middle age or beyond may be as important as those initiated at younger ages.
Randomised clinical trial data are available for the prevention of some diseases with exercise (e.g., secondary cardiovascular events, diabetes mellitus, and osteoporotic fracture) but are not yet available for others (stroke, dementia, depression). Diabetes is clearly preventable in high‐risk obese adults with impaired glucose tolerance randomised to exercise and diet, as shown in the Finnish Diabetes Study82 and the Diabetes Prevention Program (DPP), among others.149 Similarly to Finnish subjects, DPP participants randomly assigned to the intensive lifestyle intervention of diet and exercise reduced their risk of incident type 2 diabetes by 58% by 3 years compared to control (lifestyle advice only), and significantly better than metformin prescription. Of particular interest is the finding that those over the age of 60 responded best, with a 71% reduction in incident diabetes in this time frame, while metformin was no better than the control condition in this older age group.
The major diseases and syndromes for which exercise may be beneficial as a preventive strategy are listed in Table 7.6, along with the postulated mechanisms of exercise benefit and the specific modality of exercise most relevant for these outcomes.
Table 7.6 Potential mechanisms by which exercise can prevent disease.
| Disease or syndrome | Postulated mechanisms of exercise effect | Recommended exercise modality |
|---|---|---|
| Arthritis | Decreased body weightMaintenance of cartilage integrityMaintenance of muscle and tendon strength | Aerobic exercise Resistance exercisea |
| Cancer (breast, colon, prostate) | Decreased body fatDecreased oestrogen levelsAltered dietary intakeDecrease in gastrointestinal transit timeIncreased prostaglandin F2 | Aerobic exercise Resistance exercisea |
| Chronic renal failure | Reduced risk of hypertensionReduced risk of type 2 diabetes mellitus | Aerobic exercise Resistance exercisea |
| Congestive heart failure | Decreased risk of ischaemic heart diseaseDecreased risk of hypertensionDecreased risk of type 2 diabetes mellitus | Aerobic exercisea Resistance exercisea |
| Coronary artery disease | Decreased blood pressureDecreased LDL cholesterolIncreased HDL cholesterolDecreased fibrinogenDecreased total body fat, visceral fatDecreased insulin resistance, hyperinsulinaemiaDecreased cortisol levels, inflammatory cytokinesIncreased adherence to smoking cessation, dietary behavioursDecreased depression, anxietyImproved endothelial cell function | Aerobic exercise Resistance exercise |
| Dementia | Improved cerebral blood flowIncreased neurotrophic factors in CNSHippocampal neurogenesisAnabolic hormones | Aerobic exercisea Resistance exercisea |
| Depression | Increased self‐efficacy, masteryInternalised locus of controlDecreased anxietyImproved sleepIncreased self‐esteemIncreased social engagement, decreased isolationDecreased need for drugs associated with depression (beta blockers, alpha blockers, sedative hypnotics)Decreased body fat, improved body image | Aerobic exercise Resistance exercisea |
| Osteoporotic fracture | Increased bone densityIncreased tensile strengthIncreased muscle massImproved gait stability and balanceImproved nutritional intake (energy, protein, calcium, vitamin D)Reduced fear of falling, improved self‐efficacyIncreased overall activity levels, mobilityDecreased need for drugs associated with postural hypotension, falls, hip fractures (antidepressants, antihypertensives, sedative‐hypnotics) | Resistance exercise Balance exercise |
| Stroke | Decreased obesityDecreased blood pressureDecreased cholesterol | Aerobic exercise Resistance exercisea |
| Type 2 diabetes mellitus | Improved insulin sensitivityIncreased GLUT‐4 protein and translocation to membrane sitesReduced visceral fat massDecreased cortisol response to stressImproved dyslipidaemiaDecreased blood pressureIncreased muscle mass | Aerobic exercise Resistance exercise (combined with diet and aerobic exercise) |
a Indicates that the modality of exercise has been shown to affect the postulated mechanistic factors but has not yet been shown to prevent the distal disease outcome in epidemiological/clinical studies.
Evidence for the role of exercise in the treatment of disease
Mechanisms of benefit
There are many ways to conceptualise the integration of exercise into the treatment of established disease. For example, traditional medical interventions do not typically address disuse syndromes accompanying chronic disease, which may be responsible for much of their associated disability. Exercise is particularly good at targeting syndromes of disuse and may thus significantly impact disability without altering the underlying disease itself in any primary way. Examples include Parkinson’s disease, chronic obstructive pulmonary disease, and chronic renal failure. Exercise may also lower the risk of recurrence of a disease, such as secondary events in patients with cardiovascular disease or preventing recurrent injurious falls in an individual after a hip fracture. Some pathophysiological aberrations central to a disease are specifically addressed by exercise, which may therefore serve as an adjunct to standard care. For example, losses of visceral fat achieved through resistive or aerobic training improve insulin resistance and complement dietary and pharmacological management of type 2 diabetes in the older adult with central obesity.22
Exercises designed to stimulate skeletal muscle hypertrophy in congestive heart failure provide benefits that counteract the catabolic effects of circulating cytokines in this disease and are not achievable with cardiac medications alone. Indeed, regular exercise induces antiatherogenic adaptations in vascular function and structure, irrespective of traditional cardiovascular disease (CVD) risk factors. Muscle‐derived myokines are responsible for many of the beneficial effects of exercise, particularly by promoting a healthy anti‐inflammatory milieu.21
Functional improvements in individuals with arthritis who are given lower‐extremity exercises include improved joint stability and may thus add to the benefits of anti‐inflammatory and analgesic medications. It is not possible in this chapter to review every disease in which exercise has beneficial effects, and therefore we will use type 2 diabetes as one example of the diseases outlined in Table 7.7.
Exercise in the treatment of type 2 diabetes
The prevalence of type 2 diabetes appears to be rising precipitously, linked to the rise in obesity throughout the world. Most of the individuals concerned have scope for lifestyle modification, particularly for suboptimal levels of physical activity. Cardiovascular disease accounts for half of the mortality in older adults with type 2 diabetes,150 emphasising the complex clinical syndrome represented by this cohort.
The
