Knowledge of the cardiovascular and pulmonary consequences of conditions other than those of the cardiovascular and pulmonary systems enables the physical therapist to assess oxygen transport status, limitations, and risk factors in these individuals, in addition to ensuring their safety when undergoing physical activity and exercise. Such knowledge enables the physical therapist to prescribe exercise to optimize oxygen transport, maximize functional capacity and life participation, and maintain optimal long-term health.

Individuals with Musculoskeletal Conditions

Exercise is prescribed for a broad range of conditions affecting the musculoskeletal system, with favorable outcomes and no documented deleterious effects. With increased understanding of exercise pathophysiology, physical therapists can prescribe therapeutic exercise that has the greatest benefit in terms of improved activities of daily living and life satisfaction with the least risk. Individuals with mitochondrial myopathies and nonmetabolic myopathies experience typical aerobic responses to low intensity training (i.e., improved aerobic capacity and reduced submaximal heart rate and blood lactate).⁴ The extent of these training effects, however, is less in individuals with nonmetabolic myopathies compared with those who have mitochondrial myopathies. Improved aerobic capacity is associated with improved self-reported functional status and quality of life in both groups.

Because the pathoetiology of stroke involves atherosclerosis and hypertension, individuals with stroke need to be managed comparably to individuals with systemic atherosclerosis and circulatory dysfunction. Appropriate precautions must be taken when exercising these individuals or conducting other physical therapy interventions. Within weeks after a stroke, cardiorespiratory deconditioning complicates the clinical picture, along with muscle weakness, spasticity, incoordination, and abnormal gait.¹³ In the subacute stage of stroke, individuals who undergo aerobic training can improve aerobic and functional abilities;¹⁴ however, these benefits may not be reflected in the long-term by indexes such as the Frenchay Activities Index.^15,16 Although research is necessary to refine exercise testing and training procedures for individuals with stroke,¹⁷ there is no reason to believe that these patients would not respond to aerobic conditioning to counter the deconditioning that occurs after stroke or that this intervention would not augment gait reeducation and sensorimotor integration. Evidence supports that the application of a modified treadmill training protocol, based on exercise physiology principles, can be superior to conventional approaches to the rehabilitation of people with strokes.¹⁸

Although individuals with physical impairment secondary to stroke present methodological challenges during exercise testing and training, submaximal oxygen consumption () has good agreement with maximum () when the test is tightly standardized.¹⁹ The high degree of reliability of these tests supports their use as outcome measures in this population. Metabolic assessment during short, submaximal tests, such as a five-minute walk, can provide supplemental information for evaluating gait in individuals with stroke.²⁰ Individuals with mild-to-moderate impairment from chronic stroke who require hand rail support on the treadmill also have been reported to have good reliability with respect to heart rate and oxygen pulse in peak-effort treadmill testing.²¹ However, hand rail support is an important variable that can increase or decrease work intensity and thus must be described and recorded to facilitate comparison of exercise results across tests. Hand rail support can be described on the data sheet with respect to side or front support, one or two hands, finger support or grasp support, and heavy or light support.

Treadmill training has proven to be a useful means of improving fitness and offsetting deconditioning in individuals with stroke. Individuals with impaired gait can improve their oxygen transport reserve capacity with a regular program of treadmill walking.²² Peak and walking workload are increased, and the energy cost associated with abnormal gait is reduced. For individuals with stroke, these changes may help to enhance functional capacity comparable to those achieved in individuals with other neurological deficits.

Treadmill training and weight support with a body harness for walking after stroke are showing promise in terms of conditioning strategy and gait reeducation.²³ Patients with severe impairments after stroke who retrain their gait with a portion of their body weight (up to 40%) supported during exercise have better outcomes after training than those who carry their full weight.²⁴ Older individuals and those with the most impairment show the greatest benefits. These individuals walk more symmetrically on a treadmill compared with ground walking, and they walk with less spasticity and improved movement economy.²⁵ Furthermore, improvement in treadmill walking speed in these individuals generalizes to balance, trunk control, functional activities, and ground locomotion.^24,26 Training at speeds comparable to an individual’s normal velocity over ground is more effective than training at speeds above or below that velocity.²⁷ Also, when different treadmill walking protocols are compared, structured speed-dependent treadmill training, as performed in sports training, improves walking ability more than either modified progressive treadmill training or conventional gait training.¹⁸

Despite the compelling results of studies on partial body weight support in the rehabilitation of individuals with stroke, these and related studies often fail to address the principles of physical therapy for management of individuals with systemic atherosclerosis, which include hemodynamic monitoring and possibly electrocardiogram (ECG) screening. One exception was a study by Eng et al (2002)²⁸ that recommended that actual exertion (defined as a physiology measure; specifically, rate pressure product or heart rate) be measured in conjunction with walking distance in functional walk tests when testing people with stroke. When performance on several functional walk tests was compared, performance was associated with level of impairment rather than perceived exertion or intensity as measured by rate pressure product or heart rate. Thus debility may limit aerobic training capacity.

Aerobic exercise may have a preventive effect for stroke mediated by endothelium-dependent vasodilation in the cerebral arterioles.²⁹ Several risk factors are associated with impairment of this mechanism. Exercise stimulates the expression of endothelial nitric oxide synthase, which promotes vascular dilation and thereby exercise’s potential protective and preventive effect.

Community ambulation is a meaningful outcome for people with stroke.³⁰ A discrepancy exists, however, between mobility outcomes on standardized measures of community-based individuals and the extent to which they actually get out in the community. Gait velocity is an important variable in determining community ambulation capacity.

Resistance muscle training has been of interest as a component of physical therapy management of individuals with stroke. Strength training augments the benefits of aerobic exercise with respect to functional strength³¹ without reinforcing abnormal movement patterns.³² One study, however, reported no difference between leg exercise training programs with and without resistance.³³ Inadequate exercise prescription to explain the absence of an effect of resistance training cannot be ruled out.

When prescribing exercise for individuals with stroke, it must be remembered that stroke results from a hemodynamic insult—usually high blood pressure. Aerobic exercise and resistance muscle training elicit unique hemodynamic responses; thus the hemodynamic status of individuals with stroke must be assessed in the initial baseline review, considered carefully in the exercise prescription, and assessed in the outcomes of these programs. If blood pressure is being pharmacologically managed, then an objective of exercise will be to augment oxygen transport efficiency and normalize blood pressure. Medications must be followed so that these can be reduced or withdrawn in response to an overall effect of a comprehensive exercise and management program.

Individuals with Connective Tissue Conditions

The exercise limitations of individuals with connective tissue conditions result in part from the restrictive component of lung dysfunction associated with these conditions. These individuals may have normal chest x-ray and conventional pulmonary function yet have histochemical abnormalities of their lungs (e.g., shrinking lung associated with scleroderma).

Resting data are limited in predicting responses to activities of daily living and exercise. Thus exercise testing is a primary tool to assess pulmonary function dynamically and thereby unmask abnormalities that can compromise daily function.⁵³ Women with systemic lupus erythematosus (SLE) have a several-fold increase in incidence of heart disease over other women, corresponding to an increased number of cardiac risk factors.⁵⁴ In addition, hypertension and diabetes are also more prevalent in this group.

Individuals with Rheumatoid Conditions

Individuals with rheumatoid arthritis (RA) have a higher incidence of cardiovascular disease and related mortality. Despite normal left ventricular systolic function, left ventricular diastolic function is impaired without clinical evidence of cardiovascular disease, which may place this group at risk.⁵⁵ At maximal exercise, heart rate, systolic blood pressure, and peak are comparable for individuals with RA and healthy people.

Contemporary approaches to the management of people with RA include exercise prescription for strength, endurance, and emotional well-being.⁵⁶ Joint inflammation may be reduced with judiciously prescribed exercise.

Individuals with Gastrointestinal Conditions

Conditions such as irritable bowel syndrome and Crohn’s disease are characterized by disturbed homeostasis related to gut motility and function. Because these conditions are chronic and medical care is noncurative, physical deconditioning and debility are common. Few studies have examined the acute or chronic effects of exercise in this population, so specific guidelines for testing and training are lacking. One study examined the effects of moderately intense exercise (60% of for 1 hour) on gastrointestinal function in individuals with Crohn’s disease who were in remission.⁵⁷ The conventional measures of gastrointestinal function were unchanged. It may be necessary to observe caution because of oxygen metabolite production and potential zinc deficiency. Individuals with gastrointestinal conditions have nutritional deficits that must be considered when placing increased metabolic demands on energy substrate stores. The capacity of these individuals to respond to exercise appropriately will fluctuate with exacerbations and remissions of their conditions. It is hoped that with improved health and functional capacity, the duration between exacerbations will be increased, the severity of exacerbations will be reduced, and speed of recovery will be increased.

Individuals with Hepatic Conditions

The exercise responses of individuals with hepatopulmonary syndrome (HPS) are not well understood, which has hampered attempts to define guidelines for mobilization and exercise testing and training. One study, however, has shown that individuals with HPS have markedly reduced aerobic capacity and exercise-induced hypoxemia that exceeds the limitations of patients with liver disease but without the syndrome.⁵⁸ Hypoxemia and increased ventilatory dead space at peak exercise support impairment in the pulmonary circulation.

Exercise capacity and maximum oxygen consumption are impaired by cirrhosis. This can be explained by an associated cirrhotic cardiomyopathy. Myocardial thickening and ventricular stiffness lead to decreased diastolic function and inotropic and chronotropic incompetence when the oxygen transport system is stressed during exercise.⁵⁹

Individuals with Renal Conditions

Limitation of mitochondrial oxidative capacity has been ruled out as a limiter of exercise capacity in patients with chronic renal failure.⁶⁰ Muscle oxygen conductance, however, is low.

Exercise has a role in the management of individuals undergoing hemodialysis. One study examined the role that normalizing hemoglobin has on exercise response of these individuals.⁶¹ Although both young and old subjects showed evidence of improved oxygen transport and exercise tolerance, exercise responses were not normalized completely. Further, impaired potassium regulation appeared related to hemoglobin concentration and was thought to contribute to exercise limitation.

Patients with end-stage renal disease can also benefit from exercise. Minimally, deconditioning may be prevented, but alternatively, functional status will be improved. An ideal exercise program should have both aerobic exercise and resistance muscle training components, and the prescription for both should be designed to minimize cardiovascular and musculoskeletal risks. Exercise is initiated at a low level to ensure the exercise responses are normal and the patient responds favorably before progression of the prescription. With respect to exercising patients who are severely ill, the consequences of not exercising must be considered.⁶² Regular physical activity, particularly when the patient is relatively stable and well, must be encouraged. This ensures that the patient is as well as possible when a change in his or her condition occurs, which in turn speeds recovery and minimizes associated challenges to aerobic and strength status.

Erythropoietin therapy in the management of patients with chronic renal failure fails to augment peak as much as might be predicted from a corresponding increase in hemoglobin.⁶³ Lactate differences may explain abnormal muscle oxygen transport and reduced exercise tolerance in these patients. Erythropoietin-mediated increases in hemoglobin, however, reduce the respiratory exchange ratio at submaximal exercise (comparable to activities of daily living), reflecting a decrease in anaerobic metabolism and reduced exercise stress.⁶⁴

Chronic renal insufficiency is strongly associated with exercise-induced ischemia in individuals with atherosclerosis. The greater the severity of atherosclerosis in these individuals with chronic renal insufficiency, the greater their cardiovascular risk.⁶⁵

Frequent exercise for patients with renal disease has been proposed as a means of maximizing effective use of their anemia-imposed reduced oxygen delivery capacity.⁶⁶

Individuals with Hematological Conditions

Sickle cell anemia is a common hematological condition in the United States with a high prevalence in the African American population. Patients with sickle cell disease have reduced hemoglobin and oxygen transport capacity. On maximal exercise testing and endurance testing, they have lower exercise tolerance; however, their responses relative to deconditioned individuals without sickle cell anemia are generally comparable.⁶⁷ Thus exercise performance of these individuals must be interpreted in this context.

Individuals with Endocrine Conditions

Individuals with diabetes warrant special consideration with respect to exercise testing and training. Exercise imposes demands on energy substrates and their utilization. Blood glucose abnormalities associated with diabetes necessitate monitoring blood glucose fluctuations before, during, and after exercise. The physical therapist must ensure that the individual eats appropriate foods and at appropriate times in relation to physical activity and exercise. Obesity management is fundamental to the goals of an exercise program as well as normalizing blood glucose metabolism.

Autonomic neuropathies, myopathies, and angiopathies contribute to abnormal exercise responses. Acute exercise responses (e.g., heart rate and blood pressure) may be blunted, as may subjective response to exercise. People with diabetes have a higher incidence of silent ischemia. Heart rate and blood pressure may be less valid indexes of workload. Peripheral vascular disease may result from the direct effect of diabetes, as well as vascular occlusive disease, which is accelerated in individuals with diabetes compared with those who do not have this condition. Altered glucose transfer may also interfere with normal exercise responses. Weight control and nutrition are important to optimize training responses. The capacity to exhibit an optimal training response depends on disease severity, management of the disease, and complications (HbA_1c provides an index of potential complications). Limb perfusion and skin perfusion are monitored before and after exercise. Well fitting, smooth, clean socks must be worn at all times.

Special considerations include monitoring blood glucose before, during, and after exercise (immediate and delayed), at least initially when prescribing exercise for a person with diabetes. Exercise is postponed if blood glucose is extremely high and in the presence of ketone bodies. Daily regular exercise is recommended to maintain health and optimal blood glucose regulation. Intensity should be mild to moderate for a given individual.⁶⁸ Exercise is judiciously timed with the intake of both foods of optimal glycemic index for the person’s needs and insulin or oral agents, as indicated. With improved glucose tolerance and insulin sensitivity and a long-term aerobic exercise program, the need for insulin or oral agents will be affected. The need for these will be eliminated, ideally, or at least reduced.

Individuals with thyroid disease warrant close monitoring. Those who are hypothyroid will be more easily fatigued. Their medical management requires close monitoring to ensure that their condition is normalized as much as possible. If it is, these individuals should have generally normal exercise responses. Those with hyperthyroidism will have high resting heart rates and blood pressure and exaggerated exercise responses.

Individuals with Immunodeficiency Conditions

The pharmaceutical drugs that have been developed to improve the survival of individuals with human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS) (e.g., highly active antiretroviral therapy [HAART]) can impair oxygen transport, hence reducing functional capacity. At peak exercise, heart rate has been reported to be lower and stroke volume higher in individuals with HIV taking HAART when compared with individuals with HIV not taking the drug.⁶⁹ The a-vO₂ difference was lower at peak exercise for those on the drug. HAART is a primary contributor to decreased muscle oxygen extraction-utilization in individuals infected with HIV. The physical therapist must be highly knowledgeable about the combined response of exercise and the potent medications used to control the disease in these individuals. This is important in order to build on an individual’s exercise reserve capacity when health is best, as well as to maintain health and social participation. It is hoped that with improved health and conditioning, morbidity and its severity are reduced.

Immunodeficiency has been implicated in chronic fatigue syndrome (CFS). This syndrome, currently of unknown etiology, appears to run its course over time. Guidelines for exercise testing, particularly maximal testing and training, have been uncertain. In one study individuals with CFS were exercise-tested to the maximal extent. Exercise responses were comparable to individuals with reduced conditioning without CFS, supporting the theory that the physiological responses of individuals with CFS were not abnormal and that exercise testing resulted in no harmful or deleterious effects.⁷⁰

Individuals with Cancer

The physical capacity of cancer survivors and their capacity to respond to exercise conditioning vary depending on the primary type of cancer, the presence of metastases, chemotherapy and radiation therapy and their schedule of administration, and other morbidity.⁷¹ Mind-body considerations, including the psychological, cognitive, and physiological (immune) interface of the patient’s presentation and related outcomes, are emphasized. Given that cancer is a leading cause of morbidity and premature mortality and that many cancer survivors can expect to die with the condition rather than from it as a result of advances in cancer management, the role of exercise has been a focus of attention over the past decade or so. The goals have been to improve health and conditioning, potentially augment remission and reduce progression through immunity stimulation, and reduce the negative effects of the potent treatments that are often administered. Muscle weakness and fatigue are primary complaints of patients with cancer. These complaints are likely related to the body’s attempt to heal itself and in response to the potent treatments, as well as the overall deconditioning associated with illness.^72,73

General guidelines for exercise testing and prescription include resistance training in conjunction with aerobic exercise.⁷¹ Exercise provides both psychological and physical benefits in enabling an individual to thrive when living with cancer. The parameters of the exercise program may vary depending on a patient’s response to potent radiation and chemotherapy (i.e., reducing the intensity and frequency or temporarily discontinuing the program). The role of exercise in improving the health and well-being of people with cancer and in attenuating the negative effects of potent treatments has been a hotbed of research in recent years. Significant advances can be expected in refining exercise testing and training parameters in the near future.

In preparation for exercise prescription, the individual who is obese requires a comprehensive multisystem assessment to establish all factors that may limit exercise tolerance. These individuals require high volumes of physical activity and exercise (see the physical activity and exercise pyramid in Chapter 1) in conjunction with a nutritious dietary program. Introducing more exercise, however, must be done gradually so that it is as enjoyable as possible and also less likely to cause musculoskeletal strain and injury. Biomechanics change with weight loss, and exercise becomes biomechanically less stressful and better tolerated.

Prescriptive parameters for optimal weight loss remain a matter of debate with respect to prolonged, low-intensity aerobic exercise versus short, high-intensity exercise. Moderate intensities of effort, however, have been reported to be more effective at mobilizing fat, whereas heavy exercise promotes energy expenditure after exercise.² The critical factor is the number of calories expended, and burning calories is best achieved with a regularly active lifestyle supplemented with additional formal exercise sessions. Lower-intensity exercise may be favored to avoid musculoskeletal strain or for psychological and motivational reasons. Aerobic training increases lipid oxidation during exercise in fasting conditions.⁷⁴ Such a regimen maintains glucose homeostasis and facilitates fat oxidation. Additional benefits of endurance training for individuals who are obese include reduced cholesterol and insulin concentrations in the blood.

Some individuals may benefit from a structured program (see Chapter 32) and the social support of others in the program.

Summary

This chapter extends the general exercise testing and training principles covered in Chapter 19 and describes special considerations for exercise testing and training individuals with cardiovascular and pulmonary dysfunction secondary to conditions other than primary chronic heart and lung disease. Exercise testing and training is one component of a comprehensive physical therapy management program that is described in Chapter 32.

Conditions that can lead to secondary cardiovascular and pulmonary dysfunction include dysfunction of the musculoskeletal, connective tissue, neurological, gastrointestinal, hepatic, renal, hematological, endocrine, and immunological systems, or some combination thereof. Nutritional disorders, specifically obesity and starvation (anorexia nervosa), also have cardiovascular and pulmonary manifestations. Exercise has a primary role in the management of these conditions, along with the elements of a comprehensive multidisciplinary prevention and rehabilitation program. Knowledge of the potential cardiovascular and pulmonary consequences of conditions other than primary cardiovascular and pulmonary disease is essential to prescribe mobilization and exercise safely and therapeutically for individuals with these conditions to maintain their health and well-being (capacity for activity and participation in life with least physiological risk). Individuals with these conditions are often managed by physical therapists. Thus the cardiovascular and pulmonary manifestations must be considered with respect to physical activity recommendations and the prescription of optimal and safe exercise programs.

Individuals with the potential for cardiovascular and pulmonary dysfunction secondary to noncardiovascular and pulmonary conditions are at significant health risk. Even minor illnesses can have a major impact on their functional capacity. Further, many of these conditions have a progressive degenerative component. This, coupled with aging, can result in what may seem to be a sudden functional decline. Thus oxygen transport of these individuals can benefit from the general health benefits of a lifelong program that includes an exercise program modified based on changes in their condition. Finally, individuals with chronic, secondary cardiovascular and pulmonary conditions likely have underlying risk factors for primary cardiovascular and pulmonary conditions comparable to the general population, if not to a greater extent. Thus both types of pathoetiology must be considered when evaluating limitations in life participation and related activities and their remediation, as well as when evaluating preventive measures for lifelong health and well-being.