Cystic Fibrosis (CF) is the most common chronically life-shortening inherited disorder among white populations, affecting approximately 1 in 3,300 Caucasian births. In spite of the discovery of the CF gene in 1989, no curative therapy has yet been found (Kerem et al., 1989). Although this is a multifactorial disease, mainly affecting the lungs and the pancreas, the cause of death in 85% of cases is respiratory failure (CF Foundation 2006).
The pathophysiology of CF lung disease begins early in life with the production of irregular airway surface fluid that results in poor mucociliary clearance and thus blocking of the small airways by mucus. Severe infection of the person's airways and a profound inflammatory response further obstruct the airways with bacteria, not to mention cellular debris from the lysis of great amounts of neutrophils (Konstan, 1994).
The rapid degradation of these cells and the discharge of their intracellular contents, such as filamentous actin and neutrophil-derived deoxyribonucleic acid (DNA), further increase the adhesivity and viscosity of the individuals airway secretions. (Vasconcellos, 1994).
Several trials over the years have displayed how the person's inflammatory response to these early infections, directly influence the chronicity of infection and the progress of respiratory disease. The primary clinical manifestations of CF are reduced exercise capacity, retention of sputum, and breathlessness. (Yankaskas, 2004)
Unfortunately the aforementioned symptoms result in progressive lung deterioration, no matter how much treatment is received by an individual, and tragically, premature death (Orstein et al., 2004). With advances in infection control, however, life expectancy has been extended from a median survival of 20 years in 1981, to a median of 31.3 years as of 1998. (CF Foundation, 1999)
It is clear that in order to maintain lung health, individuals with CF should clear their airways of these secretions to reduce the obstruction of the airways, and therefore reduce inflammation and infection. Thus, individuals with CF become highly dependent upon cough and other techniques that help to clear their airways of the viscuous sputum. Airway clearance therapies (ACTs) have thus long been considered the most fundamental tool in the management of CF airway disease. (Bradley 2006)
Physical fitness has also been associated with improved prognosis. (Nixon et al., 1992)
There are a variety of airway clearance techniques used to remove excess mucus including chest physiotherapy (CPT), positive expiratory pressure therapy, inhalation therapy, high-frequency chest wall oscillation systems, and exercise (Marshall, Rosenfeld, & Ramsey, 2000) (See fig 1)
The primary goals of physical training are to improve exercise capacity, decrease breathlessness and improve muscle strength, although it may also result in airway clearance. Usual outcome measures used to determine the effect of physical interventions include peak or endurance exercise tests; weight and body-mass index and breathlessness scales. Less frequently used outcome measures include specific muscle endurance, strength or flexibility tests; health-related quality of life; medication use, frequency of exacerbations and activity diaries or monitors. (Bradley, 2002)
It is believed that exercise may maintain pulmonary function by improving sputum clearance and reducing residual volume (O'Neill, 1987).Physical activity may potentially delay the onset of osteoporosis by preventing a drop in bone mineral density, a big risk for CF sufferers (Wolman,1995). Physical training could also play an important role in the management of diabetes in CF, as clearly increased exercise patterns will develop appetite and hopefully contribute to a more positive body image (Peebles 1998). Other proposed gains physical training may be decreased anxiety and depression, enhanced feelings of well-being and enhanced performance at work and recreational activities (Scneiderman, 2000).
With the support of the literature, discuss the components of the most effective exercise interventions for this condition (i.e. type, frequency, intensity, duration) (30%)
A physical training intervention is defined as participation in a programme of regular vigorous physical activity designed to improve physical performance or cardiovascular function or muscle strength or any combination of these three (Shephard 1994).
A number of must be taken under consideration when prescribing an exercise programme for a person with CF, in order to have the best results and lessened risks. Obviously the severity of lung impairment, baseline fitness levels, the need to have oxygen administered and a good diet are all undeniably important issues with regard to developing a fitness program for people with CF (Shah, 1998).
As we know, regular aerobic exercises increase an individual's ability to exert themselves for a relatively long period (more than 20 minutes). Aerobic training is named so because the quick transport of oxygen from the air to the active muscle is vital in order to provide for energy to tissues. As a result, this type of workout can be limited by disease conditions affecting the cardiovascular and respiratory systems This type of training has been linked with greater improvement in lung function (forced vital capacity) (Moorcroft, 2004), exercise tolerance (Selvaduri, 2002) and general quality of life (QoL) (Schneiderman, 2000) in CF sufferers.
On the other hand, muscle strengthening exercises are designated as anaerobic workouts as they are usually explosive actions and thus the energy provided comes from other sources and not come directly from oxygen combustion. It has also been associated with improved execise tolerance (Klijn, 2004) and QoL (Enright, 2004).
However the effects of both training modalities have also been questioned in papers such as (De Jong, 2001) and (Cerny, 1989) and such their place in the already hectic schedule of a cystic fibrosis patient is put under question.
However I feel that both forms have enough evidence to back up the claims that they have a very important role to play in the treatment of people with this condition.
To begin with training regimes for people with respiratory defects should kept under supervision . This aim of this is to determine individuals tolerance of exercise and enabling them to assess their own amount of exertion during exercise. HR monitoring, saturometry and level of fatigue are the most common parameters in objectifying the intensity of exertion and assessing exercise tolerance.
Similar to this, the first few sessions of any anaerobic work would also need to be supervised to establish an individuals baseline fitness and establish benchmarks (weight, sets, reps and rest period) and also to educate on proper technique, especially in weightlifting.
By supervising the initial sessions you are laying the groundwork for future adherence in the person as you are giving them the tools to train themselves.
Aerobic training (jogging, cycling etc) should ideally incorporate 3 stages: an initial 3 to 5 minute warm up, a minimum of a 20 minute promgarmme and a 3 to 5 minute cool down to minimize the risk of injury.
Currently the ACSM recommend a work intensity of between 55 -65% of maximal heart rate. In 1994 De Jong et al. used the following equation when determining the predicted maximum HR based on a CF sufferer's age.
MHR (maximum heart rate) = 210 - (0.65 x age).
A person perceived exerertion should be between 3-5 and 5 on a modified Borg scale before they are deemed to be working in the aerobic training zone. Also, O2 saturation should remain above 90%. Persons with severe lung dysfunction such as CF patients occasionally require O2 administered through nasal prongs.
However I believe we should not solely concentrate on aerobic work however. Day to day activities encompass the needs for several types of fitness. For example walking up a stairs or chasing a bus, would both be considered anaerobic exercise rather than aerobic work. Thus, one could argue that anaerobic exercise performance may in fact have more practical applications in the daily life of a CF sufferer than assessment of the more traditional concept of aerobic exercise endurance. Even thought there has been extensive studies on anaerobic exercise, questions still remain in regard to people suffering from obstructive lung disease and whether or not they have limited anaerobic capacity. (Ornstein, 2000)
Anaerobic workouts main function, in CF patients, is muscular strengthening, which can make it easier for them to carry out daily tasks. This training modality could also improve self-esteem. Strauss et al. (1987) proposed that strengthening different muscle groups, such as the quadriceps and many arm muscle groups, through resistance training, increases strength and lean muscle mass in teens cystic fibrosis sufferers. The recommendation given was training three times a week, with 2 sets of 10 reps for each of the strengthening exercises. Flexibility activities were also recommended to prepare for exertion and thus prevent injuries. Subjects also displayed a reduction in residual lung volume, which was attributed to increased elasticity and mobility of the chest wall.
Nevertheless certain key factors that must be taken into consideration in order to maximize the potential benefits of exercise and to reduce the risks associated with poorly adapted exercise programs. People with cystic fibrosis lose more salt through sweat than healthy people do, which places them at a greater risk of complications from dehydration, so appropriate rehydration to replace excess electrolyte loss is important.
Potential adverse events from physical therapies include dyspnoea, gastro-oesophageal reflux, bronchospasm, hypoxaemia, pain, fatigue, dehydration and haemoptysis, and, to a lesser extent, rib fractures and pneumothorax. However reported incidences of these negative effects are very low according to (Flume et al 2009.)
As already outlined, regular exercise has the potential to improve the ability of a patient with CF to cope with the physical demands of everyday life, and may improve prognosis. Unfortunately exercise Intolerance is common in cystic fibrosis.
Progressive respiratory disease results in an abnormal ventilatory response to exercise in CF. This contributes to dyspnoea (shortness of breath) and is a major limiting factor to exercise tolerance in this population (O'Neill 1987).
Since many patients live at long distance from their CF centre, home-based programs may be the most feasible. However, studies of home-based, but minimally supervised interventions have been limited, with mixed results. Holzer et al 1984 reported significant compliance problems and no notable improvement in fitness when using standardized programmes.
However there have been a few studies that have suggested how to overcome compliance issues. Schneiderman et al. conducted a study in 1999 that a involved a 3 year follow up intervention. They had great success with this and reported that pulmonary function declined slower in the intervention group than in the control group, indicating a benefit for individuals with CF who participate regularly in aerobic exercise. He also found consistent compliance (69-91%) with the home exercise program and a self-reported positive attitude toward exercise. I think the key to this study was that the subjects were treated as people rather than subjects. They were encouraged to partake in their favourite aerobic activity 3 times a week for at least 20 minutes. Also there was regular contact between the subjects and the testers (every 4-6 weeks); in addition to clinical visits and regular telephone calls, yearly incentives, such as sports bags and T-shirts, were offered to the patients to support their continued participation compliance. After the three year study period, the exercise group indicated that the prescribed exercise protocol (3.times. per.week.for a minimum of 20 minutes) was feasible to maintain, thus providing further evidence of the feasibility and value of including an aerobic exercise program in the conventional treatment regimen of patients with CF. Another study by Bernard et al 2008 investigated the idea of a token economy for increasing and maintaining exercise in three children with CF to positive compliance results. (see fig 2)
Conclusion
There is some evidence to support the inclusion of physical training in the care-management plan of CF. The benefits obtained from including physical training may be influenced by the type of training programme, and the inclusion of both aerobic and anaerobic training are.important. Exercise is already part of the care package offered to most patients with CF, and there is no real evidence to actively discourage this. Aerobic exercise is recommended for patients with cystic fibrosis as an supplementary therapy for airway clearance and its additional benefits to overall health.
Anaerobic training warrants additional investigation both in contrast to and in conjunction with aerobic training.
Finally, adherence to physical training is important because exercise capacity may be an independent prognostic risk factor in CF (Nixon 1992). Nonadherence to prescribed physical training may contribute to worsening signs and symptoms of respiratory disease and a reduced ability to perform activities of daily living and thus ultimately have a detrimental affect on the individual's prognosis
Many questions as to the precise role of exercise in the treatment of CF remain. Investigations must continue to address variables that may confound the relationship between exercise therapy and CF, including disease severity, duration and intensity of training, compliance with the prescribed exercise program, type of training setting (supervised vs unsupervised), genetic predisposition to aerobic endurance, type of exercise, and other therapy modalities.
