title: The upper limit of the cardiorespiratory training zone (40-84%HRR) is overestimated for postmenopausal women.
abstract: OBJECTIVE
  The purpose of this study was to examine the heart rate reserve (HRR) at first and second ventilatory thresholds (VT's) in postmenopausal women and compare it with optimal intensity range recommended by the ACSM (40-84%HRR). An additional aim was to evaluate whether a higher aerobic power level corresponded to a higher HRR at VT's.
  
  
  METHODS
  Fifty-eight postmenopausal women participated in this study (aged 48-69). A graded 25 Wmin(-2) cycle ergometer (Monark E839) exercise protocol was performed in order to assess aerobic power. The heart rate and gas-exchange variables were measured continuously using a portable gas analyzer system (Cosmed K4b). The first (VT1) and the second (VT2) VT's were determined by the time course curves of ventilation and O2 and CO2 ventilatory equivalents. A K-means clustering analysis was used in order to identify VO2max groups (cut-off of 30.5 mlkg(-1)min(-1)) and differences were evaluated by an independent sample t-test. Bland-Altman plots were performed to illustrate the agreement between methods.
  
  
  RESULTS
  The women's HRR values at VT1 were similar to 40% HRR in both VO2max groups. At VT2 both VO2max groups exhibited negative differences (P<0.01) for the predicted 84%HRR intensity (-14.46% in the lower VO2max group and -16.32% in the higher VO2max group).
  
  
  CONCLUSIONS
  An upper limit of 84% overestimates the %HRR value for the second ventilatory threshold, suggesting that the cardiorespiratory target zone for this population should be lower and narrower (40-70%HRR).
authors: Research Center in Sports Sciences, Health and Human Development (CIDESD), University of Trás-os-Montes and Alto Douro, Vila Real, Portugal. Electronic address: faragao@utad.pt.
authors: Florbela
authors: F
authors: Aragão
authors: Maria Helena
authors: MH
authors: Moreira
authors: Ronaldo Eugénio
authors: RE
authors: Gabriel
authors: Catarina Gavião
authors: CG
authors: Abrantes
mesh_terms: D000368:Aged; D015308:Anaerobic Threshold; D015444:Exercise / Q000502:physiology*; D005260:Female; D064368:Healthy Volunteers; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000502:physiology*; D011446:Prospective Studies
keywords: Cardiorespiratory fitness; Exercise intensity; Heart rate reserve; Postmenopausal; Ventilatory threshold