Reduction of V-O2 slow component by priming exercise: novel mechanistic insights from time-resolved near-infrared spectroscopy

HANDLE Open Access

Abstract

Novel time-resolved near-infrared spectroscopy (TR-NIRS), with adipose tissue thickness correction, was used to test the hypotheses that heavy priming exercise reduces the (V˙O2) slow component (V˙O2SC) (1) by elevating microvascular [Hb] volume at multiple sites within the quadriceps femoris (2) rather than reducing the heterogeneity of muscle deoxygenation kinetics. Twelve subjects completed two 6-min bouts of heavy work rate exercise, separated by 6 min of unloaded cycling. Priming exercise induced faster overall (V˙O2) kinetics consequent to a substantial reduction in the (V˙O2SC)(0.27 ± 0.12 vs. 0.11 ± 0.09 L·min(-1), P < 0.05) with an unchanged primary (V˙O2) time constant. An increased baseline for the primed bout [total (Hb + Mb)] (197.5 ± 21.6 vs. 210.7 ± 22.5 μmol L-1, P < 0.01), reflecting increased microvascular [Hb] volume, correlated significantly with the (V˙O2SC) reduction. At multiple sites within the quadriceps femoris, priming exercise reduced the baseline and slowed the increase in [deoxy (Hb + Mb)]. Changes in the intersite coefficient of variation in the time delay and time constant of [deoxy (Hb + Mb)] during the second bout were not correlated with the (V˙O2SC) reduction. These results support a mechanistic link between priming exercise-induced increase in muscle [Hb] volume and the reduced (V˙O2SC) that serves to speed overall (V˙O2) kinetics. However, reduction in the heterogeneity of muscle deoxygenation kinetics does not appear to be an obligatory feature of the priming response.

Journal

Details 詳細情報について

  • CRID
    1050294045370404480
  • NII Article ID
    120006358590
  • ISSN
    2051817X
  • HANDLE
    20.500.14094/90004265
  • Text Lang
    en
  • Article Type
    journal article
  • Data Source
    • IRDB
    • CiNii Articles

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