The relationship between physical activity and quality of life in chronic lung disease

It is widely believed that the ability to exercise is related to the quality of life. Patients with chronic lung disease are characterized by progressive physical disability associated with dyspnoea, loss of fitness and social isolation. Functional assessment of chronic lung disease includes measures of impairment (lung function), disability (exercise performance) and handicap (Health-Related Quality of Life (HRQoL)). These measures do not relate closely to each other. HRQoL questionnaires examine the psychosocial handicap which follows disability, and are influenced by dyspnoea and anxiety rather than exercise performance. Pulmonary rehabilitation, which includes exercise training, improves exercise performance but this is not necessarily reflected in HRQoL. Where exercise performance and HRQoL do improve after rehabilitation the relationship may not be causal. It is possible that the major determinants of quality of life in patients with chronic lung disease are not necessarily physical limitation or related to health, but associated with the social deprivation and isolation which accompany it.