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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
Author(s) -
Gildea Norita,
McDermott Adam,
Rocha Joel,
Nevin Aaron,
O'Shea Donal,
Green Simon,
Egana Mikel
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.830.8
Subject(s) - cycling , intensity (physics) , interval training , high intensity interval training , medicine , heart rate , deoxygenation , cardiorespiratory fitness , vo2 max , cardiology , zoology , chemistry , biology , blood pressure , biochemistry , physics , quantum mechanics , archaeology , history , catalysis
The dynamic response of pulmonary oxygen uptake (VO 2 ) 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). Both low‐volume, high‐intensity interval training (LVHIIT) and moderate‐intensity continuous training (MICT) have been shown to be effective at accelerating V̇O 2 kinetics during stepwise transitions from rest to moderate‐, and heavy‐intensity exercise in middle‐aged individuals with T2D. Purpose To assess the rates of adjustment of V̇O 2 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 × 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. V̇O 2 kinetics was calculated from continuously measured breath‐by‐breath V̇O 2 data, and the rate of muscle deoxygenation continuously measured by near‐infrared spectroscopy at the vastus lateralis muscle. Time point analysis of V̇O 2 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 time constant of the V̇O 2 primary phase (τV̇O 2P ), the amplitude of the V̇O 2 slow component (V̇O 2sc A) and V̇O 2 mean response time (MRT), decreased ( P <0.05) by a similar magnitude at week 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 parameter estimates of Δ[HHb+Mb] remained unchanged throughout the interventions. Conclusion V̇O 2 kinetics during work‐to‐work transitions were greatly improved as a consequence of a time efficient LVHIIT in T2D within a short period of time. Whilst the underlying mechanisms appear less clear, likely attributions include training‐induced changes in skeletal muscle properties, motor unit recruitment patterns and improvements in O 2 delivery relative to utilization during exercise. Importantly, faster V̇O 2 kinetics are related to improvements in exercise tolerance that may increase the willingness to participate in exercise and thus result in an increased quality of life in this clinical population. Support or Funding Information This research was suppoerted by the Health Research Board of Ireland (Grant no HRA_POR/2073/274) This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .