A Family History Of Type 2 Diabetes Does Not Limit Exercise Induced Improvement In Aerobic Fitness And Mitochondrial Function In Normoglycemic Sedentary Men

Abstract

A family history of type 2 diabetes (FH+) is considered a risk factor for the development of type 2 diabetes (T2D). However, it is unclear whether exercise induced improvements in insulin sensitivity (IS), maximal aerobic fitness (VO2max), and mitochondrial maximum ATP synthesis rate (ATPmax), are impacted by a FH+. PURPOSE: The purpose of this study was to 1) determine if normoglycemic, sedentary healthy individuals with FH+ have a lower IS, VO2max, and ATPmax compared to those without a family history of T2D (FH-) and 2) if exercise induced changes in IS, VO2max, and ATPmax is impeded in those with a FH+. METHODS: Fourteen normoglycemic sedentary males with (n=6; age=27.33 ± 2.65 years; BMI=26.48 ± 1.25 kg/m2) or without (n=8; age=26.63 ± 1.44 years, BMI=26.46 ± 0.57 kg/m2) FH were trained on a stationary bicycle for 30-55 minutes/session on alternate days of continuous and interval training for 13 days over 3 weeks. Non-exercising control (n=8; age=25.75 ± 1.85 years; BMI=24.38 ± 1.31 kg/m2) without a FH completed the same testing procedures at baseline and after 3 weeks. IS was assessed by hyperinsulinemic euglycemic clamp. ATPmax was measured by magnetic resonance spectroscopy, and VO2max was measured by a standardized graded exercise test. RESULTS: There were no differences in IS, ATPmax and VO2max between groups at baseline (one-way ANOVA all p>0.05). Three weeks of exercise increased VO2max only in FH- (Mean±SEM; Control 33.25 ± 1.68 to 32.66 ± 1.92 mL/kg/min, p=0.73; FH- 33.47 ± 1.85 to 35.24 ± 1.60 mL/kg/min, p=0.03; FH+ 29.96 ± 2.09 to 31.49 ± 2.07 mL/kg/min, p=0.14), increased ATPmax only in FH+ (Control 0.68 ± 0.04 to 0.69 ± 0.04 mM ATP/s, p=0.98; FH- 0.70 ± 0.05 to 0.73 ± 0.03 mM ATP/s, p=0.81; FH+ 0.61 ± 0.04 to 0.74 ± 0.05 mM ATP/s, p=0.02) but did not change IS in any group (Control 8.24 ± 0.93 to 7.00 ± 0.92 mg/kg/min, p=0.38; FH- 7.84 ± 0.82 to 8.42 ± 1.11 mg/kg/min, p=0.87; FH+ 5.39 ± 0.48 to 6.62 ± 0.83 mg/kg/min, p=0.51). CONCLUSION: Three weeks of combined endurance and interval exercise training improved ATPmax and VO2max overall, but did not change IS in normoglycemic sedentary individuals. FH+ does not seem to be a limiting factor for achieving exercise stimulated improvement in whole body aerobic fitness and mitochondrial function in a normoglycemic healthy sedentary population.