Vol 13, Issue 2

Effect of Acute High-intensity Interval Exercise on Whole-body Fat Oxidation and Subcutaneous Adipose Tissue Cell Signaling in Overweight Women

February 15, 2020 - By 

Authors

Hashim Islam, Queen’s University
Marysa M.W. Smith, Queen’s University
Trisha D. Scribbans, University of Manitoba
Emma McCrady, Queen’s University
Laura N. Castellani, University of Guelph
Matti D. Allen, Queen’s University
David C. Wright, University of Guelph
Craig A. Simpson, Queen’s University
Brendon J. Gurd, Queen’s University
International Journal of Exercise Science 13(2): 554-566, 2020.
DOI: 10.70252/FQEF4828

Abstract

Exercise-induced alterations in adipose tissue insulin and/or β-adrenergic signaling may contribute to increases in whole-body fat oxidation following acute exercise. Thus, we examined changes in insulin (Akt, AS160) and β-adrenergic (PKA) signaling proteins in subcutaneous adipose tissue and whole-body fat oxidation in overweight women following acute high-intensity interval exercise (HIIE). Overweight females completed two experimental sessions in a randomized order: 1) control (bed rest) and 2) HIIE (10 x 4 min running intervals at 90% HRmax, 2-min recovery). Subcutaneous abdominal adipose tissue biopsies were obtained from 10 participants before (pre-), immediately (0hr) after (post-), 2hr post-, and 4hr post-exercise. Plasma glucose and insulin levels were assessed in venous blood samples obtained at each biopsy time-point from a different group of 5 participants (BMI-matched to biopsy group). Fat oxidation rates were estimated using the respiratory exchange ratio (RER) in all participants using indirect calorimetry pre-, 2hr post-, and 4hr post-exercise. RER was decreased (p < 0.05) at 2hr post-exercise after HIIE (0.77 ± 0.04) compared to control (0.84 ± 0.04). Despite higher plasma glucose (p < 0.01) and insulin (p < 0.05) levels at 0hr post-exercise versus control, no significant interaction effects were observed for Akt or AS160 phosphorylation (p > 0.05). Phosphorylation of PKA substrates was unaltered in both conditions (p > 0.05). Collectively, altered β-adrenergic and insulin signaling in subcutaneous adnominal adipose tissue does not appear to explain increased whole-body fat oxidation following acute HIIE.

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