title: Severe hypoxemia induced by prolonged expiration and reduced frequency breathing during submaximal swimming.
abstract: The purpose of this study was to examine the metabolic responses during submaximal swimming with self-selected normal breathing (N) and prolonged expiration along with reduced frequency breathing (RB). Ten male swimmers (age: 23.1 ± 2.2 years; VO2max: 47.3 ± 7.2 ml · kg-1· min-1) performed 75-, 100-, 175-, 200-, 275-, 300-, 375- and 400-m trials with N and RB at intensity corresponding to 90% of the critical speed. In RB condition, all trials longer than 75 m were interspersed with 25 m of self-selected N in regular intervals. In RB, oxygen saturation during recovery was decreased compared to starting values after 75, 100, 175, 275 and 375 m (78-91%, P < 0.05), while it remained unchanged after all trials in N condition (98 ± 2%, P > 0.05). Lactate concentration was higher in RB than in N after 400 m (4.3 ± 1.5 vs. 3.3 ± 1.7 mmol · l-1, P < 0.05). During recovery after the 375-m trial, partial pressure of carbon dioxide was increased and pH was decreased in RB compared to N condition. Prolonged expiration along with RB provokes severe hypoxemia during the recovery period after swimming, which is restored with self-selected N during submaximal swimming.
authors.affiliation: a Department of Aquatic Sports, School of Physical Education and Sport Science , National and Kapodistrian University of Athens , Athens , Greece.
authors.forename: Argyris G
authors.initials: AG
authors.lastname: Toubekis
authors.affiliation: a Department of Aquatic Sports, School of Physical Education and Sport Science , National and Kapodistrian University of Athens , Athens , Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Beidaris
authors.affiliation: a Department of Aquatic Sports, School of Physical Education and Sport Science , National and Kapodistrian University of Athens , Athens , Greece.
authors.forename: Petros G
authors.initials: PG
authors.lastname: Botonis
authors.affiliation: b Department of Sports Medicine and Biology of Exercise, School of Physical Education and Sport Science , National and Kapodistrian University of Athens , Athens , Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Koskolou
mesh_terms: D001639:Bicarbonates / Q000097:blood; D062485:Breath Holding; D002245:Carbon Dioxide / Q000097:blood; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D000860:Hypoxia / Q000209:etiology*; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D010465:Perception; D005082:Physical Exertion / Q000502:physiology; D012119:Respiration; D013550:Swimming / Q000502:physiology*; D055815:Young Adult
chemical_list: D001639:Bicarbonates; D002245:Carbon Dioxide; D019344:Lactic Acid; D010100:Oxygen
keywords: Swimmers; blood pH; hypoventilation; oxygen saturation