Priming exercise accelerates pulmonary oxygen uptake kinetics during “work-to-work” cycle exercise in middle-aged individuals with type 2 diabetes

Norita Gildea, Joel Rocha, Donal O'Shea, Simon Green, Mikel Egaña (Lead / Corresponding author)

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

Purpose: The time constant of phase II pulmonary oxygen uptake kinetics (V̇O2τp) is increased when high-intensity exercise is initiated from an elevated baseline (work-to-work). A high-intensity priming exercise (PE), which enhances muscle oxygen supply, does not reduce this prolonged V̇O2τp in healthy active individuals, likely because V̇O2τp is limited by metabolic inertia (rather than oxygen delivery) in these individuals. Since V̇O2τp is more influenced by oxygen delivery in type 2 diabetes (T2D), this study tested the hypothesis that PE would reduce V̇O2τp in T2D during work-to-work cycle exercise. 
Methods: Nine middle-aged individuals with T2D and nine controls (ND) performed four bouts of constant-load, high-intensity work-to-work transitions, each commencing from a baseline of moderate-intensity. Two bouts were completed without PE and two were preceded by PE. The rate of muscle deoxygenation ([HHb + Mb]) and surface integrated electromyography (iEMG) were measured at the right and left vastus lateralis, respectively.
Results: Subsequent to PE, V̇O2τp was reduced (P = 0.001) in T2D (from 59 ± 17 to 37 ± 20 s) but not (P = 0.24) in ND (44 ± 10 to 38 ± 7 s). The amplitude of the V̇O2 slow component (V̇O2τp2As) was reduced (P = 0.001) in both groups (T2D: 0.16 ± 0.09 to 0.11 ± 0.04 l/min; ND: 0.21 ± 0.13 to 0.13 ± 0.09 l/min). This was accompanied by a reduction in ΔiEMG from the onset of V̇O2 slow component to end-exercise in both groups (P < 0.001), while [HHb + Mb] kinetics remained unchanged.
Conclusions: PE accelerates V̇O2τp in T2D, likely by negating the O2 delivery limitation extant in the unprimed condition, and reduces the V̇O2As possibly due to changes in muscle fibre activation.
Original languageEnglish
Pages (from-to)409-423
Number of pages15
JournalEuropean Journal of Applied Physiology
Volume121
Issue number2
Early online date21 Oct 2020
DOIs
Publication statusPublished - 1 Feb 2021

Keywords

  • Near-infrared spectroscopy
  • oxygen extraction
  • Cycling
  • oxygen uptake slow component
  • electromyography

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