title: Pancreatic β-cell function increases in a linear dose-response manner following exercise training in adults with prediabetes.
abstract: Although some studies suggest that a linear dose-response relationship exists between exercise and insulin sensitivity, the exercise dose required to enhance pancreatic β-cell function is unknown. Thirty-five older obese adults with prediabetes underwent a progressive 12-wk supervised exercise intervention (5 days/wk for 60 min at ~85% HRmax). Insulin and C-peptide responses to an OGTT were used to define the first- and second-phase disposition index (DI; β-cell function = glucose-stimulated insulin secretion × clamp-derived insulin sensitivity). Maximum oxygen consumption (Vo2max) and body composition (dual-energy X-ray absorptiometry and computed tomography) were also measured before and after the intervention. Exercise dose was computed using Vo2/heart-rate derived linear regression equations. Subjects expended 474.5 ± 8.8 kcal/session (2,372.5 ± 44.1 kcal/wk) during the intervention and lost ~8% body weight. Exercise increased first- and second-phase DI (P < 0.05), and these changes in DI were linearly related to exercise dose (DIfirst phase: r = 0.54, P < 0.001; DIsecond phase: r = 0.56, P = 0.0005). Enhanced DI was also associated with increased Vo2max (DIfirst phase: r = 0.36, P = 0.04; DIsecond phase: r = 0.41, P < 0.02) but not lower body fat (DIfirst phase: r = -0.21, P = 0.25; DIsecond phase: r = -0.30, P = 0.10) after training. Low baseline DI predicted an increase in DI after the intervention (DIfirst phase: r = -0.37; DIsecond phase: r = -0.41, each P < 0.04). Thus, exercise training plus weight loss increased pancreatic β-cell function in a linear dose-response manner in adults with prediabetes. Our data suggest that higher exercise doses (i.e., >2,000 kcal/wk) are necessary to enhance β-cell function in adults with poor insulin secretion capacity.
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio;
authors.forename: Steven K
authors.initials: SK
authors.lastname: Malin
authors.forename: Thomas P J
authors.initials: TP
authors.lastname: Solomon
authors.forename: Alecia
authors.initials: A
authors.lastname: Blaszczak
authors.forename: Stephen
authors.initials: S
authors.lastname: Finnegan
authors.forename: Julianne
authors.initials: J
authors.lastname: Filion
authors.forename: John P
authors.initials: JP
authors.lastname: Kirwan
mesh_terms: D000328:Adult; D000368:Aged; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D050417:Insulin-Secreting Cells / Q000502:physiology*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training / Q000379:methods; D011236:Prediabetic State / Q000503:physiopathology* / Q000628:therapy; D013997:Time Factors; D015431:Weight Loss / Q000502:physiology
keywords: aging; glucose intolerance; insulin resistance; obesity; type 2 diabetes
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