title: Stability of the blood lactate-heart rate relationship in competitive athletes.
abstract: BACKGROUND
  The identification of the HR (or RPE) associated with blood lactate concentrations of 2.5 mmol x L(-1)(aerobic threshold) (AerT) and 4.0 mmol x L(-1)(anaerobic threshold) (AnT) is a common method for defining training intensities. It is often assumed that the HR at AerT and AnT changes with changes in fitness, much as the power output (Watts: W) associated with AerT and AnT is known to change.
  
  
  METHODS
  We studied speed skaters (N = 13, 7 male, 6 female) during spring (deconditioned) and fall (conditioned) evaluations, using cycle ergometry (stage duration = 5 min) to determine W, HR, and RPE at AerT, AnT, and at maximal exercise (3000 (female) and 5000 (male) m cycle time trials).
  
  
  RESULTS
  In the spring vs. fall evaluations, the power output at AerT was 127+/-12 vs 162+/-9 W (P<0.05), at AnT was 216+/-14 vs. 230+/-13 W (P<0.05), and at maximal exercise was 341+/-15 vs. 364+/-19 W (P<0.05); HR at AerT was 129+/-6 vs. 130+/-7 bpm (P>0.05), at AnT was 162+/-7 vs. 164+/-7 bpm (P>0.05), and at maximal exercise was 196+/-6 vs. 198+/-5 bpm (P>0.05); RPE at AerT was 2.7+/-0.9 vs. 2.6+/-0.8 (P>0.05), at AnT was 5.3+/-1.0 vs. 5.3+/-0.9 (P>0.05).
  
  
  CONCLUSIONS
  These data suggest that although power output at AerT, AnT, and maximal exercise changes significantly with conditioning, there is no systematic change in the associated values for HR and/or RPE used as practical markers of training intensity. Accordingly, a single well-conducted evaluation may allow evaluation of appropriate training markers that may be longitudinally stable.
authors.affiliation: Department of Exercise and Sport Science, University of Wisconsin-La Crosse, 54601, USA. foster@mail.uwlax.edu
authors.forename: C
authors.initials: C
authors.lastname: Foster
authors.forename: D J
authors.initials: DJ
authors.lastname: Fitzgerald
authors.forename: P
authors.initials: P
authors.lastname: Spatz
mesh_terms: D015308:Anaerobic Threshold; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D019344:Lactic Acid / Q000097:blood*; D008297:Male; D012861:Skating / Q000502:physiology*
chemical_list: D019344:Lactic Acid