RISSANEN, A-P. E., H. O. TIKKANEN, A. S. KOPONEN, J. M. AHO, and J. E. PELTONEN. Central and Peripheral Cardiovascular Impairments Limit VO2peak in Type 1 Diabetes. Med. Sci. Sports Exerc., Vol. 47, No. 2, pp. 223-230, 2015. Purpose: Cardiovascular risk, predicted by peak O2 uptake (VO2peak), is increased in type 1 diabetes. We examined the contribution of central and peripheral mechanisms to VO2peak in physically active adults with type 1 diabetes. Methods: Seven men with type 1 diabetes and 10 healthy age-, anthropometry-, and physical activity-matched men performed incremental cycling exercise until volitional fatigue. Alveolar gas ex- change (turbine and mass spectrometry), cardiac function and systemic vascular resistance (impedance cardiography), and local active leg muscle deoxygenation and blood flow (near infrared spectroscopy) were monitored. Arterial-venous O2 difference was calculated (Fick principle). Blood volume (BV) (carbon monoxide rebreathing method) and glycemic control (glycosylated hemoglobin) were determined. Results: The group with diabetes had lower VO2peak than controls (47 T 5v s 56T 7m LImin j1 Ikg j1 fat-free mass, P G 0.05). At peak exercise, fat-free mass-adjusted stroke volume (SV) and cardiac output (CO) were lower and systemic vascular resistance was higher in the group with diabetes than those in controls (P G 0.05). Leg muscle blood flow was reduced independently of CO in the group with diabetes at peak exercise (P G 0.05), whereas arterial-venous O2 difference was similar in the groups throughout the exercise (P 9 0.05). The group with diabetes had lower relative BV than controls (P G 0.01), and BV correlated positively with peak SV and peak CO (P G 0.001). In the group with diabetes, peak SV and peak CO correlated (P G 0.05) and peak leg muscle blood flow tended to correlate (P = 0.070) inversely with glycosylated hemoglobin. Conclusions: Both central and peripheral cardiovascular impairments limit VO2peak in physically active adults with type 1 diabetes. Importantly, central limitations, and probably peripheral limitations as well, are asso
