Time-course of V̇o2 kinetics responses during moderate-intensity exercise subsequent to HIIT versus moderate-intensity continuous training in type 2 diabetes

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

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11 Citations (Scopus)


We assessed the time-course of changes in oxygen uptake (V̇O2) and muscle deoxygenation (i.e., deoxygenated hemoglobin and myoglobin, [HHb + Mb]) kinetics during transitions to moderate-intensity cycling following 12 wk of low-volume high-intensity interval training (HIIT) vs. moderate-intensity continuous training (MICT) in adults with type 2 diabetes (T2D). Participants were randomly assigned to MICT (n = 10, 50 min of moderate-intensity cycling), HIIT (n = 9, 10 × 1 min at ∼90% maximal heart rate), or nonexercising control (n = 9) groups. Exercising groups trained three times per week, and measurements were taken every 3 wk. [HHb + Mb] kinetics were measured by near-infrared spectroscopy at the vastus lateralis muscle. The local matching of O2 delivery to O2 utilization was assessed by the Δ[HHb + Mb]/ΔV̇O2 ratio. The pretraining time constant of the primary phase of of V̇O(τV̇O2p) decreased (P < 0.05) at wk 3 of training in both MICT (from 44 ± 12 to 32 ± 5 s) and HIIT (from 42 ± 8 to 32 ± 4 s) with no further changes thereafter, whereas no changes were reported in controls. The pretraining overall dynamic response of muscle deoxygenation (τ'[HHb + Mb]) was faster than τV̇O2p in all groups, resulting in Δ[HHb + Mb]/V̇O2p showing a transient "overshoot" relative to the subsequent steady-state level. After 3 wk, the Δ[HHb + Mb]/V̇O2p overshoot was eliminated only in the training groups, so that τ'[HHb + Mb] was not different to τV̇O2p in MICT and HIIT. The enhanced V̇O2 kinetics response consequent to both MICT and HIIT in T2D was likely attributed to a training-induced improvement in matching of O2 delivery to utilization.
NEW & NOTEWORTHY High-intensity interval training and moderate-intensity continuous training elicited faster pulmonary oxygen uptake (V̇O2) kinetics during moderate-intensity cycling within 3 wk of training with no further changes thereafter in individuals with type 2 diabetes. These adaptations were accompanied by unaltered near-infrared spectroscopy-derived muscle deoxygenation (i.e. deoxygenated hemoglobin and myoglobin concentration, [HHb+Mb]) kinetics and transiently reduced Δ[HHb+Mb]-to-ΔV̇O2 ratio, suggesting an enhanced blood flow distribution within the active muscles subsequent to both training interventions.
Original languageEnglish
Pages (from-to)1646-1659
Number of pages14
JournalJournal of Applied Physiology
Issue number6
Publication statusPublished - 1 Jun 2021


  • cycling
  • exercise tolerance
  • muscle oxygenation
  • near-infrared spectroscopy
  • oxygen extraction


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