Effects of "priming" exercise on pulmonary O2 uptake and muscle deoxygenation kinetics during heavy-intensity cycle exercise in the supine and upright positions

Andrew M. Jones, Nicolas Berger, Daryl P. Wilkerson, Claire L. Roberts

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    51 Citations (Scopus)

    Abstract

    We hypothesized that the performance of prior heavy exercise would speed the phase 2 oxygen consumption (V̇O2) kinetics during subsequent heavy exercise in the supine position (where perfusion pressure might limit muscle O2 supply) but not in the upright position. Eight healthy men (mean ± SD age 24 ± 7 yr; body mass 75.0 ± 5.8 kg) completed a double-step test protocol involving two bouts of 6 min of heavy cycle exercise, separated by a 10-min recovery period, on two occasions in each of the upright and supine positions. Pulmonary O2 uptake was measured breath by breath and muscle oxygenation was assessed using near-infrared spectroscopy (NIRS). The NIRS data indicated that the performance of prior exercise resulted in hyperemia in both body positions. In the upright position, prior exercise had no significant effect on the time constant (τ) of the V̇O2 response in phase 2 (bout 1: 29 ± 10 vs. bout 2: 28 ± 4 s; P = 0.91) but reduced the amplitude of the V̇O2 slow component (bout 1: 0.45 ± 0.16 vs. bout 2: 0.22 ± 0.14 l/min; P = 0.006) during subsequent heavy exercise. In contrast, in the supine position, prior exercise resulted in a significant reduction in the phase 2 τ (bout 1: 38 ± 18 vs. bout 2: 24 ± 9 s; P = 0.03) but did not alter the amplitude of the V̇O2 slow component (bout 1: 0.40 ± 0.29 vs. bout 2: 0.41 ± 0.20 l/min; P = 0.86). These results suggest that the performance of prior heavy exercise enables a speeding of phase 2 V̇O2 kinetics during heavy exercise in the supine position, presumably by negating an O2 delivery limitation that was extant in the control condition, but not during upright exercise, where muscle O 2 supply was probably not limiting.

    Original languageEnglish
    Pages (from-to)1432-1441
    Number of pages10
    JournalJournal of Applied Physiology
    Volume101
    Issue number5
    DOIs
    Publication statusPublished - 24 Nov 2006

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