title: Activity monitoring reflects cardiovascular and metabolic variations in COPD patients across GOLD stages II to IV.
abstract: We investigated whether activity monitoring reliably reflects variations in oxygen transport and utilization during walking in COPD patients. Forty-two patients (14 in each GOLD stage II, III and IV) performed an incremental treadmill protocol to the limit of tolerance. Breath-by-breath gas exchange, central hemodynamic variables and activity monitoring were simultaneously recorded. Physiological variables and accelerometer outputs rose linearly with walking speeds. Strong correlations (r[interquartile range, IQR]) were found between treadmill walking intensity (WI: range 0.8-2.0 ms(-2)) and oxygen consumption (0.95 [IQR 0.87-0.97]), (range 7.6-15.5 ml kg(-1)min(-1)); minute ventilation (0.95 [IQR 0.86-0.98]), (range 20-37 l min(-1)); cardiac output (0.89 [IQR 0.73-0.94]), (range 6.8-11.5 l min(-1)) and arteriovenous oxygen concentration difference (0.84 [IQR 0.76-0.90]), (range 7.7-12.1 ml O2100 ml(-1)). Correlations between WI and gas exchange or central hemodynamic parameters were not different across GOLD stages. In conclusion, central hemodynamic, respiratory and muscle metabolic variations during incremental treadmill exercise are tightly associated to changes in walking intensity as recorded by accelerometry across GOLD stages II to IV. Interestingly, the magnitude of these associations is not different across GOLD stages.
authors.affiliation: National and Kapodistrian University of Athens, Department of Physical Education and Sports Sciences, Athens, Greece; National and Kapodistrian University of Athens, 1st Department of Respiratory Medicine, Pulmonary Rehabilitation Unit, Sotiria Hospital, Athens, Greece; Technological Educational Institute of Lamia, Physiotherapy Department, Lamia, Greece.
authors.forename: E A
authors.initials: EA
authors.lastname: Kortianou
authors.forename: Z
authors.initials: Z
authors.lastname: Louvaris
authors.forename: M
authors.initials: M
authors.lastname: Vasilopoulou
authors.forename: I
authors.initials: I
authors.lastname: Nasis
authors.forename: G
authors.initials: G
authors.lastname: Kaltsakas
authors.forename: N G
authors.initials: NG
authors.lastname: Koulouris
authors.forename: I
authors.initials: I
authors.lastname: Vogiatzis
mesh_terms: D000368:Aged; D002153:Calorimetry, Indirect; D002302:Cardiac Output / Q000502:physiology; D002319:Cardiovascular System / Q000503:physiopathology*; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009043:Motor Activity / Q000502:physiology; D010101:Oxygen Consumption; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange; D012119:Respiration; D016138:Walking / Q000502:physiology
keywords: Activity monitoring; COPD; Cardiac output; Indirect calorimetry; Physical activity; Walking