce the risk of carry-over from the intervention.

What were the basic results?
The results indicated that HIIT produced a substantial improvement in many risk factors for CVD without a subsequent increase in disease activity or inflammation. There was further indication that the intervention resulted in a decline in overall inflammation. The participants' cardiorespiratory ability improved, body fat percentage and waist circumference was reduced, all of which are known risk factors for CVD.

How did the researchers interpret the results?
The study correlated general improvements found in fitness and body composition and decreased risk of mortality and risk of CVD. Blood pressure, inflammatory biomarkers, body composition, cardiovascular and respiratory improvements indicate a largely decreased risk of both CVD factors and mortality overall.

The researchers also discussed that the intervention did not result in adverse effects relating to disease activity or inflammation and a trend was found toward decreased general inflammation following the intervention.

It is possible that with such a low sample size the results were skewed. The disadvantages cited in Table 1. outline limitations of using a cross-over design and in this case it is possible that the subjects who participated in the intervention initially may experience some long-term benefits to the training relating to healthier lifestyle choices during the following control period.

What conclusions should be taken away from this research?
This research bolsters previous conceptions that HIIT lowers the risk factors for CVD. This is especially important for rheumatic patients where CVD is responsible for 40% of early mortality and is the leading cause of death.

What are the implications of this research?
The main findings of this study indicate that further research needs to be done into the effects of HIIT on rheumatic disease, preferably with a larger sample size. The benefits may be more substantial than just preventing or lowering the risk for CVD. This type of training has known benefits for general health and the prevention of many other systemic diseases.

The research specifically denotes that JIA is poorly described due to an absence of research and a lack of understanding of the pathology. It would be therefore difficult for the research to provide recommendations specific to this subset of RA.

This study aims to investigate the effect of HIIT on rheumatic patients, however only includes female participants and two different types of rheumatic disease, RA and JIA. It is specifically a pilot study and therefore does recommend a replication with a larger sample size and male participants. However, many results are generalised to rheumatic patients in general, when the research only tests RA and a single subset.