Evidence on the effects of exercise therapy in the treatment of chronic disease U M Kujala Department of Health Sciences, University of Jyva ¨skyla ¨, Jyva ¨skyla ¨, Finland Correspondence to: U Kujala, Department of Health Sciences, University of Jyva ¨skyla ¨, PO Box 35 (LL), FIN- 40014, Finland; urho.kujala@ sport.jyu.fi Accepted 23 April 2009 Published Online First 29 April 2009 ABSTRACT Evidence on the effects of exercise in the treatment of patients with chronic diseases should be based on well designed randomised controlled trials. The most consistent finding of the meta-analyses summarised in the present work is that aerobic/functional capacity and muscle strength can be improved by exercise training among patients with different diseases without having detrimental effects on disease progression. This is important, as with population aging exercise therapy may be an important means of reducing disability and increasing the number of older people living independently. Additionally, there is accumu- lating evidence that in patients with chronic disease exercise therapy is effective in improving the prognostic risk factor profile and, in certain diseases, in delaying mortality. In some diseases, such as osteoarthritis, pain symptoms may also be reduced. Severe complications during the exercise therapy programs were rare. Conclusive evidence as to the benefits of exercise in the treatment of patients with chronic diseases within the limited resources of the healthcare system should be based on well designed randomised controlled trials (RCTs). These in turn should be based on a plausible account of how (via what mechanisms) exercise benefits the patient. As patients with chronic diseases may be at risk for exercise-related cardiovascular or other compli- cations, doctors often need to issue such patients with guidelines for a safe training program. Exercise therapy for chronic diseases can be either generalised aerobic or strength training or condition-specific training. A typical example of generalised training is aerobic or strength training causing systemic effects, such as that on insulin sensitivity in the treatment of type 2 diabetes mellitus. Condition-specific training may include, for example, a series of specific movements with the aim of promoting good physical health, such as strengthening the low back muscles in patients with low back pain or pelvic floor muscle training in patients with urinary incontinence. Recently, the number of RCTs evaluating the effects of physical exercise therapy in the treat- ment of specific diseases and related functional impairments has increased substantially allowing systematic reviews including meta-analyses. This review summarises the evidence so far on the effects of exercise therapy in the treatment/ rehabilitation of different chronic diseases. METHODS Search strategy and selection criteria This paper is a summary of the evidence to date from systematic reviews of at least three randomised controlled trials investigating the effect of exercise therapy on the same outcome among patients with the same chronic disease. For studies to be included in this summary review, the intervention and the control groups had primarily to be contrasted by exercise (most commonly exercise training + usual care vs usual care). This review is based on previous repeated searches of the literature 1 and contacts with the authors of different systematic reviews. For this update review, final literature searches of computer databases (PubMed, Cochrane Database of Systematic Reviews) were performed for the period from January 2001 up to and including December 2008. Reviews that were not updated after the year 2000, non-systematic reviews, reviews on non- randomised trials and systematic reviews on exercise in the rehabilitation of acute injuries or musculoskeletal surgery were not included. Obesity was not considered as a disease in this review. Due to the large number of outcome variables only the clinically most important out- comes are included; these were selected on the basis of the author’s clinical experience and contacts with different specialist doctors or scien- tists. Findings which lack a plausible explanation of the possible mechanisms underlying the effec- tiveness of the exercise therapy or which lack statistical power are not reported systematically in this review. In systematic reviews the results can be given using different qualitative or quantitative (meta- analyses) techniques. For the most part, this summary review is based on the results of meta- analyses (table 1). Meta-analyses draw on a variety of techniques. The choice of technique depends on the nature of the data being analysed. For dichotomous (or binary) data the most commonly used summary statistics in exercise therapy studies are pooled odds ratios (ORs) or relative risks (RRs). For continuous data, whenever outcomes are measured in a standard way across studies, the weighted mean difference (WMD) is preferable. Where continuous outcomes are conceptually the same but measured in different ways, such as different pain scores in osteoarthritis, the results can be summarised using standardised (for stan- dard deviations in the outcome measure) mean differences (SMDs). In cases where the data available do not enable statistical pooling, qualita- tive analysis is performed. In this article, categories of levels of evidence are not systematically reported, but the effects of exercise therapy are quantified as reported by the authors of specific meta-analyses. Review 550 Br J Sports Med 2009;43:550–555. doi:10.1136/bjsm.2009.059808 on September 8, 2021 by guest. Protected by copyright. http://bjsm.bmj.com/ Br J Sports Med: first published as 10.1136/bjsm.2009.059808 on 29 April 2009. Downloaded from