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Original article
Lactic acidosis, potassium, and the heart rate deflection point in professional road cyclists
  1. A Lucía1,
  2. J Hoyos2,
  3. A Santalla1,
  4. M Pérez1,
  5. A Carvajal3,
  6. J L Chicharro3
  1. 1Departamento de Ciencias Morfológicas y Fisiología, Universidad Europea de Madrid, Madrid, Spain
  2. 2Asociación Deportiva Banesto, Spain
  3. 3Departamento de Enfermería y Unidad de Investigación, Universidad Complutense de Madrid, Madrid, Spain
  1. Correspondence to:
 Dr Lucía, Departamento de Ciencias Morfológicas y Fisiología, Edificio A, Despacho 330, Universidad Europea de Madrid, E-28670 Madrid, Spain;
 alejandro.lucia{at}mrfs.cisa.uem.es

Abstract

Objective: To determine the influence of lactic acidosis, the Bohr effect, and exercise induced hyperkalaemia on the occurrence of the heart rate deflection point (HRDP) in elite (professional) cyclists.

Methods: Sixteen professional male road cyclists (mean (SD) age 26 (1) years) performed a ramp test on a cycle ergometer (workload increases of 5 W/12 s, averaging 25 W/min). Heart rate (HR), gas exchange parameters, and blood variables (lactate, pH, P50 of the oxyhaemoglobin dissociation curve, and K+) were measured during the tests.

Results: A HRDP was shown in 56% of subjects at about 88% of their maximal HR (HRDP group; n = 9) but was linear in the rest (No-HRDP group; n = 7). In the HRDP group, the slope of the HR-workload regression line above the HRDP correlated inversely with levels of K+ at the maximal power output (r = −0.67; p<0.05).

Conclusions: The HRDP phenomenon is associated, at least partly, with exercise induced hyperkalaemia.

  • anaerobic threshold
  • Conconi test
  • cycling
  • heart rate
  • ramp test
  • HR, heart rate
  • HRDP, heart rate deflection point
  • AT, anaerobic threshold
  • LVEF, left ventricular ejection fraction
  • ECG, electrocardiogram
  • RCP, respiratory compensation point
  • LT, lactate threshold
  • OBLA, onset of blood lactate accumulation

https://doi.org/10.1136/bjsm.36.2.113

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