title: Measurement precision of the anaerobic threshold by means of a portable calorimeter.
abstract: BACKGROUND
  Many methods are used for determining the Anaerobic Threshold (AT) by means of sophisticated ergospirometer.
  
  
  OBJECTIVE
  To test the AT variation, detected by mathematical models and visual inspection, when low cost ergospirometer is used and intended for clinical application.
  
  
  METHODS
  Seventy nine apparently healthy subjects were volunteers in this study; from these, 57 men. The VO₂(max) and the ventilatory threshold were determined by indirect, open-circuit calorimetry. The electro-enzymatic method was used for analyzing the lactacidemia and direct determination of the Lactate Threshold (LT). The AT was determined by two mathematical methods (MM(RSS) and MM(slope)), based on the gases exchange, and by the log-log visual method, for determining the LT. Two independent investigators determined the AT through visual inspection of three graphs, considering two methods (AT₋(a)= V-slope, EqV; and AT₋(b) = V-slope, EqV and ExCO₂). The data were analyzed by means of parametric statistics for determining the differences between AT₋(a) versus ExCO₂, MM(RSS) and MM(slope); AT-b versus MM(RSS) and MM(slope); and LT versus AT₋(a), AT₋(b), MM(RSS) and MM(slope).
  
  
  RESULTS
  The MM(slope) was the only method that presented a significant difference between the AT₋(a) and AT₋(b) (p=0.001), with CV% >15. LT versus MM(slope) did not present significant difference (p=0.274), however, it was observed a high CV (24%).
  
  
  CONCLUSIONS
  It was concluded that with the low cost equipment, the MM(RSS) and AT₋(a) methods can be used for determining the TAn. The MM(slope) method did not present satisfactory precision to be employed with this equipment.
authors.affiliation: Universidade Federal do Rio de Janeiro, RJ, Brasil. nogueira_ufrj@hotmail.com
authors.forename: Fernando dos Santos
authors.initials: FS
authors.lastname: Nogueira
authors.forename: Fernando Augusto Monteiro Sabóia
authors.initials: FA
authors.lastname: Pompeu
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D015308:Anaerobic Threshold / Q000502:physiology*; D000704:Analysis of Variance; D002153:Calorimetry, Indirect / Q000295:instrumentation / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008954:Models, Biological; D012189:Retrospective Studies; D013147:Spirometry / Q000191:economics / Q000295:instrumentation*; D055815:Young Adult
chemical_list: D019344:Lactic Acid