title: Determination of lactate threshold by respiratory gas exchange measures and blood lactate levels during incremental load work.
abstract: OBJECTIVE
  The purpose of this investigation was the determination of the lactate threshold (LT) by selected respiratory gas exchange measures and venous blood lactate levels during incremental load work on a mechanically braked cycle ergometer.
  
  
  METHODS
  Repeated measures design.
  
  
  METHODS
  Human Performance Laboratory.
  
  
  METHODS
  Eight healthy trained soccer players (mean age 21.9 +/- 3.0 yr, mean VO2max = 59.2 +/- 3.6 ml.kg.min-1).
  
  
  METHODS
  Subjects conducted two incremental load work tests. Incremental load work was increased by 1 kilopond (kp) every third minute at 60 rpm until voluntary exhaustion. Blood samples from a forearm vein were collected during the second trial (T2) only and analyzed for lactic acid [LA-].
  
  
  RESULTS
  One-way analysis of variance (ANOVA) with repeated measures indicated no statistically significant difference between the two tests for maximal oxygen uptake (VO2max), maximal carbon dioxide production (VCO2max), maximal heart rate (HRmax), maximal pulmonary ventilation (VEBTPSmax) and lowest ventilatory equivalent of oxygen (VE/VO2), respectively; however, there was a significant difference among the oxygen uptake (VO2) values at the LT for the four determination methods. In our subjects, the measured (mean +/- SD) VE/VO2 in relation to VO2 for the first trial (T1) of 22.9 +/- 1.9 occurred at VO2 of 1.27 +/- 0.8 l.min-1. The lowest VE/VO2 and the onset of [LA-] accumulation calculated from individual exponential equations relating VE to VO2 yielded VO2 values of 1.77 +/- 0.18 and 1.74 +/- 0.25 l.min-1 for the T2. Utilizing natural log for lactate ln [LA-] to natural log for ln (VO2) equations, the LT for T2 occurred at VO2 of 1.30 +/- 0.70 l.min-1.
  
  
  CONCLUSIONS
  LT was best predicted by the measured lowest VE/VO2 and the plot of the ln [LA-] to ln VO2 relationship. The methods used in this study provide a valid estimate of the LT and support the use of measured lowest VE/VO2 as an indirect measure of the LT.
authors.affiliation: Department of Clinical Sciences, University of Massachusetts, Lowell.
authors.forename: S P
authors.initials: SP
authors.lastname: von Duvillard
authors.forename: L M
authors.initials: LM
authors.lastname: LeMura
authors.forename: D W
authors.initials: DW
authors.lastname: Bacharach
authors.forename: P
authors.initials: P
authors.lastname: Di Vico
mesh_terms: D000140:Acidosis, Lactic / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology; D000328:Adult; D015308:Anaerobic Threshold; D000704:Analysis of Variance; D001944:Breath Tests; D002245:Carbon Dioxide / Q000032:analysis*; D005069:Evaluation Studies as Topic; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D008297:Male; D010100:Oxygen / Q000032:analysis*; D010101:Oxygen Consumption; D005082:Physical Exertion; D011237:Predictive Value of Tests; D011659:Pulmonary Gas Exchange
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen