title: Pain threshold is achieved at intensity above anaerobic threshold in patients with intermittent claudication.
abstract: OBJECTIVE
  Walking training is considered as the first treatment option for patients with peripheral arterial disease and intermittent claudication (IC). Walking exercise has been prescribed for these patients by relative intensity of peak oxygen uptake (VO2peak), ranging from 40% to 70% VO2peak, or pain threshold (PT). However, the relationship between these methods and anaerobic threshold (AT), which is considered one of the best metabolic markers for establishing training intensity, has not been analyzed. Thus, the aim of this study was to compare, in IC patients, the physiological responses at exercise intensities usually prescribed for training (% VO2peak or % PT) with the ones observed at AT.
  
  
  METHODS
  Thirty-three IC patients performed maximal graded cardiopulmonary treadmill test to assess exercise tolerance. During the test, heart rate (HR), VO2, and systolic blood pressure were measured and responses were analyzed at the following: 40% of VO2peak; 70% of VO2peak; AT; and PT.
  
  
  RESULTS
  Heart rate and VO2 at 40% and 70% of VO2peak were lower than those at AT (HR: -13 +/- 9% and -3 +/- 8%, P < .01, respectively; VO2: -52 +/- 12% and -13 +/- 15%, P < .01, respectively). Conversely, HR and VO2 at PT were slightly higher than those at AT (HR: +3 +/- 8%, P < .01; VO2: +6 +/- 15%, P = .04). None of the patients achieved the respiratory compensation point.
  
  
  CONCLUSIONS
  Prescribing exercise for IC patients between 40% and 70% of VO2peak will induce a lower stimulus than that at AT, whereas prescribing exercise at PT will result in a stimulus above AT. Thus, prescribing exercise training for IC patients on the basis of PT will probably produce a greater metabolic stimulus, promoting better cardiovascular benefits.
authors.affiliation: Department of Nutrition, School of Public Health, Exercise Hemodynamic Laboratory, School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil. raphael.dias@upe.br
authors.forename: Raphael Mendes
authors.initials: RM
authors.lastname: Ritti-Dias
authors.forename: Cláudia Lúcia
authors.initials: CL
authors.lastname: de Moraes Forjaz
authors.forename: Gabriel Grizzo
authors.initials: GG
authors.lastname: Cucato
authors.forename: Luis Augusto Riani
authors.initials: LA
authors.lastname: Costa
authors.forename: Nelson
authors.initials: N
authors.lastname: Wolosker
authors.forename: Maria
authors.initials: M
authors.lastname: de Fátima Nunes Marucci
mesh_terms: D000368:Aged; D015308:Anaerobic Threshold; D000704:Analysis of Variance; D055109:Ankle Brachial Index; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005081:Exercise Therapy; D017079:Exercise Tolerance; D005260:Female; D006339:Heart Rate; D006801:Humans; D007383:Intermittent Claudication / Q000503:physiopathology* / Q000628:therapy; D008297:Male; D009043:Motor Activity; D010101:Oxygen Consumption; D010146:Pain; D058729:Peripheral Arterial Disease / Q000503:physiopathology* / Q000628:therapy; D016138:Walking