Time course adaptations in oxygen uptake kinetics during heavy-intensity exercise initiated from an elevated baseline subsequent to a 12 Week high-intensity interval or moderate-intensity continuous training in type 2 diabetes

Norita Gildea, Adam McDermott, Joel Rocha, Aaron Nevin, Donal O'Shea, Simon Green, Mikel Egana

Research output: Contribution to journalMeeting Abstract


The dynamic response of pulmonary oxygen uptake (V̇O2) at the onset of heavy- intensity exercise initiated from an elevated baseline (work-to-work) is constrained in middle-aged individuals with uncomplicated type 2 diabetes (T2D) (Gildea et al. 2018b) attributed to progressive limitations of O2 delivery and/or utilization. Both low-volume, high-intensity interval training (LVHIIT) and moderate-intensity continuous training (MICT) have been shown to be effective at accelerating V̇O2 kinetics during stepwise transitions from rest to moderate- (Gildea et al. 2018a), and heavy-intensity exercise (Nevin et al. 2018) in middle-aged individuals with T2D. However, the effects of such protocols on V̇O2 kinetics during heavy-intensity work-to-work cycling in individuals with T2D are unknown. Purpose: To assess the rates of adjustment of V̇O2p and muscle deoxygenation (i.e., deoxygenated haemoglobin and myoglobin, [HHb+Mb]) during the on-transition to heavy-intensity work-to-work cycling before training and at weeks 3, 6, 9 and 12 of MICT and LVHIIT. Methods: Twenty eight middle-aged individuals with T2D (17 men, 11 women; mean ± SD; age: 53 ± 10 yr, body mass index: 29.8 ± 4.4 kg.m-2) were randomly assigned to MICT (n=11, 50 min of moderate-intensity cycling), LVHIIT (n=8, 10 x 1 min cycling at ~90% maximal heart rate interspersed by 1 min of ‘unloaded’ cycling) or to a non-exercising control group (n=9). Exercising groups trained 3 times/week with intensity adjusted every 3 weeks. V̇O2 kinetics was calculated from continuously measured breath-by-breath V̇O2 data, and the rate of muscle deoxygenation continuously measured by near-infrared spectroscopy at the vastus lateralis muscle. Time point analysis of V̇O2 and [HHb+Mb] responses were performed using a two-way ANOVA with repeated-measures, and Tukey post-hoc tests performed when significant differences presented. Results: The pre-training time constant of the V̇O2 primary phase (τV̇O2P), the amplitude of the V̇O2 slow component (V̇O2scA) and V̇O2 mean response time (MRT), decreased (P<0.05) by a similar magnitude at wk 3 of training in both the MICT (48±10 to 30±8 s; 0.18±0.08 to 0.10±0.05 L.min-1 and 80±19 to 61±13 s, respectively) and LVHIIT (43±13 to 27±6 s; 0.20±0.07 to 0.14±0.06 L.min-1 and 73±17 to 60±13 s, respectively) groups with no further changes thereafter. No changes were reported in the control group. The pre-training parameter estimates of Δ[HHb+Mb] remained unchanged throughout the interventions. Conclusion: The enhanced V̇O2 kinetics responses during work-to-work transitions consequent to both MICT and LVHIIT in T2D is likely attributed to a combination of training-induced changes in skeletal muscle properties, motor unit recruitment patterns and improvements in O2 delivery relative to utilization during exercise.
Original languageEnglish
Article number830.8
JournalFASEB Journal
Issue number1 Suppl.
Publication statusPublished - 1 Apr 2019
EventExperimental Biology 2019 - Orange County Convention Center, Orlando, United States
Duration: 6 Apr 20199 Apr 2019


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