731-P: Exercise Training Does Not Alter Resting Fatty Acid Mobilization from Adipose Tissue

Abstract

Excessive fatty acid (FA) mobilization from subcutaneous adipose tissue into systemic circulation underlies many metabolic health complications associated with obesity, such as insulin resistance. Exercise is often used to help treat and/or prevent insulin resistance, but the direct effects of exercise training (without weight loss) on systemic FA mobilization are unclear. The aim of this study was to determine the effect of both high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on FA rate of appearance (FA Ra) into systemic circulation and factors regulating FA mobilization from subcutaneous adipose tissue. 18 obese adults (33±3 kg•m-2) were randomized to 12 weeks (4 d/week) of either HIIT (10 x 1 min at 90% HRmax with 1 min recovery; n=8) or MICT (45 min at 70% HRmax; n=10), and were required to maintain bodyweight throughout. Resting FA Ra (13C palmitate dilution) and abdominal subcutaneous adipose tissue samples were collected in the overnight fasted state before and after training (72h following their final exercise session). The abundance of key lipolytic and lipid storage proteins in adipose tissue were measured via immunoblot. Aerobic fitness (VO2peak) increased ∼10% after training (P = 0.002), with no difference between HIIT and MICT. Body weight remained unchanged after training (HIIT: 98±12 vs. 98±13 kg, MICT: 101±12 vs. 100±13), as did fat mass (HIIT: 40±5 vs. 39±5 kg, MICT: 42±8 vs. 41±9). Training did not affect resting FA Ra in either HIIT (16.5±3.2 vs. 15.3±1.8 μmol•kg FM-1•min-1) or MICT (16.5±2.6 vs. 15.8±1.4 μmol•kg FM-1•min-1). In line with this finding, neither HIIT nor MICT altered adipose tissue abundance or phosphorylation-state of the lipolytic enzymes ATGL and HSL, or other factors involved in FA mobilization and storage in adipose tissue (e.g., GPAT, DGAT, CGI-58, G0S2, CD36). In summary, in the absence of weight loss, 12 weeks HIIT or MICT did not alter the regulation of resting FA mobilization from subcutaneous adipose tissue. Disclosure M.W. Schleh: None. B.J. Ryan: None. J.B. Gillen: None. P. Varshney: None. K. Foug: None. A. Ludzki: None. J.F. Horowitz: Research Support; Self; American Diabetes Association. Funding National Institutes of Health (R01DK077966, P30DK089503, T32DK007245); Canadian Institutes of Health Research (DFS146190)