title: Comparison of three methods to identify the anaerobic threshold during maximal exercise testing in patients with chronic heart failure.
abstract: OBJECTIVE
  Exercise training efficiently improves peak oxygen uptake (V˙O2peak) in patients with chronic heart failure. To optimize training-derived benefit, higher exercise intensities are being explored. The correct identification of anaerobic threshold is important to allow safe and effective exercise prescription.
  
  
  METHODS
  During 48 cardiopulmonary exercise tests obtained in patients with chronic heart failure (59.6 ± 11 yrs; left ventricular ejection fraction, 27.9% ± 9%), ventilatory gas analysis findings and lactate measurements were collected. Three technicians independently determined the respiratory compensation point (RCP), the heart rate turning point (HRTP) and the second lactate turning point (LTP2). Thereafter, exercise intensity (target heart rate and workload) was calculated and compared between the three methods applied.
  
  
  RESULTS
  Patients had significantly reduced maximal exercise capacity (68% ± 21% of predicted V˙O2peak) and chronotropic incompetence (74% ± 7% of predicted peak heart rate). Heart rate, workload, and V˙O2 at HRTP and at RCP were not different, but at LTP2, these parameters were significantly (P < 0.0001) higher. Mean target heart rate and target workload calculated using the LTP2 were 5% and 12% higher compared with those calculated using HRTP and RCP, respectively. The calculation of target heart rate based on LTP2 was 5% and 10% higher in 12 of 48 (25%) and 6 of 48 (12.5%) patients, respectively, compared with the other two methods.
  
  
  CONCLUSIONS
  In patients with chronic heart failure, RCP and HRTP, determined during cardiopulmonary exercise tests, precede the occurrence of LTP2. Target heart rates and workloads used to prescribe tailored exercise training in patients with chronic heart failure based on LTP2 are significantly higher than those derived from HRTP and RCP.
authors.affiliation: Department of Cardiology, Antwerp University Hospital, Edegem, Belgium.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Beckers
authors.forename: Nadine M
authors.initials: NM
authors.lastname: Possemiers
authors.forename: Emeline M
authors.initials: EM
authors.lastname: Van Craenenbroeck
authors.forename: An M
authors.initials: AM
authors.lastname: Van Berendoncks
authors.forename: Kurt
authors.initials: K
authors.lastname: Wuyts
authors.forename: Christiaan J
authors.initials: CJ
authors.lastname: Vrints
authors.forename: Viviane M
authors.initials: VM
authors.lastname: Conraads
mesh_terms: D015308:Anaerobic Threshold / Q000502:physiology*; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology
chemical_list: D019344:Lactic Acid