Creatine supplementation in COPD

M ultidisciplinary pulmonary rehabilitation now has an established place in the management of chronic disabling respiratory diseases, particularly chronic obstructive pulmonary disease (COPD). Rehabilitation is being taken up widely on the strength of the accumulated evidence. While the effectiveness of rehabilitation is accepted, there is still considerable interest in refining and researching the individual modalities of treatment that make up the multidisciplinary intervention. Exercise training is a key component of an effective pulmonary rehabilitation programme. In recent years a number of approaches have been taken in an effort to enhance the effectiveness of physical training, particularly for more severely disabled patients who may have reduced muscle bulk and whose baseline exercise capacity is particularly low. Broadly, strategies have either concentrated on acute interventions that enable subjects to train at higher intensity or have focused on altering underlying skeletal muscle functioning. An example of the former approach is the inclusion of oxygen supplementation during training in patients with hypoxaemia. 3 Acute oxygen supplementation does enhance exercise performance and allows a higher work output for training. However, its use in training programmes has not been found to improve the overall outcomes of rehabilitation. Taking the alternative approach, attempts to restore muscle function have seen a crossover of techniques used for performance enhancement in sport and other areas of medicine. These interventions have included nutritional supplementation, the use of anabolic steroids, and the use of growth hormone. These kinds of intervention do increase muscle bulk but do not tend to produce beneficial gains in terms of whole body exercise and patient based outcomes in patients disabled by COPD and low muscle mass. The underlying causes of the reduction in muscle mass in patients with COPD are likely to be heterogeneous and complex. They include imbalance in caloric intake and expenditure, disuse, the systemic effects of glucocorticoid steroid treatment, low circulating androgen levels, and systemic inflammation. The high prevalence of low muscle mass in patients with COPD is now recognised, as is the adverse impact of malnutrition in terms of disability, health service usage, and mortality.