title: Reproducibility of lactate markers during 4 and 8 min stage incremental running: a pilot study.
abstract: OBJECTIVE
  This study examined the reproducibility of speed corresponding to specific lactate markers during incremental treadmill running of normal and prolonged stage durations.
  
  
  METHODS
  Nineteen healthy participants (14 male, 5 female) performed repeated, incremental treadmill running trials of 4 and 8 min stages on separate days to examine the test-retest reproducibility of speed at lactate markers. Two trials were completed for each duration in a randomised order.
  
  
  METHODS
  Fingertip blood samples drawn upon stage completion were analysed for plasma lactate, then used to determine running speed at: 2.0, 3.5, and 4.0 mmol l(-1) fixed blood lactate accumulations (FBLA), a 1 mmol l(-1) rise from baseline, and the markers: the deviation maximum (Dmax), the Dmax of the second curve derivative (D2L(max)), the lactate threshold (LT) and log-log LT.
  
  
  RESULTS
  The 2.0 mmol l(-1) FBLA reported the lowest mean bias between 4 min trials (-0.06 km h(-1)), with the narrowest limits of agreement (LoA) (-1.78 to 1.66 km h(-1)). The Dmax had the second lowest bias (0.14 km h(-1)), D2L(max) the second narrowest LoA (-1.93 to 2.90 km h(-1)). For 8 min stages, the 1 mmol l(-1) rise demonstrated, low mean bias (-0.13 km h(-1)) and narrowest LoA (-1.22 to 0.97 km h(-1)) between trials.
  
  
  CONCLUSIONS
  This preliminary report suggests the reproducibility of running speed at lactate summary markers is influenced by stage duration for incremental treadmill running. Varied marker reproducibility between 4 and 8 min stages indicates different blood lactate response, and therefore workload calculation, according to stage length. Consideration of marker construct is recommended.
authors.affiliation: Department of Sport and Exercise Sciences, University of Chichester, UK. Electronic address: j.gavin@chi.ac.uk.
authors.forename: James P
authors.initials: JP
authors.lastname: Gavin
authors.affiliation: Department of Sport and Exercise Sciences, University of Chichester, UK.
authors.forename: Mark E T
authors.initials: ME
authors.lastname: Willems
authors.affiliation: Department of Sport and Exercise Sciences, University of Chichester, UK.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Myers
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D010865:Pilot Projects; D015203:Reproducibility of Results; D012420:Running / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
chemical_list: D015415:Biomarkers; D019344:Lactic Acid
keywords: Exercise tolerance; Incremental exercise; Lactate testing; Running; Sports medicine; Training prescription