title: Correlation of gas exchange threshold and first muscle oxyhemoglobin inflection point with time-to-exhaustion during heavy-intensity exercise.
abstract: BACKGROUND
  The twofold aim of the study was to: 1) compare the gas exchange threshold (GET), the first oxyhemoglobin inflection point ([O2Hb]-T), and perceptual threshold as determined during an incremental exercise test, and 2) investigate the link between each threshold and time-to-exhaustion during heavy intensity exercise.
  
  
  METHODS
  Fourteen competitive cyclists performed an incremental exercise test to exhaustion on a cycloergometer to determine the different thresholds and peak workload (Wpeak). The participants then performed a sub-maximal constant workload test (90% Wpeak) to exhaustion to determine time-to-exhaustion. The thresholds were identified from: 1) the first breakpoint in the oxygen uptake vs. carbon dioxide output curve (GET), 2) the [O2Hb]-T, and 3) a rating of 13 in perceived exertion (perceptual threshold: RPE13-T).
  
  
  RESULTS
  Oxygen uptake at the different thresholds was not significantly different (P>0.05). Moreover, GET and [O2Hb]-T were significantly correlated: 1) to each other (r≥0.79; P≤0.001), and 2) to time-to-exhaustion (r=0.81 and r=0.72, respectively; P<0.01). RPE13-T, however, was not significantly correlated with the time-to-exhaustion (P=0.148).
  
  
  CONCLUSIONS
  The anaerobic threshold as identified from GET was concomitant to [O2Hb]-T. Both thresholds were correlated to time-to-exhaustion, and could therefore be used as a performance index in middle-duration events.
authors.affiliation: CETAPS, EA3238, Faculty of Sport Sciences, University of Rouen, Mont-Saint-Aignan, France - jeremy.coquart@yahoo.com.
authors.forename: Jérémy B
authors.initials: JB
authors.lastname: Coquart
authors.affiliation: UDSL, EA4488, University of Lille Nord de France, Ronchin, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mucci
authors.affiliation: CETAPS, EA3238, Faculty of Sport Sciences, University of Rouen, Mont-Saint-Aignan, France.
authors.forename: Maxime
authors.initials: M
authors.lastname: L'hermette
authors.affiliation: Athlete Health and Performance Research Centre, ASPETAR, Doha, Qatar.|Orthopedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Karim
authors.initials: K
authors.lastname: Chamari
authors.affiliation: CETAPS, EA3238, Faculty of Sport Sciences, University of Rouen, Mont-Saint-Aignan, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Tourny
authors.affiliation: UDSL, EA4488, University of Lille Nord de France, Ronchin, France.
authors.forename: Murielle
authors.initials: M
authors.lastname: Garcin
mesh_terms: D000222:Adaptation, Physiological; D015308:Anaerobic Threshold / Q000502:physiology; D001642:Bicycling / Q000502:physiology; D005080:Exercise Test; D005221:Fatigue / Q000503:physiopathology*; D064368:Healthy Volunteers; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D010108:Oxyhemoglobins / Q000378:metabolism*; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
chemical_list: D010108:Oxyhemoglobins