Abstract

Role of exercise in chronic disease management

Traditionally physical activity has been regarded as a powerful tool in the prevention of many chronic diseases. It has been widely accepted that an epidemiological observational study with supportive data from studies on disease mechanisms give enough evidence for exercise recommendations in disease prevention. Final evidence for the benefits of exercise in the treatment of patients with chronic disease using limited resources of health care system should optimally be based on well designed randomized controlled trials (RCTs). Recently, the number of RCTs evaluating the effects of physical exercise therapy in the treatment of specific diseases has increased substantially.

The most consistent finding of the studies is that exercise capacity or muscle strength can be improved among patients with different diseases without causing detrimental effects on disease progression (Kujala 2004). Severe complications in the exercise trials were rare. In some diseases, such as osteoarthritis, pain symptoms may also be reduced. The majority of the RCTs are of a too short duration to document disease progression. Studies on patients with coronary heart disease as well as studies on patients with heart failure show that exercise groups have somewhat reduced all-cause mortality. The clinically very significant findings include that exercise therapy has beneficial effects on all metabolic syndrome components and is highly beneficial for the patients with type 2 diabetes mellitus.

Before interpreting detailed results of studies, critical analysis of the methodological quality of the individual RCTs is important. Also, we have to keep in mind that generalizability may be a problem while some RCTs include patients that are not representative of the general population of patients as regard to age and coexisting diseases.

The fact that most trials are of short duration means that some benefits, such as increases in physical fitness, are reached within some weeks or months. However, the duration of specific RCTs usually is too short to give final evidence on the effects of exercise therapy on the true progression of disease. RCTs on the effects of exercise on the lipid risk factors, blood pressure levels, glucose homeostasis, as well as sporadic long-term follow-ups of disease progression support the conclusion that exercise therapy may have a beneficial effect on the long-term progression of specific diseases. However, there is a need for RCTs with long-term follow-ups including documentation of such outcomes as survival rate, hospitalization rate, and health care costs.

Physicians prescribing exercise therapy have to know basics of exercise physiology and training principles. Also, tailoring of a program depends on the disease and its stage, baseline fitness level of the patient, and goals of the program set together with the patient.

The available RCTs include rather large variety of effective training programs. Majority of the patients seem to benefit from low to moderate intensity aerobic exercise. Based on the available RCTs detailed conclusions on the dose-response of exercise therapy in the treatment of specific diseases can not be done. We have to remember that beneficial results of exercise therapies for patients with chronic disease shown by RCTs are based on carefully planned and followed exercise interventions among patients whose clinical status has first been examined to take into account possible risks. Unlike in young healthy persons, in the prevention of disease the therapeutic range of physical activity may be narrow among individuals with chronic disease. In exercise therapy long-term adherence is a general problem. In clinical work we have to take into account that correction of other modifiable risk factors such as diet and smoking are also important, as is the optimal medication.

Additional reading

Kujala UM. Evidence for exercise therapy in the treatment of chronic disease based on at least three randomized controlled trials – summary of published systematic reviews. Scand J Med Sci Sports 2004;14:339-345.

Taylor RS, Brown A, Ebrahim S, et al. Exercise-based rehabilitation for patients with coronary heart disease: systematic review and meta-analysis of randomized controlled trials. Am J Med 2004;116:682-692.

Smart N, Marwick TH. Exercise training for patients with heart failure: a systematic review of factors that improve mortality and morbidity. Am J Med 2004; 116: 693-706.

Thomas DE, Elliot EJ, Naughton GA. Exercise for type 2 diabetes mellitus. Database of Cochrane Systematic Review, 2007.

Abstract

The athletes' heart: from physiology to pathology

Physical training results in adaptations of the cardiovascular system characterised by cardiac enlargement in the presence of normal or improved function leading to additional heart sounds on auscultation and concomitant to electrical conduction changes observed on ECG. The nature and degree of adaptation is dependent upon the type of sports training and is believed to be a physiologic process leading to and enhanced cardiovascular function that is reversible following cessation of training. Exercise per se leads to a 10-fold increase in cardiovascular events in those with underlying disease associated with the significant stress placed upon the heart during physical activity. Tragically, adverse cardiac events and sudden death are evident in highly trained athletes that are most commonly associated with inherited cardiac disease. Recent evidence suggests a transient depression of cardiac function and the presence of blood markers of cardiac damage. Whilst it is believed that this phenomenon is physiologic in nature the implications of life-long participation in endurance exercise are less well understood. An increased prevalence of complex brady- and tachy-arrhythmias in veteran athletes together with recent evidence for myocardial fibrosis may suggest a non-physiologic alteration of the heart to repeated bouts of arduous endurance exercise. This presentation will present the evidence for physiologic adaptations of the cardiovascular system in response to training and examine the limited data examining the implications of life-long competitive exercise.

Abstract

Cardiac risk and benefits in swimmers

As physical inactivity is increasingly recognised as a major cardiovascular risk factor the benefits of exercise are well established Weight reduction, improved glucose tolerance and lipid profiles, improved skeletal muscle performance and associated psychological benefits have stimulated the application of exercise prescription in many disease states initially being applied to cardiac disorders. The form, intensity and duration of exercise remain a subject of debate and may greatly influence patient compliance with an exercise programme.

The popularity of swimming makes it an attractive activity as part of a lifestyle package either as a primary or secondary intervention. Several aspects of the physical demands of swimming may provide specific cardiovascular challenges to patients with cardiac disease with major changes associated with emersion particularly in a cold environment. This may stimulate increased sympathetic activity with resulting demands on myocardial function, which may cause problems in patients with coronary artery disease and hypertension. Additional effects may be induced with vagal over activity associated with the diving reflex with bradycardia, reduced cardiac output and intense peripheral vasoconstriction. Immersion at any temperature may be associated with brief but potentially serious episodes of both atrial and ventricular arrhythmias.

Exercise is a risk to a small number of athletic participants. Sudden death may occur in subjects with predisposing cardiac conditions, which have been shown in studies to be secondary to structural abnormalities in the young, arrhythmic problems, which may have a hereditary basis and coronary artery disease in those over the age of 30 years. The conditions predisposing to sudden death do not appear to be sport specific and the challenge of prevention of these rare events faces all National and International Governing Bodies. Preparticipation screening programmes have been advocated but their application has been limited by factors of practicality and cost. Some programmes however have been successful in reducing the mortality during exercise in subjects with heart muscle disease and these results challenge us all to put appropriate programmes in place.