Evidence for prescribing exercise as therapy in chronic disease

Considerable knowledge has accumulated in recent decades concerning the significance of physical activity in the treatment of a number of diseases, including diseases that do not primarily manifest as disorders of the locomotive apparatus. In this review we present the evidence for prescribing exercise therapy in the treatment of metabolic syndrome-related disorders (insulin resistance, type 2 diabetes, dyslipidemia, hypertension, obesity), heart and pulmonary diseases (chronic obstructive pulmonary disease, coronary heart disease, chronic heart failure, intermittent claudication), muscle, bone and joint diseases (osteoarthritis, rheumatoid arthritis, osteoporosis, fibromyalgia, chronic fatigue syndrome) and cancer, depression, asthma and type 1 diabetes. For each disease, we review the effect of exercise therapy on disease pathogenesis, on symptoms specific to the diagnosis, on physical fitness or strength and on quality of life. The possible mechanisms of action are briefly examined and the principles for prescribing exercise therapy are discussed, focusing on the type and amount of exercise and possible contraindications.     

Evidence for exercise therapy in the treatment of chronic disease based on at least three randomized controlled trials--summary of published systematic reviews

Final evidence for the overall benefits of exercise therapy in the treatment/rehabilitation of specific chronic disease comes from randomized controlled trials (RCTs). This paper summarizes current evidence that is based on a systematic review including data from at least three RCTs with contrast for exercise only. The quality of specific RCTs as well as the quality of systematic reviews varies, the newest ones usually being of higher quality than the older ones. The most consistent finding of the studies is that aerobic capacity and muscular strength of patients can be improved without causing detrimental effects on disease progression. Severe complications during these carefully tailored programs were rare. The treatment periods and follow-up times of the majority of the RCTs are of a too short duration to document group differences in disease progression. However, exercise reduces disease-related symptoms in many diseases, such as osteoarthritis, asthma and chronic obstructive pulmonary disorder. Also, RCTs studying patients with coronary heart disease as well as patients with heart failure show that all-cause mortality is lower in exercisers than in controls.     

Considerations in prescribing preflight aerobic exercise for astronauts

Many human responses to the weightless environment have been documented from actual spaceflights. These include physiological effects on the nervous system, cardiovascular system and fluid balance, and the musculoskeletal system, as well as psychological effects. Simulations on Earth have added to our knowledge about the physiology of weightlessness. Early data on orthostatic intolerance after real and simulated spaceflight led some scientists to discourage a high level of aerobic fitness for astronauts. They believed it was detrimental to orthostatic tolerance on return to Earth. However, most of the data available today do not support this contention. Furthermore, aerobic fitness is beneficial to cardiovascular function and mental performance. Therefore, it may be important in performing extra-vehicular activities during flight. Some astronauts claim exercise enhances their feeling of well-being and self image. And, although the cardiovascular system and exercise performance may recover more slowly after flight to preflight levels when fitness level prior to flight is high, the musculoskeletal system may recover more rapidly. Research is needed to determine optimal levels of aerobic training for performing tasks in flight, maintaining health and well-being during flight, and assuring satisfactory recovery on return to Earth.     

Aggressive exercise as treatment for chronic low back pain.

Exercise has long been a standard of treatment for back pain. Over the last 2 decades, the use of intense, non-pain-contingent exercises for treatment of chronic back pain has received increased advocacy. The main goals of these treatments are to improve functioning of painful lumbar soft tissue and to decrease the fears and concerns of patients about using their backs for daily activities. The methodology of an aggressive quota-based exercise approach to back pain is outlined in this article. This approach relies on objective quantification of physical capabilities, treatment directed at altering these parameters, and repeat quantification for determination of treatment efficacy and positive feedback. By eliminating impairments in back function, altering fears and beliefs about pain, and reducing disability, patients with chronic low back pain can achieve meaningful improvements in their quality of life.     

Regular exercise as an effective approach in antihypertensive therapy

PURPOSE: Exercise has been well documented to exert a beneficial effect on cardiovascular health. The effective control of arterial pressure (BP) is essential from the standpoint of cardiovascular prevention. So far, no study has determined the long-term effect of regular training as a monotherapy on both BP at rest and during exercise. METHODS: Therefore, 10 subjects with hypertension (aged 43 +/- 3 yr) were studied in order to define BP response to long-term aerobic training. BP measurements were obtained at rest and during ergometry (50-100 W). Patients were instructed to exercise weekly (2 x 60 min aerobic exercise). RESULTS: BP during exercise (100 W) did fall already after 6 months of regular training from 184 +/- 10/107 +/- 6 to 170 +/- 10/100 +/- 7, and this was associated with a 14% decrease in the rate-pressure product (at 100 W). After 18 months of training, there were further reductions in BP, at rest from 139 +/- 9/96 +/- 6 to 133 +/- 14/91 +/- 7 (P < 0.05) and during ergometry (100 W) from 184 +/- 10/107 +/- 6 to 172 +/- 8/96 +/- 6 mm Hg (P < 0.001). During a 3-yr follow-up, BP continued to decrease significantly to 130 +/- 13/87 +/- 7 mm Hg at rest and 167 +/- 9/92 +/- 6 mm Hg during exercise. No significant changes in body weight were documented during the training period. CONCLUSION: The data demonstrate that long-term aerobic exercise is associated with a decrease in BP at rest and during exercise, which is comparable to that of drug therapies. This antihypertensive effect of regular training can be maintained as long as 3 yr.     

Assessing the efficacy of exercise training in patients with chronic disease

PURPOSE: The purpose of this study was to evaluate the meaningfulness of exercise training responses in patients with end stage renal disease (ESRD). METHODS: Eighteen ESRD patients [(mean +/- SD); 54.3 +/- 17.1 yr] completed a training regime progressing to accumulate 40 min of stationary cycling, three times per week for 6 months. .VO(2peak) determined via incremental cycle ergometer protocol, and .VO(2) kinetics determined from a transition from unloaded pedalling to an exercise intensity corresponding to 90% of VT, were assessed at baseline and at 3 and 6 months of training. RESULTS: Repeated measures analysis of variance revealed significant changes (P < 0.05) on the time factor for .VO(2peak), VO(2)-V(T), and .VO(2) kinetics. Post hoc analysis revealed that .VO(2peak) and .VO(2) kinetics significantly (P < 0.05) improved at 3 months of training with no further improvements thereafter. Analysis of individual subject response data revealed that after 3 months of training, 61% of the patients improved .VO(2peak) by greater than the standard error of measurement (SEM = 0.07 L.min(-1)). At 6 months of training, approximately 89% of the patients improved by more than the SEM .VO(2) kinetics improved by more than the SEM (12.3 s) at 3 months of training in approximately 55% of the patients, with no increase in the number of patients exhibiting faster time constants after 6 months of training. CONCLUSION: Although conventional statistical analyses indicate that exercise training favorably alters .VO(2peak) and oxygen uptake kinetics of patients with ESRD, it is apparent that considerable interindividual variability exists in the response to training. Consideration of the SEM data underscores the heterogeneity of adaptive response in this patient group and may be valuable in assessing the efficacy of therapeutic exercise rehabilitation.     

Safety of chronic exercise in a rat model of kidney disease

PURPOSE: The objective of this study was to determine the effect of treadmill running on polycystic kidney disease (PKD) progression and bone mineral density in Han:SPRD-cy rats, an animal model of PKD. METHODS: Using a 2 x 2 design, normal and polycystic male rats were divided randomly into exercise and sedentary groups at 4 wk of age. The exercising group performed treadmill exercise (14 m x min(-1)) for 30 min 3 d x wk(-1) for 6 wk, whereas the control group remained sedentary. This 6-wk period represents the period of greatest cyst growth in this model. RESULTS: Both exercised and sedentary polycystic animals had significantly greater kidney weights, as well as greater concentrations of serum urea nitrogen and serum creatinine than control animals. Exercise did not alter these parameters in either normal or polycystic animals. In addition, bone mineral density and bone mineral content, determined by dual-energy x-ray absorptiometry, were not altered by exercise in these animals. Bone mineral content, however, was marginally lower in polycystic animals. CONCLUSIONS: These results support the safety of moderate exercise in PKD. Additional research in this area is needed since there may be other benefits that are derived from exercise in this population.     

Aerobic exercise as a therapy option for migraine: a pilot study

Exercise is assumed to have a positive effect on migraine. However, none of the few studies on this topic can prove the expected positive influence of exercise. Therefore, the aim of this pilot study was to develop a training program suitable for migraine patients and to examine its effect on migraine. 16 patients were examined. 8 migraine patients completed a 10-week aerobic running exercise program consisting of 3 workouts per week. The program was developed by sports scientists especially to increase the fitness level. Physical fitness, i.?e., physical working capacity, was assessed using a PWC 150 test. There was also a control group of 8 patients without any special physical training. Migraine patients of the exercise group showed both a reduction in the number of migraine days per month (p=0.048) and the intensity of the attacks (p=0.028). An increase in fitness level resulted in a lowered stress level. Stress strategies like "displacement activity" (r=-0.715; p=0.046), "looking for self-affirmation" (r=-0.742; p=0.035) and "feelings of aggression" (r=-0.802; p=0.017) were reduced. Increasing the level of fitness (PWC 150) is one predictor for migraine improvement (r=0.409, p=0.031). Aerobic exercise which leads to a better fitness level is an alternative therapy method for migraine.     

Evidence for low muscle capillary supply as a pathogenic factor in chronic compartment syndrome

There is a paucity of data regarding the pathogenesis of chronic exertional compartment syndrome (CECS), its consequences for the muscles and the effects of treatment with fasciotomy. We analyzed biopsies from the tibialis anterior muscle, from nine patients, obtained during a decompressing fasciotomy and during follow‐up 1 year later. Control biopsies were obtained from nine normal subjects. Muscle capillarity, fiber‐type composition and fiber area were analyzed with enzyme‐ and immunohistochemistry and morphometry. At baseline, CECS patients had lower capillary density (273 vs 378 capillaries/mm², P=0.008), lower number of capillaries around muscle fibers (4.5 vs 5.7, P=0.004) and lower number of capillaries in relation to the muscle fiber area (1.1 vs 1.5, P=0.01) compared with normal controls. The fiber‐type composition and fiber area did not differ, but focal signs of neuromuscular damage were observed in the CECS samples. At 1‐year follow‐up after fasciotomy, the fiber area and the number of fibers containing developmental myosin heavy chains were increased, but no enhancement of the capillary network was detected. Thus, morphologically, patients with CECS seemed to have reduced microcirculation capacity. Fasciotomy appeared to trigger a regenerative response in the muscle, however, without any increase in the capillary bed.     

Oral magnesium therapy, exercise heart rate, exercise tolerance, and myocardial function in coronary artery disease patients

Background

Previous studies have demonstrated that in patients with coronary artery disease (CAD) upward deflection of the heart rate (HR) performance curve can be observed and that this upward deflection and the degree of the deflection are correlated with a diminished stress dependent left ventricular function. Magnesium supplementation improves endothelial function, exercise tolerance, and exercise induced chest pain in patients with CAD.

Purpose

We studied the effects of oral magnesium therapy on exercise dependent HR as related to exercise tolerance and resting myocardial function in patients with CAD.

Methods

In a double blind controlled trial, 53 male patients with stable CAD were randomised to either oral magnesium 15 mmol twice daily (n = 28, age 61±9 years, height 171±7 cm, body weight 79±10 kg, previous myocardial infarction, n = 7) or placebo (n = 25, age 58±10 years, height 172±6 cm, body weight 79±10 kg, previous myocardial infarction, n = 6) for 6 months. Maximal oxygen uptake (VO_2max), the degree and direction of the deflection of the HR performance curve described as factor k<0 (upward deflection), and the left ventricular ejection fraction (LVEF) were the outcomes measured.

Results

Magnesium therapy for 6 months significantly increased intracellular magnesium levels (32.7±2.5 v 35.6±2.1 mEq/l, p<0.001) compared to placebo (33.1±3.1.9 v 33.8±2.0 mEq/l, NS), VO_2max (28.3±6.2 v 30.6±7.1 ml/kg/min, p<0.001; 29.3±5.4 v 29.6±5.2 ml/kg/min, NS), factor k (−0.298±0.242 v −0.208±0.260, p<0.05; −0.269±0.336 v −0.272±0.335, NS), and LVEF (58±11 v 67±10%, p<0.001; 55±11 v 54±12%, NS).

Conclusion

The present study supports the intake of oral magnesium and its favourable effects on exercise tolerance and left ventricular function during rest and exercise in stable CAD patients.     

Portal venous hemodynamics in chronic liver disease: effects of posture change and exercise

Changes of portal hemodynamics with the progression of chronic liver disease and changes caused by body posture and physical exercise were investigated using an ultrasonic pulsed Doppler flowmeter in healthy adults and in patients with chronic persistent hepatitis, chronic active hepatitis, and cirrhosis. Portal venous velocity was significantly reduced in patients with chronic active hepatitis, cirrhosis without a large splenorenal shunt, and cirrhosis with a large splenorenal shunt, compared with normal subjects and patients with chronic persistent hepatitis. Portal venous flow, by contrast, was significantly reduced only in patients with cirrhosis and a large splenorenal shunt compared with normal subjects and with the other three groups; there was no significant difference in portal venous flow among the latter four groups. Both portal venous velocity and flow showed a tendency toward further reduction in patients with cirrhosis who had hepatofugal flow of part of the superior mesenteric venous blood into the splenic vein and a large splenorenal shunt. Both exercise and posture change from supine to sitting significantly reduced portal venous velocity and portal venous flow in normal subjects, as well as in the patients with chronic liver disease.