Aerobic exercise training improves blood glucose homeostasis in healthy older adults

The present study assessed the effects of aerobic exercise training (AER) on blood glucose regulation in healthy older adults, and whether these effects depend on baseline glucose regulation. Thirty-four healthy older adults (71 ± 4 y) were randomized to perform 8 weeks of AER (n = 17) or no exercise (CON, n = 17). A five-point oral glucose tolerance test was performed at baseline and post-intervention to assess plasma glucose and insulin concentrations. Glucose regulation was assessed by Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), Hepatic Insulin Resistance Index (HIRI), Muscle Insulin Sensitivity Index (MISI), and Matsuda index. Two-factor repeated measures ANOVAs were performed on the full cohort and on a subgroup (CON: n = 10, AER: n = 9) with Matsuda index ≤5. Full Cohort Analyses: a significant interaction effect (P < 0.05) was observed only for HIRI (P = 0.025), which worsened in CON (+151 ± 232, P = 0.016) but not AER (-32 ± 221, P = 0.557). Subgroup Analyses: significant interaction effects were observed for hepatic glucose regulation (P ≤ 0.013), which worsened in CON (HOMA-IR: +0.5 ± 0.6, P = 0.085; HIRI: +249 ± 253, P = 0.006), but tended to improve in AER (HOMA-IR: -0.6 ± 1.2, P = 0.051; HIRI: -133 ± 241, P = 0.125). A significant interaction effect was observed for Matsuda index (P = 0.004), which increased in AER (from 3.2 ± 1.1 to 4.8 ± 2.1, P = 0.002), but remained unchanged in CON (from 3.8 ± 0.9 to 3.5 ± 1.4, P = 0.401). A trend toward an interaction effect was noted for MISI (AER: from 0.12 ± 0.07 to 0.19 ± 0.16; CON: from 0.18 ± 0.11 to 0.16 ± 0.06, P = 0.082). Aerobic exercise training improves blood glucose regulation in healthy older adults, with greater impact in those with a more compromised blood glucose regulation (based on Matsuda index ≤5).