The Mozart study: a relation between dynamic hyperinflation and physical activity in patients with chronic obstructive pulmonary disease?

Summary Background Many patients with chronic obstructive pulmonary disease ( COPD ) experience dyspnoea during exercise, resulting in a reduction of physical activity ( PA ). Dynamic hyperinflation ( DH ) is seen as a major cause of dyspnoea in COPD . Objective The objective of the current study was to investigate the relationship between DH , in terms of the amount of DH and the development and recovery rate of DH in patients with COPD , and PA . Methods Thirty‐five patients with stable COPD were included from an outpatient clinic (14 GOLD II and 21 GOLD III , median age 65). PA was assessed using an accelerometer. Subjects underwent metronome‐paced tachypnoea ( MPT ) to induce DH . To quantify the amount of DH during MPT , a decrease in inspiratory capacity ( IC ) or a change in IC as percentage of total lung capacity was used. Results No significant correlations were found between the parameters describing DH and PA . Secondary correlation analyses showed a negative correlation between static hyperinflation ( SH ) and PA ( r  = −0·39; P  = 0·02). The pattern of breathing during MPT and the test itself showed high interpatient variability. Conclusions The absence of a significant correlation between DH and PA is contrary to previous studies. SH did show a correlation with PA . The variety in results and the technical difficulties in execution of the measurements ask for a new, more reliable, method to detect DH and investigate its relation with PA in patients with COPD .