title: Can crossover and maximal fat oxidation rate points be used equally for ergocycling and walking/running on a track?
abstract: OBJECTIVE
  To verify whether exercise intensities at the crossover point (COP) and maximal lipid oxidation (Lipox(max)) can be used interchangeably regardless of exercise mode, this study compared COP, Lipox(max) and maximal fat oxidation rate (MFO) obtained during two modes of submaximal metabolic exercise tests: stationary cycling under laboratory conditions and walking/running on a track.
  
  
  METHODS
  After preliminary indirect maximal progressive tests, 15 healthy subjects randomly performed submaximal exercise tests on a stationary cycle ergometer (E) and on a track (T), during which gas exchanges and substrate oxidation rates were measured.
  
  
  RESULTS
  There were no significant mean differences in COP [heart rate (HR): 149±23 beats.min(-1) (T), 145±28 beats.min(-1) (E); VO(2): 2168±896 mL.min(-1) (T), 2052±714 mL.min(-1) (E)], Lipox(max) [HR: 127±27 beats.min(-1) (T), 126±23 beats.min(-1) (E); VO(2): 1638±839 mL.min(-1) (T), 1696±656 mL.min(-1) (E)] or MFO [498.3±192.0 mg.min(-1) (T), 477.7±221.5 mg.min(-1) (E)] between the two modes of exercise. However, Bland-Altman analysis showed a clear disagreement between the two exercise modes and, in particular, a large random error [bias±random error: for COP, -3.5±53.2 beats.min(-1) (HR), -116.8±1556.4 mL.min(-1) (VO(2)); for Lipox(max), -0.4±43.3 beats.min(-1) (HR), -5.7±1286.4 mL.min(-1) (VO(2)); and for MFO, -20.6±384.9 mg.min(-1)].
  
  
  CONCLUSIONS
  This study showed that, in young, healthy, reasonably fit subjects, exercise mode can affect intensities at the COP and the Lipox(max). These results, which now have to be confirmed in patients with metabolic defects, suggest the need to perform specific tests to make individualized adaptations to physical activity outside of clinical settings.
authors.affiliation: Joseph-Fourier University, Hypoxia Physiopathology Laboratory, 38000 Grenoble, France.
authors.forename: M
authors.initials: M
authors.lastname: Mendelson
authors.forename: K
authors.initials: K
authors.lastname: Jinwala
authors.forename: B
authors.initials: B
authors.lastname: Wuyam
authors.forename: P
authors.initials: P
authors.lastname: Levy
authors.forename: P
authors.initials: P
authors.lastname: Flore
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D015992:Body Mass Index; D018592:Cross-Over Studies; D005080:Exercise Test / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology*; D008297:Male; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000502:physiology*; D005082:Physical Exertion; D012420:Running / Q000502:physiology; D016138:Walking / Q000502:physiology*; D055815:Young Adult