Exercise as it relates to Disease/Home-based exercise programs in Cystic Fibrosis: are they sustainable?

This resource is a critique of the article titled; Individualised unsupervised exercise training in adults with cystic fibrosis: a 1 year randomised controlled trial. Moorcroft, AJ, ME Dodd, J Morris, and AK Webb. Thorax 59, no. 12 (2004).

What is the background to this research?
Cystic Fibrosis is a chronic disease which primarily affects the lungs and digestive system. A malfunction of the exocrine glands causes an abnormal amount of thick and sticky mucus to build up within the lungs, airways and digestive system. This excessive build up of mucus traps bacteria in the lungs, which makes Cystic Fibrosis patients susceptible to recurrent infections. Over time this leads to progressive lung dysfunction and damage. Problems Cystic Fibrosis patients present with include:
 * Persistent coughing that produces thick mucus (sputum)
 * Breathlessness
 * Suppressed appetite
 * Repeated lung infections
 * Decreased exercise tolerance

An increasing number of patients with Cystic Fibrosis are surviving into adulthood; this is due to increasingly specialised care, and more effective methods of treatment. Daily treatment includes chest physiotherapy, medication for the respiratory system, oral pancreatic enzymes, vitamin supplements to decrease malabsorption, and exercise.

Exercise training has been studied as a means of improving disease severity for those with Cystic Fibrosis. Several studies have observed a broad range of improvements, such as increased sputum expectoration, and increased ability to perform daily activities. One study performed a 3 year randomised control trial involving supervised exercise training in children with Cystic Fibrosis. They observed a slower annual decline in pulmonary function in those participants who exercised, compared with those who did not exercise. If long term exercise is found to preserve lung function and thus increase survival rates, then long term exercise programs need to be tailored to the Cystic Fibrosis community, to increase the chances of longevity. Most published studies of exercise training with Cystic Fibrosis are supervised in hospital based settings. It has been observed that after hospital based training is completed and patients are unsupervised there is a tendency to discontinue exercise programs. Thus if Cystic Fibrosis patients are to benefit from long term exercise a sustainable program which is inclusive of patient preferences is needed.

Where is the research from?
This study was conducted at the Manchester Adult Cystic Fibrosis Centre, by the South Manchester University Hospitals NHS Trust. It was published in Thorax, the official journal of the British Thoracic Society.

What kind of research was this?
This study was a randomised control trial, that assessed the effectiveness of an individualised unsupervised home-based exercise program in an adult population with Cystic Fibrosis. Randomised control trials are used to distribute participants in an unbiased way, and are considered a high level research method by the National Health and Medical Research Council (NHMRC).

What did the research involve?
All subjects were patients who attended the Adult CF Centre in Manchester, and had a documented history of Cystic Fibrosis. The subjects were randomised to an active group (n=30) or a control group (n=18). All subjects underwent a baseline assessment, the primary measure was fitness level as assessed by lactate concentration at the end of a constant work rate for both arm and leg ergometric testing. Secondary measures were heart rate and pulmonary function, which were measured using spirometric parameters such as FEV and FVC. These values were reassessed for all subjects at 3 and 6 months, with a final comparison conducted at 12 months.

Active Group
Baseline fitness levels were assessed, and a questionnaire was completed regarding the subjects exercise habits. The questionnaire included questions about exercise preference, which previous similar studies had not included. The participants preferences were used to advise the prescription of their exercise programme. Each session lasted 20 minutes and began with a warm up. The aim was to complete three sessions of lower body exercises and three sessions of upper body exercises per week. The starting weight for upper body exercises was outlined and further information regarding progression of weights and sets was provided. The active subjects were asked to keep a training diary to keep track of their progress. Meetings were conducted at 4 week intervals to evaluate progress.

Control Group
Control subjects were not asked to alter their exercise levels, or change their activity. If they expressed a desire to increase the amount of exercise they were doing, this was not discouraged. The control group were not asked to keep a training/exercise diary. So if their exercise level did increase, this information was not included in the study, and could have had an impact on results. All subjects continued their usual treatment regimens, which are assumed to be of a similar nature for all individuals. But without further information being provided in the article it is not known how treatment may differ for each patient.

What were the basic results?
Mean (SD) baseline non-exercise data for active and control subjects.

Pulmonary Function
There was a clear trend towards better pulmonary function in the active group. The mean FEV1 in the active group after 12 months was only 67ml lower than baseline. The control group saw a larger fall in FEV1 with a decrease of 174ml from baseline. Forced Vital Capacity followed a similar trend, with the active group seeing improvements after 12 months where the control group did not. These results are on trend with previous studies looking at pulmonary function and exercise in Cystic Fibrosis.

Arm and Leg Ergometry
Arm ergometry results at 12 months, observed a small but non-significant reduction in lactate concentration in the active groups. This was the primary measure of exercise tolerance improvements. Leg ergometry showed the main difference between the two groups after 12 months, when both groups performed a constant work rate cycle. There were significant reductions in lactate concentrations (p<0.05) in the active group compared with the control subjects.

What conclusions can we take from this research?
The authors of this study concluded that a training effect can be achieved with a programme of individualised unsupervised home exercise in adults with Cystic Fibrosis over a 1 year period. Additionally and possibly more importantly the study showed that lung function is preserved in patients who exercise long term. Although short term intensive supervised programs have shown excellent short term results, a long term approach that takes into account patients' preferences for exercise may have advantages long term. Neither this study in adults nor the 3 year study in children claim to have conclusively answered the long term prognosis resulting from regular exercise, as neither study performed a follow up assessment.

A feature that favours exercise adherence in Cystic Fibrosis patients is that Cystic Fibrosis patients regard exercise as an area of their treatment over which they have control. Unlike other aspects of treatment, fear of increasing disease severity does not drive adherence to exercise. However the kind of autonomy subjects in this study where provided around exercise and their preferences, does support strong patient adherence.

The strongest research at present in support of exercise programmes for Cystic Fibrosis patients is a Cochrane systematic review of over 13 studies in the topic area. It stated there was limited evidence that short or long-term exercise has a positive effect on exercise capacity and pulmonary function. The review followed on to highlight the need for further high quality studies to be undertaken. As previously stated the 1 year study in adults concluded that it had observed a significant improvement in both exercise capacity and pulmonary function. How can these results between these two resource differ from each other so greatly? Were the improvements seen in the 1 year study greater because exercise adherence was better. Was it due to the inclusion of subjects' individual preferences when exercise programmes were initially prescribed? High quality randomised controlled trials are needed to comprehensively assess the benefits of exercise programmes in people with cystic fibrosis and answer whether there are benefits to exercise being individualised for patients.

Practical advice
While the effect of exercise on pulmonary function and exercise capacity remains somewhat unclear, exercise training is already a part of regular outpatient care offered to most people with Cystic Fibrosis and since there is some evidence to suggest a benefit exists and no negative side effects have been observed, there is no reason to actively discourage exercise for Cystic Fibrosis patients. If risk factors have been assessed by a medical professional and the subject has been given approval to exercise then the patient should feel comfortable to do so.

Further Information
For more information on how to treat and manage Cystic Fibrosis please visit:

Cystic Fibrosis Australia: https://www.cysticfibrosis.org.au/

Lungs in Action are community-based exercise classes for those with chronic lung conditions. To find a suitable location, visit: https://lungsinaction.com.au/class-locations/