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Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,111
Online ISSN 1827-1928
EXERCISE PHYSIOLOGY AND BIOMECHANICS
Perrey S. 1, 2, Candau R. 2, Borrani F. 2, Millet G. Y. 3, Rouillon J. D. 1
1 Laboratoire des Sciences du Sport Besançon, France
2 Laboratoire Sport Performance Santé, Montpellier, France
3 Groupe Analyse du Mouvement, Dijon, France
Background. This investigation sought to characterise the oxygen uptake (V.O2) off-transient kinetics from severe exercise and to clarify discrepancies between on- and off-transient kinetics for V.O2 seen in humans.
Methods. Eleven competitive endurance athletes underwent treadmill running until exhaustion at work-rates corresponding to the speed that elicited ~95% of maximal V.O2. Gas exchange variables were determined breath-by-breath. Computerised non-linear regression techniques were used to fit the V.O2 on- and off-transient kinetics. A 3-exponential model described the V.O2 on-transient. V.O2 off-transient was analysed to each response time course using 3 different models: a single-exponential model for the entire period and 2 3-exponential models where exponential terms starting either together after a common time delay or after independent time delays.
Results. Both 3-exponential models provided an excellent fit (r2>0.90) to the off-transient data. Compared with on-transient, V.O2 off-transient kinetics was associated with a slower primary phase (time constant: 16±4 vs 39±13 sec, p<0.01) but was similar both in time delay and amplitude.
Conclusions. These data indicate that there is no general symmetry between the exercise and recovery kinetics for V.O2 because the response of the primary phase of V.O2 off-transient resolves to a greater time constant, reflecting altered tissue metabolism. However, the mechanism(s) for the slow component is slow both in developing and to recover within the severe exercise domain.