Patients with chronic obstructive pulmonary disease (COPD) do usually have decreased tolerance of exercise capacity and impaired quality of life. Several studies have shown that exercise capacity is related relatively weakly to lung functions in this group of patients. The aim of the present study was to find parameter which could better reflect or predict maximal exercise capacity. 19 patients with the diagnosis COPD with mean value of forced expiratory volume in one second (FEV1) 46% predicted (range 21-79%) entering pulmonary rehabilitation program were included into the study. Enrolled patients were chosen to cover the whole range of airway obstruction severity. Post-bronchodilator static and dynamic ventilation parameters were used for evaluation and calculation. Quality of live was measured using St. George's respiratory questionnaire (SGRQ), evaluating symptoms, activity and impact of the disease with range from 0 (the best level) to 100 (the worst level). Values of FEV1 (p < 0.001) and ratio of FEV1 to vital capacity (FEV1/VC, p < 0.001) were significantly positively correlated with 6 minute walking distance (6MWD). FEV1/VC were closely related to 6MWD then FEV1. The degree of hyperinflation expressed by residual volume (RV, p < 0.005) and by ratio of residual volume to total lung capacity (RV/TLC, p < 0.001) significantly negatively correlated with 6MWD. Maximal occlusion mouth pressures (PImax, p < 0.05) were positively related to 6MWD. Total score of SGRQ correlated significantly to maximal exercise capacity. Pulmonary function tests and respiratory muscle function have important impact on exercise tolerance in patients with COPD. Tolerance of exercise capacity is significantly reflected by total score of quality of life in this group of patients.

Keywords: Aged; Exercise Tolerance; Female; Forced Expiratory Volume; Humans; Lung Volume Measurements; Male; Pulmonary Disease, Chronic Obstructive /physiopathology/; Quality of Life; Respiratory Mechanics; Vital Capacity