Influence Of “Priming” Exercise On Pulmonary Oxygen Uptake Kinetics During Heavy‐Intensity Cycle Exercise From An Elevated Baseline In Type 2 Diabetes.

Abstract

In healthy individuals phase II oxygen uptake (V̇ O2) kinetics (τ V̇ O2p) is slower when heavy‐intensity exercise is initiated from a moderate‐intensity exercise baseline (work‐to‐work) than unloaded cycling; but τ V̇ O2p is not enhanced when work‐to‐work exercise is preceded by a prior bout of heavy‐intensity priming exercise (PE). This negates an insufficient muscle O2 availability as the primary culprit in healthy individuals.PurposeGiven that type 2 diabetes (T2D) induces a lengthened τ V̇ O2p during unprimed submaximal exercise compared with healthy controls, which is attributed, at least in part, to limitations in O2 supply, the purpose of the study was to test the hypothesis that heavy‐intensity PE would subsequently accelerate τ V̇ O2p in T2D.MethodsSeven middle‐aged individuals with T2D (46 ± 8 yr) and 7 controls (ND) (41 ± 10 yr) performed four bouts of constant‐load, heavy‐intensity exercise each commencing from a baseline of moderate‐intensity exercise. Two of these work‐to‐work bouts were completed without PE and two bouts were undertaken preceded by PE. V̇O2 kinetics was calculated from continuously measured breath‐by‐breath V̇O2 data, whilst the rate of muscle deoxygenation (i.e., deoxygenated haemoglobin and myoglobin, HHb+Mb) was continuously measured by near‐infrared spectroscopy at the vastus lateralis muscle. Diabetes and priming comparisons were made using two‐way ANOVA with repeated measures.ResultsThe amplitude of the V̇O2 slow component was reduced (P < 0.05) in both groups following PE (T2D: from 0.13 ± 0.15 to 0.08 ± 0.10 l/min; ND: from 0.20 ± 0.18 to 0.12 ± 0.11 l/min). In addition, PE tended to reduce τ V̇ O2p during work‐to‐work cycling transitions in T2D (from 54 ± 14 to 42 ± 17 s) but not in ND (42 ± 11 vs. 41 ± 11 s), bringing the τ V̇ O2p in T2D on a par with their ND counterparts, in the absence of significant changes in the dynamic response of (HHb+Mb). It is likely inter‐individual variability in response precluded the attainment of statistical significance.ConclusionIn middle‐aged individuals with T2D, the enhanced V̇ O2 kinetics response was likely consequent to a priming‐induced increase in muscle blood flow and/or improved muscle perfusion to metabolic rate.Support or Funding InformationThis publication has emanated from research conducted with the financial support of the Health Research Board of Ireland (Grant No HRA_POR/2073/274)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.