title: Determining the anaerobic threshold in water aerobic exercises: a comparison between the heart rate deflection point and the ventilatory method.
abstract: OBJECTIVE
  The aim of this study was to compare the cardiorespiratory variables corresponding to the anaerobic threshold (AT) between different water-based exercises using two methods of determining the AT, the heart rate deflection point and ventilatory method, and to correlate the variables in both methods.
  
  
  METHODS
  Twenty young women performed three exercise sessions in the water. Maximal tests were performed in the water-based exercises stationary running, frontal kick and cross country skiing. The protocol started at a rate of 80 cycles per minute (cycle.min-1) for 2 min with subsequent increments of 10 cycle.min-1 every minute until exhaustion, with measurements of heart rate, oxygen uptake and ventilation throughout test. After, the two methods were used to determine the values of these variables corresponding to the AT for each of the exercises. Comparisons were made using two-way ANOVA for repeated measures with Bonferroni's post hoc test. To correlate the same variables determined by the two methods, the intra-class correlation coefficient test (ICC) was used.
  
  
  RESULTS
  For all the variables, no significant differences were found between the methods of determining the AT and the three exercises. Moreover, the ICC values of each variable determined by the two methods were high and significant.
  
  
  CONCLUSIONS
  The estimation of the heart rate deflection point can be used as a simple and practical method of determining the AT, which can be used when prescribing these exercises. In addition, these cardiorespiratory parameters may be determined performing the test with only one of the evaluated exercises, since there were no differences in the evaluated variables.
authors.affiliation: School of Physical Education, Federal University of Rio Grande do Sul, Porto Alegre, Brazil - ana_kanitz@yahoo.com.br.
authors.forename: C L
authors.initials: CL
authors.lastname: Alberton
authors.forename: A C
authors.initials: AC
authors.lastname: Kanitz
authors.forename: S S
authors.initials: SS
authors.lastname: Pinto
authors.forename: A H
authors.initials: AH
authors.lastname: Antunes
authors.forename: P
authors.initials: P
authors.lastname: Finatto
authors.forename: E L
authors.initials: EL
authors.lastname: Cadore
authors.forename: L F M
authors.initials: LF
authors.lastname: Kruel
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D012123:Pulmonary Ventilation / Q000502:physiology*; D013551:Swimming Pools; D055815:Young Adult