Exercise as it relates to Disease/Aerobic Exercise and its effects on Cystic Fibrosis

What is Cystic Fibrosis?
Cystic fibrosis (CF) is a chronic genetic condition that is caused from the mutation of the Cystic Fibrosis Transmembrane Conductance Regulator gene and affects many systems in the body, predominately the respiratory system. This condition is characterised by a malfunction in the endocrine system which results in abnormal secretion of mucus in both the digestive and respiratory systems. This mucus increases the individuals risk of infection as the bacteria and pathogens are trapped in the respiratory or digestive tracts

At the present, there is no cure for cystic fibrosis; however, there are some promising strategies including chest physiotherapy and regular physical activity which, when implemented correctly, can provide many positive effects and can suppress the signs and symptoms of CF. The effect of aerobic exercise on CF is dependent on the disease severity and intensity and duration of exercise. Exercise intolerance is well known to be a symptom of cystic fibrosis. Some of the other signs and symptoms attributed to cystic fibrosis include:
 * Some breathing difficulties including wheezing and a persistent cough which is increased during physical activity
 * Suppressed appetite
 * Lethargy, which may affect physical activity levels
 * Loss of salt during warmer weather
 * Frequent toilet visits

What are the Effects of Aerobic Exercise on Cystic Fibrosis?
While aerobic exercise has positve effects on the musculoskeletal, cardiorespiratory and immune systems for all individuals, the following list is the effects on aerobic exercise specific to individuals with CF.

Cardiorespiratory System
Aerobic Exercise has been shown to decrease the rate of decline in lung function, which has recorded to be at a rate of approximately 2-3% per year. It also has been shown to improve the transepithelial potential difference in the airway, which enhances the airway clearance and improves mucus removal while also increasing ventilation recruitment in the lungs. Individuals with CF generally display lower maximums in the VO2 testing compared to healthy individuals. However, regular aerobic exercise, alongside age, sex, muscle and lung function may increase VO2max scores. Interestingly, improved VO2max scores in CF have also been shown to improve quality of life measures including improved body image and physical functionality, which create more positive attitudes towards partaking in physical activity.

Ventilation with CF is less efficient than healthy individuals when partaking in physical activity, as there is an increase in respiratory dead space, a high respiratory rate and consequently low tidal volume, which results in a lower rate of gas exchange. However, higher tolerance of exercise as a result of regular aerobic activity has been suggested to improve the tidal volume in the lungs and lower respiratory rate.

Musculoskeletal System
Muscular strength may be lesser in individuals with CF due to hyperinflation and malnutrition, which may result in the fatigue in respiratory muscles during periods of aerobic exercise. From the respiratory inflammation characterised with CF and the insufficient respiratory power and efficiency of the muscle, people with CF generally are disadvantaged compared to their non-CF “healthy” counterparts.

Aerobic exercise has been shown to increase both the strength of muscles involved in the process respiration and the competence of neuromuscular transmission. Positive correlations between walk/run distance and inspiratory muscle strength have been recorded in people with CF. Stronger inspiratory muscle may play a positive role in compensating for reduced lung function over the duration of aerobic exercise.

Aerobic exercise combined with regular cyclic breathing techniques and utilising chest physiotherapy has also conveyed not only increases in cardiovascular endurance but also increases thoracic strength.

Exercise Recommendations
The following are recommendations for individuals with CF partaking in aerobic exercise. . HRmax= maximum heart rate
 * Individuals with CF should consult with their GP for a screening to determine what intensity, duration, type of aerobic exercise that is most applicable to their specific condition
 * Aerobic Exercise should generally be of moderate intensity and duration
 * Implementing regular breathing techniques during exercise alongside chest physiotherapy has also shown to increase the clearance of mucus in the brochi, increase exercise tolerance, reduce the feeling of breathlessness and improve quality of life.
 * Depending upon severity, aerobic exercise should be undertaken:

It should also be noted that not all individuals with CF experience the same benefits or effects of aerobic exercise. While symptoms may be suppressed for some individuals from participating in phyical activity, for other they may be heightened and may experience greater breathing diffculties ,inflamation and mucus secretion. Individual responses may vary depending on a multitude of factors including severity of CF, overall health status and physical actvity levels.