Impact of short-term exercise training intensity on -cell function in older obese adults with prediabetes

Malin SK, Francois ME, Eichner NZ, Gilbertson NM, Heiston EM, Fabris C, Breton M. Impact of short-term exercise training intensity on -cell function in older obese adults with prediabetes. J Appl Physiol 125: 1979 –1986, 2018. First published October 11, 2018; doi:10.1152/japplphysiol.00680.2018.—The effect of work-matched exercise intensity on -cell function is unknown in people with prediabetes before clinical weight loss. We determined if short-term moderate continuous (CONT) vs. high-intensity interval (INT) exercise increased -cell function. Thirty-one subjects (age: 61.4 2.5 yr; body mass index: 32.1 1.0 kg/m ² ) with prediabetes [American Diabetes Association criteria, 75-g oral glucose tolerance test (OGTT)] were randomized to work-matched CONT (70% HRpeak) or INT (3 min 90% HRpeak and 3 min 50% HRpeak) exercise for 60 min/day over 2 wk. A 75-g 2-h OGTT was conducted after an overnight fast, and plasma glucose, insulin, C-peptide, and free fatty acids were determined for calculations of skeletal muscle [oral minimal model (OMM)], hepatic (homeostatic model of insulin resistance), and adipose (Adipose-IR) insulin sensitivity. -Cell function was defined from glucose-stimulated insulin secretion (GSIS, deconvolution modeling) and the disposition index (DI). Glucagon-like polypeptide-1 [GLP-1(active)] and glucose-dependent insulinotropic polypeptide (GIP) were also measured during the OGTT, along with peak oxygen consumption and body composition. CONT and INT increased skeletal muscle- but not hepatic- or adipose-derived DI (P 0.05). Although both treatments tended to reduce fasting GLP-1(active) (P 0.08), early phase GLP-1(active) increased post-CONT and INT training (P 0.001). Interestingly, CONT exercise increased fasting GIP compared with decreases in INT (P 0.02). Early and total-phase skeletal muscle DI correlated with decreased total glucose area under the curve (r 0.52, P 0.002 and r 0.50, P 0.003, respectively). Independent of intensity, short-term training increased pancreatic function adjusted to skeletal muscle in relation to improved glucose tolerance in adults with prediabetes. Exercise also uniquely affected GIP and GLP-1(active). Further work is needed to elucidate the dose-dependent mechanism(s) by which exercise impacts glycemia.