Exercise Conditioning and Cardiopulmonary Fitness in Cystic Fibrosis: The Effects of a Three-month Supervised Running Program

doi:10.1378/chest.80.4.392

Chest

Volume 80, Issue 4, October 1981, Pages 392-398

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Exercise intolerance is common in cystic fibrosis (CF). We examined the effects of a supervised three-month running program on exercise tolerance, pulmonary function, cardiorespiratory fitness (peak oxygen consumption), and respiratory muscle endurance in CF patients. We studied 31 patients, 21 exercise and ten control, aged 10 to 30 years, with pulmonary involvement ranging from mild to severe. The exercise and control groups were not significantly different with respect to age, sex, pulmonary function, exercise tolerance, or cardiorespiratory fitness. After three months of physical conditioning, the exercise group had significantly increased exercise tolerance and peak oxygen consumption and significantly lower heart rates for submaximal work loads, while the nonexercising (control) group was unchanged in all these variables. The FEV₁ decreased significantly in the control group. There were no other significant changes in pulmonary function in either the control or exercise group. Respiratory muscle endurance increased significantly in the exercise patients, and did not change in the control patients. There were no adverse effects of the program. The data suggest that a supervised running program can increase CF patients’ exercise tolerance and cardiorespiratory fitness, perhaps in part by increasing respiratory muscle tolerance. The effects of a much longer program deserve study.

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PATIENTS AND METHODS

Thirty-five patients, 17 males and 18 females, aged 10 to 30 years, followed up for two to 22 years in the Cleveland Cystic Fibrosis Center, volunteered for this study. Cystic fibrosis was diagnosed by an abnormal sweat test and either typical pulmonary or digestive symptoms or family history of the disease.⁶ After volunteering, the patients were divided into exercise and control groups, based on proximity to the center: those who lived close enough to be able to attend three sessions each week

Initial Evaluations

There were no significant differences in the standard pulmonary function or exercise capacity between the exercise and control groups on entry into the study.

Exercise Testing (Fig 1): The 31 CF patients had widely differing exercise tolerances on entry into the study, with peak $\dot{V}$ _O₂ ranging from 10.6 to 53.9 ml/kg/min, compared with the 40 to 50 ml/kg/min expected for normal persons of similar ages.¹⁴ The mean peak $\dot{V}$ _O₂ was 33.6 ± 9.1 ml/kg/min. Maximum heart rates ranged from 133 to 210 beats

Evaluations After Exercise Conditioning

Exercise Tolerance (Fig 3): After three months of physical conditioning, the exercise group had significantly improved exercise tolerance (peak work capacity) (P < .005) and peak oxygen consumptions (P < .005). Thirteen of 21 patients were able to pedal at least one additional minute in the progressive test. One additional patient achieved the same workload, but because she also lost weight, her ${\dot{V}}_{O_{2}}$ in ml/kg/min was increased. Six patients had unchanged exercise tolerance and oxygen

DISCUSSION

Our evaluations before exercise conditioning confirmed Godfrey and Mearns’ findings in CF patients.¹ There was wide variability in exercise tolerance of CF patients, with most showing some degree of limitation, worsening as disease severity increased, poorly predicted by standard pulmonary function tests in the individual, but for the population correlating with degree of pulmonary obstruction. Furthermore, we examined peak ${\dot{V}}_{O_{2}}$ , a good correlate of overall cardiorespiratory fitness.¹⁴ Peak

ACKNOWLEDGMENT

The authors gratefully acknowledge the expert assistance of Anthony E. Bacevice, Jr., M.S., who designed the computerized exercise lab, and the superb technical assistance or Fred Montague, M.S.

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The aim of this position statement was to inform the choice of physical activity tools for use within CF research and clinical settings.
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Our current position is that activity monitors such as SenseWear or ActiGraph offer informed choices to facilitate a comprehensive assessment of physical activity, and should as a minimum report on dimensions of physical activity including energy expenditure, step count and time spent in different intensities and sedentary time. The DigiWalker pedometer offers an informed choice of a comparatively inexpensive method of obtaining some measurement of physical activity. The HAES represents an informed choice of questionnaire to assess physical activity. There is insufficient data to recommend the use of one diary over another. Future research should focus on providing additional evidence of clinimetric properties of these and new physical activity assessment tools, as well as further exploring the added value of physical activity assessment in CF.
Moderate intensity exercise mediates comparable increases in exhaled chloride as albuterol in individuals with cystic fibrosis
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Citation Excerpt :
Ameliorating this ion dysregulation is crucial in the treatment of CF. Although the majority of current therapies treat the ensuing symptoms, the ultimate goal in the treatment of CF and the focus of current research is to treat the basic pathophysiology due to CFTR dysfunction. The systemic therapeutic benefits of exercise in CF are well known, demonstrating the ability to reduce the characteristic 2–3% annual decline in pulmonary function, increase respiratory muscle endurance, improve exercise tolerance, aid in facilitating sputum clearance, increase aerobic capacity, and result in improved survival for individuals with CF who have higher aerobic fitness [5–10]. More recently, the benefits of exercise have been extended to a more cellular level with demonstration of inhibition of ENaC activity with exercise, thereby potentially improving ion regulation.
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: Supported in part by NIH grant AM 08305, HL 07415, The Cystic Fibrosis Foundation, United Way Services of Cleveland, and USDHEW, NIH Rehabilitation Services Administration grant 13-P55917.

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