Enhancing physical performance in chronic obstructive pulmonary disease

The ambition of all athletes is to outperform competitors in their chosen discipline. To this end, ever more sophisticated training schedules are used to maximise physical performance. In recent years some sportsmen and women have resorted to illegal pharmacological methods to augment their training programmes and so gain an unfair advantage over their rivals. Patients with chronic obstructive pulmonary disease (COPD) are disabled by their inability to carry out many activities of daily living because of exercise intolerance. This leads to increasing social isolation, depression, and dependence. Improving physical performance is therefore an important therapeutic goal in these patients. It has been thought that exercise limitation in COPD was simply due to a limit to pulmonary ventilation. However, a number of observations have indicated that this is not true for many COPD sufferers. Firstly, the relationship between exercise capacity and lung function impairment is poor1 2and bronchodilator therapy often fails to have a meaningful impact on disability in patients with COPD. Furthermore, patients who have their lung function restored to normal by transplantation may not achieve their predicted exercise capacity following the procedure.3 4 Finally, exercise reconditioning during pulmonary rehabilitation results in impressive improvements in exercise capacity while having no impact on lung function impairment.5-7 Other factors are clearly involved in exercise limitation and it is now evident that peripheral skeletal muscle dysfunction is one of the primary determinants of disability in chronic lung disease.8 Far from being illegal, pharmacological improvement of peripheral muscle performance could be of therapeutic benefit in these patients. Observational studies have demonstrated a reduction in muscle strength and bulk in COPD.9-11 These measures have also been shown to predict peak exercise capacity.12 13 A number of techniques have been developed in recent years which have increased our understanding …