Abstract
Low skeletal muscle capillarization is associated with impaired glucose tolerance (IGT); however, aerobic exercise training with weight loss (AEX + WL) increases skeletal muscle capillarization and improves glucose tolerance in adults with IGT. Given that the expression of angiogenic growth factors mediates skeletal muscle capillarization, we sought to determine whether angiogenic growth factor levels are associated with low capillarization in those with IGT versus normal glucose tolerance (NGT) or to the benefits of AEX + WL in both groups. Sixteen overweight or obese men 50-75 yr of age completed 6 mo of AEX + WL with oral glucose tolerance tests and vastus lateralis muscle biopsies for measurement of muscle vascular endothelial growth factor (VEGF), placental growth factor (PlGF), soluble fms-like tyrosine kinase receptor-1 (sFlt-1), and basic fibroblast growth factor (bFGF). At baseline, all growth factor levels were numerically lower in IGT than NGT, but these did not reach statistical significance (P = 0.06-0.33). Following AEX + WL, aerobic capacity [maximal oxygen consumption (V̇o(2max))] increased by 16%, whereas body weight and 120-min postprandial glucose levels decreased by 10% and 15%, respectively (P ≤ 0.001 for all). There was a main effect of AEX + WL to increase VEGF (0.095 ± 0.016 vs. 0.114 ± 0.018 ng/µg, P < 0.05), PlGF (0.004 ± 0.001 vs. 0.005 ± 0.001 ng/µg, P < 0.05), and sFlt-1 (0.216 ± 0.029 vs. 0.264 ± 0.036 ng/µg, P < 0.01), with overall increases driven by the IGT group. These results suggest that 6 mo of AEX + WL increases skeletal muscle angiogenic growth factor levels in obese older adults with IGT and NGT, which may contribute to our previous findings that AEX + WL increases capillarization to improve glucose tolerance in those with IGT.NEW & NOTEWORTHY Skeletal muscle capillarization is lower in adults with impaired glucose tolerance than normal controls. This may, in part, be attributable to differential expression of angiogenic growth factors in skeletal muscle. Using a 6-mo aerobic exercise intervention with ∼10% body weight loss (AEX + WL), we show that the expression of angiogenic growth factors tends to be lower in adults with impaired glucose tolerance compared with normal controls and that AEX + WL increased expression of angiogenic growth factors in all participants.