Research article - (2007)06, 526 - 531
No Influence of Hypoxia on Coordination Between Respiratory and Locomotor Rhythms During Rowing at Moderate Intensity
Nicolas Fabre1,3,, Stéphane Perrey2, Philippe Passelergue3, Jean-Denis Rouillon1
1Laboratoire des Sciences du Sport, Besançon, France
2EA 2991 Efficience et Déficience Motrices, UFR STAPS, Montpellier, France
3Laboratoire d’Analyse de la Performance Sportive, Université de Pau, Département STAPS, Tarbes, France

Nicolas Fabre
✉ Laboratoire d’Analyse de la Performance Sportive, Département STAPS, Université de Pau et des Pays de l’Adour, Quartier Bastillac, 65000 TARBES - France
Email: fabre.nicolas@tiscali.fr
Received: 02-08-2007 -- Accepted: 20-09-2007
Published (online): 01-12-2007

ABSTRACT

Besides neuro-mechanical constraints, chemical or metabolic stimuli have also been proposed to interfere with the coordination between respiratory and locomotor rhythms. In the light of the conflicting data observed in the literature, this study aimed to assess whether acute hypoxia modifies the degree of coordination between respiratory and locomotor rhythms during rowing exercises in order to investigate competitive interactions between neuro-mechanical (movement) and chemical (hypoxia) respiratory drives. Nine male healthy subjects performed one submaximal 6-min rowing exercise on a rowing ergometer in both normoxia (altitude: 304 m) and acute hypoxia (altitude: 2877 m). The exercise intensity was about 40 % and 35 % (for normoxia and hypoxia conditions, respectively) of the individual maximal power output measured during an incremental rowing test to volitional exhaustion carried out in normoxia. Metabolic rate and minute ventilation were continuously collected throughout exercise. Locomotor movement and breathing rhythms were continuously recorded and synchronized cycle-by-cycle. The degree of coordination was expressed as a percentage of breaths starting during the same phase of the locomotor cycle. For a same and a constant metabolic rate, acute hypoxia did not influence significantly the degree of coordination (mean ± SEM, normoxia: 20.0 ± 6.2 %, hypoxia: 21.3 ± 11.1 %, p > 0.05) while ventilation and breathing frequency were significantly greater in hypoxia. Our results may suggest that during rowing exercise at a moderate metabolic load, neuro-mechanical locomotion-linked respiratory stimuli appear “stronger ”than peripheral chemoreceptors- linked respiratory stimuli induced by hypoxia, in the context of our study.

Key words: Control of breathing, locomotor-respiratory coupling, neuro-mechanical entrainment, chemical drive

Key Points
  • Changes in breathing frequency and ventilation induced by altitude have no effect on the degree of coordination between locomotor and breathing rhythms during moderate rowing exercise.
  • During moderate rowing exercise in hypoxia, the neuro-mechanical drives still dominate over chemoreceptive stimuli.
  • These above statements have to be taken carefully because it might be quite different during activities where the coupling between locomotor and breathing rhythms is less constrained (e.g., running, cycling).








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