Cystic fibrosis (CF) is the most common fatal inherited disease in Caucasian populations. In the European Union, it has a prevalence of 0.737 per 10,000, which is similar to that seen in the USA Citation[1]. CF is a multisystem disease, although the primary clinical manifestations usually occur in the lungs and include cough, excess sputum, shortness of breath and respiratory muscle fatigue, resulting in progressive lung damage and eventual death from respiratory failure. The daily treatment burden of CF is high and people may spend up to 2 h per day on a wide range of CF therapies, including taking medications and undergoing physiotherapy treatments such as regular airway clearance and exercise Citation[2]. Not surprisingly, CF physiotherapists and people with CF need clear information and guidance on how to incorporate exercise into an already arduous daily regime. Exercise and physical activity have been identified as a key area for research at a recent European Cystic Fibrosis Society Allied Health Profession and Nursing consensus meeting in November 2009. The need for clarity around the importance of exercise in CF is also evident by questions posed on a European CF expert advice site for patients and care team members Citation[101]. Examples of questions on this website include:
• “My child wants to attend a sports cluster may I let him do it? What sport is most beneficial for him?” (asked by parent of child with CF);
• “Which sports are not good for patients with CF?” (asked by person with CF);
• “Until now I didn’t really like exercise…strangely enough I have started enjoying myself and want to know what is best to improve my condition?” (asked by person with CF).
There is cumulative evidence of the benefit of increasing exercise in CF in terms of improved participation in activities of daily living, improved quality of life and reduced hospital admissions. A Cochrane systematic review demonstrated that exercise has a positive effect on exercise capacity, strength and lung function in CF Citation[3]. Following a number of key studies, it is now generally accepted that exercise tolerance is linked to a decline in lung disease and is an independent predictor of survival Citation[4–7]. Consequently, the importance of exercise in the management of CF has been well recognized and relevant CF guidelines include exercise as a key component of routine management Citation[8,102].
The traditional exercise message emphasized structured exercise, which is typically prescribed according to a specific intensity, duration and frequency. Recent literature in both health and chronic disease now emphasizes the importance of physical activity and, consequently, incorporates a broader range of options for being active Citation[103]. In addition to moderate physical activity, recent emphasis has been on the importance of the balance between activity and inactivity Citation[9]. Emerging research shows that, compared with the general population, people with CF are below the recommended targets for physical activity and spend less time in moderate-intensity activities than the healthy population Citation[10]. There is little information on the balance of activity and inactivity in CF, therefore its relevance in CF needs to be researched further. Moderate-intensity physical activity is associated with better fitness levels and this could potentially contribute to increased life expectancy Citation[10,11]. Within the CF population, there is some evidence that females with CF may be less active than males with CF Citation[12,13]. These differences in physical activity levels between males and females may contribute to the greater decline in lung function in females with CF Citation[14].
With increasing emphasis on physical activity, perhaps the time is right for physiotherapists and other health professionals currently involved in exercise assessment or exercise prescription and advice to ask some important questions, such as is there clarity on what levels of exercise/physical activity people with CF should be doing (i.e., how much is enough)? How can adherence to exercise in CF be optimized? What strategies should we use to increase participation in regular exercise/physical activity in CF? How do we measure exercise/physical activity in the clinical setting and how often should it be measured? To address the first of these questions, we can look toward some of the new physical activity guidelines. Until disease becomes severe, the current guidelines for physical activity for healthy children and adults are likely to be applicable in CF and have been recommended as the basis for exercise advice in CF Citation[8,15,103]. These guidelines make specific reference to the weekly amount of moderate-intensity aerobic activity and strengthening activity required to achieve health benefits in healthy adults and children. So, for people with CF without significant disease progression, management should include regular assessment of fitness, exercise advice, monitoring of adherence to exercise advice, education about the benefits of exercise and, where appropriate, introduction of strategies to maintain or improve exercise levels. These are all important messages in CF where the treatment burden is high and decisions are being made on which treatments/behaviors patients can incorporate into their daily lives. As disease becomes more severe, people with CF are likely to need individually tailored exercise programs incorporating more interval-type training and frequent re-evaluation by the physiotherapist Citation[16,17]. Consideration of the need for training oxygen and ventilatory support will also become important Citation[18]. For all patients, additional exercises focused on CF-specific abnormalities may also be important, such as postural and flexibility exercises. Evidence from healthy individuals shows a clear dose relationship between activity and health outcomes and supports the concept of accumulation of physical activity throughout the day. Research is needed to confirm that the recommendations in healthy patients can be translated into people with CF and ascertain how important the balance between activity and inactivity in everyday life is in CF Citation[9]. In the meantime, physiotherapists probably need to encourage not only more physical activity but discourage sedentary time, when appropriate.
General adherence to treatments in CF is challenging and adherence to exercise is lower compared with other treatments Citation[2,19,20]. Self-efficacy and outcome expectations are important mediators of adherence behavior Citation[21]. Minimizing the perceived barriers to exercise/physical activity in CF and optimizing motivators is likely to influence the success of any program Citation[22]. Patients’ perception of exercise can be positive compared with other treatments as exercise is focused on health promotion rather than management of their chronic illness. The CF team need to capitalize on this and ensure that they optimize adherence so that the message ‘exercise is medicine’ is acknowledged and considered an important component of treatment. Simple strategies to increase adherence include: setting individual goals for patients, ensuring that people choose a range of activities they enjoy (supervised versus unsupervised; team sports versus individual physical activity); and promoting social inclusion and familial support, for example, by incorporating ‘fitness’ games Citation[23,24]. Schemes such as the ‘Healthwise Scheme’ in the UK can also improve social inclusion; however, such schemes raise additional questions regarding cross-infection and payment issues. The role and function of the CF team for patients who decide to exercise in this type of setting requires clarification. Recent research, albeit in other conditions, has demonstrated the value of various behavioral intervention programs in increasing physical activity Citation[25,26]. These may lead to better longer-term adherence than structured activity. Further research is needed to understand the complex relationship between gender, severity and exercise adherence and to develop interventions appropriate to improve adherence to exercise/physical activity. Nutritional intake needs consideration in people with CF who are physically active and physiotherapists need to work closely with the CF dietician to ensure that they receive adequate supplements Citation[27].
There is no real agreement on what exercise test(s) should be used to assess exercise capacity and this varies widely from center to center, depending on local resources and expertise. In the UK, exercise tests are frequently part of annual assessment and therefore patients usually have at least one exercise test performed annually. Some centers will monitor changes in exercise capacity and give advice on exercise on the basis of exercise test results. What is becoming increasingly obvious is that exercise tests are only a part of the picture as they measure an individual’s capacity to exercise rather than actual engagement in activity, which is much more difficult to measure. Current methods fall into two broad categories: subjective methods (questionnaires and diaries) and objective methods (motion sensors such as pedometors or accelerometers). While questionnaires have a number of advantages in that they are inexpensive and easy to apply, there is some debate regarding their accuracy and variability, which can limit their usefulness in monitoring activity levels. The selection of a specific motion sensor requires special consideration of the instrument’s clinical utility, clinimetric properties, cost and purpose for use as an alternative objective measure Citation[28]. This area is evolving rapidly and it may not be long before we have an accurate method of objectively assessing physical activity levels in CF that would be appropriate for use in clinical practice and across disease severity. Consideration of the use of other outcome measures to enhance our understanding of physical activity behavior may also be important and some examples may include treatment adherence and burden, self-efficacy and readiness to change Citation[2,29–31].
In conclusion, exercise is already part of the care package offered in CF centers and in our view it should be considered a core part of CF management. Physiotherapists are well placed within the CF team to take a lead role in implementing the exercise recommendations and ensuring that adherence to exercise is optimized in all people with CF, irrespective of their disease severity.
Financial & competing interests disclosure
The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.
No writing assistance was utilized in the production of this manuscript.
References
- Farrell PM. The prevalence of cystic fibrosis in the European Union. J. Cyst. Fibros.7(5), 450–453 (2008).
- Sawicki G, Sellers D, Robinson W. High treatment burden in adults with cystic fibrosis: challenges to disease self management. J. Cyst. Fibros.9, 91–96 (2009).
- Bradley JM, Moran F. Physical training for cystic fibrosis. Cochrane Database Syst. Rev.1, CD002768 (2008).
- Nixon PA, Orenstein DM, Kelsey SF, Doerschuk CF. The prognostic value of exercise testing in patients with cystic fibrosis. N. Engl. J. Med.327(25), 1785–1788 (1992).
- Klijn PH, Oudshoorn A, van der Ent CK, Ann der Net J, Helders PJ. Effects of anaerobic training in children with cystic fibrosis: a randomised controlled study. Chest125(4), 1299–1305 (2004).
- Pianosi P, LeBlanc J, Almudevar A. Peak oxygen uptake and mortality in children with cystic fibrosis. Thorax60, 50–54 (2005).
- Pianosi P, LeBlanc J, Almudevar A. Relationship between FEV1 and peak oxygen uptake in children with cystic fibrosis. Pediatr. Pulmonol.40(4), 324–329 (2005).
- Bott J, Blumenthal S, Buxton M et al. BTS/ACPRC guidelines: physiotherapy management of the adult, medical, spontaneously breathing patient. Thorax64(Suppl. 1), i1–i51 (2009).
- Brown J, Bauman AE, Owen N. Circles in physical activity research? Br. J. Sports Med.43, 86–88 (2009).
- Troosters T, Langer D, Vrijsen B et al. Skeletal muscle weakness, exercise tolerance and physical activity in adults with cystic fibrosis. Eur. Respir. J.33, 99–106 (2009).
- Hebestreit H, Kieser S, Rudiger S et al. Physical activity is independently related to aerobic capacity in cystic fibrosis. Eur. Respir. J.28, 734–739 (2006).
- Myers LB. An exploratory study investigating factors associated with adherence to chest physiotherapy and exercise in adults with cystic fibrosis. J. Cyst. Fibros.8, 425–427 (2009).
- Selvadurai HC, Blimkie CJ, Cooper PJ, Mellis CM, Van Asperen PP. Gender differences in habitual activity in children with cystic fibrosis. Arch. Dis. Child.89, 928–933 (2004).
- Schneiderman-Walker J, Wilkes D, Strug L et al. Sex differences in habitual physical activity and lung function decline in children with cystic fibrosis. J. Pediatr.147(3), 321–326 (2005).
- American College of Sports Medicine. ACSM’s Guidelines for Exercise Testing and Prescription (8th Edition). Lippincott Williams and Wilkins, PA, USA (2009).
- Association of Chartered Physiotherapists in Cystic Fibrosis. Clinical Guidelines for the Physiotherapy Management of Cystic Fibrosis. Cystic Fibrosis Trust, Kent, UK (2002).
- O’Neill B, Bradley J, Moran F. Exercise in the treatment of respiratory disease. In: Exercise Therapy. Gormley J, Hussey J (Eds). Blackwell Publishing, Oxford, UK, 135–168 (2005).
- Elphick HE, Mallory G. Oxygen therapy for cystic fibrosis. Cochrane Database Syst. Rev.1, CD003884 (2009).
- Myers LB, Myers F. The relationship between control beliefs and self-adherence in adults with cystic fibrosis. Psychol. Health Med.4, 387–392 (1999).
- White W, Stiller K, Hansel N. Adherence of adult cystic fibrosis patients with airway clearance and exercise regimes. J. Cyst. Fibros.6, 163–170 (2007).
- Sirur R, Richardson J, Wishart L, Hanna S. The role of theory in increasing adherence to prescribed practice. Physiother. Can.61, 68–77 (2009).
- Prasad SA, Cerney FJ. Factors that influence adherence to exercise and their effectiveness: application to cystic fibrosis. Pediatr. Pulmonol.34(1), 66–72 (2002).
- Wilkes DL, Schneiderman JE, Nguyen T et al. Exercise and physical activity in children with cystic fibrosis. Paediatr. Respir. Rev.10, 105–109 (2009).
- Hebestreit H, Kieser S, Junge S et al. Long-term effects of a partially supervised conditioning programme in cystic fibrosis. Eur. Resp. J.35, 578–583 (2010).
- Hospes G, Bossenbroek L, ten Hacken NHT, van Hengel P, de Greef MHG. Enhancement of daily physical activity increases physical fitness of outclinic COPD patients: results of an exercise counseling program. Patient Educ. Couns.75, 274–278 (2009).
- Müller-Riemenschneider F, Reinhold T, Nocon M, Willich SN. Long-term effectiveness of interventions promoting physical activity: a systematic review. Prev. Med.47(4), 354–368 (2008).
- Wideman L, Baker C, Brown F, Kocher P, Consitt LA, Ambrosius WT. Substrate utilization during and after exercise in mild cystic fibrosis. Med. Sci. Sports Exerc.41(2), 270–278 (2009).
- Pitta F, Troosters T, Probst VS, Spruit M, Decramer M, Gooselink R. Quantifying physical activity in daily life with questionnaire and motion sensors in COPD. Eur. Respir. J.27, 1040–1055 (2006).
- Marcus BH, Rossi JS, Selby VC, Niaura RS, Abrams DB. The stages and processes of exercise adoption and maintenance in a worksite sample. Health Psychol.11(6), 386–395 (1992).
- Marcus BH, Simkin LR. The stages of exercise behaviour. J. Sports Med. Phys. Fitness33, 83–88 (1993).
- Quittner AL, Buu A, Messer MA, Messer AC, Watrous M. Development and validation of the cystic fibrosis questionnaire in the United States. Chest128(4), 2347–2354 (2005).
Websites
- Expert Advice on Cystic Fibrosis www.ecorn-cf.eu
- CF Trust Exercise Fact Sheet www.cftrust.org.uk/aboutcf/publications/factsheets
- US Department of Health and Human Services. Physical Activity Guidelines for Americans 2008 www.health.gov/paguidelines/pdf/paguide.pdf