Abstract
BALDI, J. C., N. A. CASSUTO, W. T. FOXX-LUPO, C. M. WHEATLEY, and E. M. SNYDER. Glycemic Status Affects Cardiopulmonary Exercise Response in Athletes with Type I Diabetes. Med. Sci. Sports Exerc., Vol. 42, No. 8, pp. 1454-1459, 2010. Purpose: This study aimed to (a) examine the influence of type I diabetes on the cardiopulmonary exercise response in trained subjects and (b) determine whether glycemic control affects these responses. Methods: The cardiopulmonary responses to maximal incremental cycle ergometry were compared in 12 Ironman triathletes with type I diabetes and 10 age- and sex-matched control subjects without diabetes. Athletes with type I diabetes were then stratified into low-(glycosylated hemoglobin (HbA(1c)) < 7%, n = 5) and high-HbA(1c) (HbA(1c) > 7%, n = 7) groups for comparison. Cardiac output, stroke volume, arterial blood pressure, and calculated systemic vascular resistance along with airway function were measured at rest and during steady-state exercise. Results: During peak exercise HR, stroke volume and cardiac output were not different between the groups with and without diabetes; however, forced expiratory flow at 50% of the forced vital capacity was lower in subjects with diabetes (P < 0.05). Within the group with diabetes, HbA(1c) was lower in the low-HbA(1c) versus high-HbA(1c) group (6.5 +/- 0.3 vs 7.8 +/- 0.4, respectively; P < 0.05), but training volume was not different. At rest, the low-HbA(1c) group had greater cardiac output and lower systemic vascular resistance than the high-HbA(1c) group, and all pulmonary function measurements were greater in the low-HbA(1c) group (P < 0.05). During peak exercise, the (V)over dotO(2), workload, HR, stroke volume, and cardiac output were greater in the low-HbA(1c) versus the high-HbA(1c) group (P G 0.05). In addition, all indices of pulmonary function were higher in the low-HbA(1c) group (P < 0.05). Finally, within the subjects with diabetes, there was a weak inverse correlation between HbA(1c) and exercise training volume (r(2) = -0.352) and stroke volume (r(2) = -0.339). These data suggest that highly trained individuals with type I diabetes can achieve the same cardiopulmonary exercise responses as trained subjects without diabetes, but these responses are reduced by poor glycemic control.