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Medicine & Science in Sports & Exercise:
doi: 10.1249/MSS.0b013e3181d1fdb3
Clinical Sciences

Glycemic Status Affects Cardiopulmonary Exercise Response in Athletes with Type I Diabetes

BALDI, JAMES C.1; CASSUTO, NICHOLAS A.2; FOXX-LUPO, WILLIAM T.2; WHEATLEY, COURTNEY M.2; SNYDER, ERIC M.2

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Abstract

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 (HbA1c) < 7%, n = 5) and high-HbA1c (HbA1c > 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, HbA1c was lower in the low-HbA1c versus high-HbA1c group (6.5 ± 0.3 vs 7.8 ± 0.4, respectively; P < 0.05), but training volume was not different. At rest, the low-HbA1c group had greater cardiac output and lower systemic vascular resistance than the high-HbA1c group, and all pulmonary function measurements were greater in the low-HbA1c group (P < 0.05). During peak exercise, the V˙O2, workload, HR, stroke volume, and cardiac output were greater in the low-HbA1c versus the high-HbA1c group (P < 0.05). In addition, all indices of pulmonary function were higher in the low-HbA1c group (P < 0.05). Finally, within the subjects with diabetes, there was a weak inverse correlation between HbA1c and exercise training volume (r2 = −0.352) and stroke volume (r2 = −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.

©2010The American College of Sports Medicine

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