title: Relationship of post-exercise muscle oxygenation and duration of cycling exercise.
abstract: BACKGROUND
  Aerobic adaptations following interval training are supposed to be mediated by increased local blood supply. However, knowledge is scarce on the detailed relationship between exercise duration and local post-exercise blood supply and oxygen availability. This study aimed to examine the effect of five different exercise durations, ranging from 30 to 240 s, on post-exercise muscle oxygenation and relative changes in hemoglobin concentration.
  
  
  METHODS
  Healthy male subjects (N = 18) performed an experimental protocol of five exercise bouts (30, 60, 90, 120, and 240 s) at 80 % of peak oxygen uptake [Formula: see text] in a randomized order, separated by 5-min recovery periods. To examine the influence of aerobic fitness, we compared subjects with gas exchange thresholds (GET) above 60 % [Formula: see text] (GET60+) with subjects reaching GET below 60 % [Formula: see text] (GET60-). [Formula: see text] and relative changes in concentrations of oxygenated hemoglobin, deoxygenated hemoglobin, and total hemoglobin were continuously measured with near-infrared spectroscopy of the vastus lateralis muscle.
  
  
  RESULTS
  Post-exercise oxygen availability and local blood supply increased significantly until the 90-s exercise duration and reached a plateau thereafter. Considering aerobic fitness, the GET60+ group reached maximum post-exercise oxygen availability earlier (60 s) than the GET60- group (90 s).
  
  
  CONCLUSIONS
  Our results suggest that (1) 90 s has evolved as the minimum interval duration to enhance local oxygen availability and blood supply following cycling exercise at 80 % [Formula: see text]; whereas (2) 60 s is sufficient to trigger the same effects in subjects with GET60 + .
authors.affiliation: Center for Teaching and Learning, Technische Universität München, Connollystraße 32, 80809 München, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Stöcker
authors.affiliation: Center for Teaching and Learning, Technische Universität München, Connollystraße 32, 80809 München, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Von Oldershausen
authors.affiliation: Department for Biomechanics in Sports, Technische Universität München, München, Germany.
authors.forename: Florian Kurt
authors.initials: FK
authors.lastname: Paternoster
authors.affiliation: Department for Preventive Pediatrics, Technische Universität München, München, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schulz
authors.affiliation: Department for Preventive Pediatrics, Technische Universität München, München, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Oberhoffer
keywords: Hyperemia; Interval training; Muscle oxygenation; Near-infrared spectroscopy; Prior exercise