Influence of HIIT and MICT on the effects of "priming" exercise on oxygen uptake kinetics during moderate-intensity exercise in individuals with type 2 diabetes

N. Gildea (Lead / Corresponding author), A. McDermott, J. Rocha, A. Nevin, D. O'Shea, S. Green, M. Egana (Lead / Corresponding author)

Research output: Contribution to journalMeeting abstractpeer-review


The dynamic response of pulmonary oxygen uptake (τV̇O2) during transitions to moderate-intensity exercise is slowed in type 2 diabetes (T2D), partly owing to an impaired blood flow delivery to the active musculature [1]. A prior heavy-intensity warm-up or priming exercise (PE) bout accelerates τV̇O2p in T2D by an enhanced matching of O2 delivery to utilisation [2]. Given both
low-volume, high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) also accelerate τV̇O2 in T2D by similar mechanisms [3], the aim of this study was to assess the priming effects on the V̇O2 and muscle deoxygenation (i.e., deoxygenated haemoglobin and myoglobin, [HHb+Mb]) kinetics during moderate-intensity cycling before training and at weeks 3, 6, 9 and 12 of MICT and HIIT.
Individuals with T2D (mean ± SD: age 53 ± 10 yr, body mass index 29.8 ± 4.4 kg.m-2) were randomly assigned to MICT (n=10, 50 min of moderate-intensity cycling) or HIIT (n=9, 10 x 1 min cycling at high-intensity interspersed by 1 min of ‘unloaded’ cycling) or to a non-exercising control (CON) group (n=9). Exercising groups trained 3 times/week and every 3 weeks exercise intensity was adjusted. At each time point participants completed four transitions to moderate-intensity cycling. Two of these bouts were completed without priming exercise and two bouts were undertaken with prior high-intensity priming exercise. [HHb+Mb] kinetics were measured by near-infrared spectroscopy at the vastus lateralis muscle. The local matching of O2 delivery to O2 utilisation was assessed by the Δ[HHb+Mb]/ΔV̇ O2 ratio (20-120s). Time point analysis of V̇ O2 and [HHb+Mb] responses were
performed using a two-way ANOVA with repeated-measures, and post-hoc Tukey tests performed when significant differences were returned.
At week 0, PE significantly (P<0.05) reduced τV̇O2 in all 3 groups, (MICT: from 44 ± 12 to 32 ± 5 s; HIIT: from 42 ± 8 to 32 ± 4 s; CON from 43 ± 7 to 31 ± 5 s). However, after 3 weeks of both HIIT and MICT, PE no longer had an effect on τV̇O2, but continued to significantly (P<0.05) reduce τV̇O2 in the CON group. The dynamic response of muscle deoxygenation was not affected by PE or training. Consequently, the Δ[HHb + Mb]/ΔV̇O2 ratio was significantly (P<0.05)reduced with PE at week 0 in all 3 groups, but while this PE-induced reduction was maintained at all time points in the CON group, it was not apparent (P>0.05) beyond the third week of the intervention in the exercising groups.
The accelerated V̇O2 kinetics responses consequent to both MICT and HIIT in T2D were likely attributed to rapid training-adaptations facilitating a better matching of O2 delivery to utilisation, and as such, beyond the third week of training the priming effect was negated.
Original languageEnglish
Article numberA 03-18
Pages (from-to)376-377
Number of pages2
JournalActa Physiologica
Issue numberS725
Early online date12 Sept 2022
Publication statusPublished - 30 Sept 2022
EventEurophysiology 2022 - Tivoli Congress Center, Copenhagen, Denmark
Duration: 16 Sept 202218 Sept 2022


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