title: Exercise-induced oxyhaemoglobin desaturation, ventilatory limitation and lung diffusing capacity in women during and after exercise.
abstract: Arterial haemoglobin saturation during exercise in healthy young women [eight subjects mean (SEM) age 20.8 (1.8) years] was measured to confirm the theory that young women experience exercise-induced arterial hypoxaemia (EIAH) at a lower relative percentage of maximal oxygen uptake (VO(2max)) than has been documented in their male counterparts. To determine if flow limitation [the percentage of the tidal volume ( V(T)) that met or exceeded the boundary established by multiple maximal expiratory manoeuvres] and/or post-exercise lung diffusing capacity are linked to EIAH in women, and to investigate the influence of exercise intensity and duration on post-exercise carbon monoxide lung diffusing capacity ( D(L, CO)), these parameters were measured during and after three exercise tests (incremental test until exhaustion, 5 km run and 5 km run with sprint). All subjects experienced physiologically significant EIAH (a fall of more than 3% in oxygen saturation of arterial blood from levels at rest) and seven subjects experienced flow limitation during the VO(2max) protocol [mean (SD) 12.2 (8.8)% of V(T)]. Even though there was no significant relationship between aerobic capacity and the degree of flow limitation ( r=0.33, P>0.05), the flow limitation was related to absolute ventilation in the subjects studied ( r=0.82, P<0.05). There was no significant relationship between decrements in post exercise D(L, CO) and EIAH ( r=0.05, P>0.05), however there was a strong correlation between the extent of flow limitation (% of V(T)) and EIAH ( r=0.71). Significant decreases in D(L, CO) lasted for up to 16 h after each of the exercise tests ( P<0.05) and lasted for a further 8 h after the maximal test ( P<0.05). Exercise intensity was the main contributing factor to the observed decreases in post-exercise D(L, CO) with the percentage of VO(2max) attained during the various tests being significantly related to the fall in D(L, CO) for 1, 2, 3, 16 and 24 h after exercise ( P<0.05). As the appearance of flow limitation closely coincided with the appearance of EIAH, the results from the present study suggest that flow limitation is a contributing factor to EIAH in women although the exact mechanism remains unclear.
authors.affiliation: Discipline of Anatomy and Physiology, School of Medicine, University of Tasmania, GPO Box 252-24, Hobart 7001, Australia. J.Walls@utas.edu.au
authors.forename: Justin
authors.initials: J
authors.lastname: Walls
authors.forename: Michael
authors.initials: M
authors.lastname: Maskrey
authors.forename: Richard
authors.initials: R
authors.lastname: Wood-Baker
authors.forename: Wade
authors.initials: W
authors.lastname: Stedman
mesh_terms: D000328:Adult; D001158:Arteries; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology / Q000503:physiopathology*; D019344:Lactic Acid / Q000097:blood; D008176:Lung Volume Measurements; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000378:metabolism*; D010807:Physical Endurance / Q000502:physiology; D011653:Pulmonary Diffusing Capacity; D015656:Respiratory Mechanics; D012680:Sensitivity and Specificity; D012727:Sex Characteristics
chemical_list: D010108:Oxyhemoglobins; D019344:Lactic Acid