title: The Mozart study: a relation between dynamic hyperinflation and physical activity in patients with chronic obstructive pulmonary disease?
abstract: 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.
authors.affiliation: Department of Pulmonology, Medisch Spectrum Twente, Enschede, The Netherlands.|Technical Medicine, University of Twente, Enschede, The Netherlands.
authors.forename: R W
authors.identifier: http://orcid.org/0000-0001-8468-2544
authors.initials: RW
authors.lastname: van Leuteren
authors.affiliation: Department of Pulmonology, Medisch Spectrum Twente, Enschede, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Dijkhuis
authors.affiliation: Department of Pulmonology, Medisch Spectrum Twente, Enschede, The Netherlands.
authors.forename: F H C
authors.initials: FHC
authors.lastname: de Jongh
authors.affiliation: Department of Pulmonology, Medisch Spectrum Twente, Enschede, The Netherlands.
authors.forename: P D L P M
authors.initials: PDLPM
authors.lastname: van der Valk
authors.affiliation: Telemedicine group, Roessingh Research and Development, Enschede, The Netherlands.
authors.forename: M
authors.initials: M
authors.lastname: Tabak
authors.affiliation: Medical School Twente, Medisch Spectrum Twente, Enschede, The Netherlands.
authors.forename: M G J
authors.initials: MGJ
authors.lastname: Brusse-Keizer
mesh_terms: D056044:Actigraphy / Q000379:methods; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004417:Dyspnea / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D015444:Exercise; D017079:Exercise Tolerance; D005260:Female; D000072936:Fitness Trackers; D006801:Humans; D007320:Inspiratory Capacity; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D012119:Respiration; D013147:Spirometry; D013997:Time Factors
keywords: accelerometry; inspiratory capacity manoeuvre; metronome-paced tachypnoea; static hyperinflation