1127-OR: Effects of Carbohydrate Intake on Cycling Endurance and Neuromuscular Fatigue in Adults with and without Type 1 Diabetes (T1D)

Introduction and Objective: Carbohydrates (CHO) during exercise increase blood glucose (BG) and improve exercise endurance in adults without diabetes. Whether these benefits extend to T1D is unclear. We examined cycling endurance and peripheral and central components of neuromuscular fatigue under CHO and placebo (PLA) conditions in T1D and matched controls (CON). Methods: In a blinded crossover design, participants cycled to task failure at ~60% peak power with CHO (60 g/h) or PLA. Neuromuscular function was evaluated every 20 min and at task failure on a dynamometer using maximal voluntary contraction (MVC) and electrically evoked knee extensor responses to quantify peripheral and central (% voluntary activation) fatigue. Results: Nine T1D and CON (33% female, age 26±11 years, BMI 25.0±3.6 kg/m²) completed all sessions. While CHO intake increased BG in T1D (115±27 vs 101±36 mg/dL) and CON (97±13 vs 83±14 mg/dL), time to task failure was lower in T1D with CHO (−7±14 min, p=.60) and PLA (−22±14 min, p=.13) conditions. During PLA only in the T1D group, exercise was terminated prior to task failure 6 of 9 times due to hypoglycemia. MVC and peripheral fatigue did not differ between groups or conditions at any timepoint (FIG). However, voluntary activation was consistently lower in T1D (p=.02), suggesting higher central fatigue versus CON. Conclusion: CHO limits hypoglycemia during prolonged cycling in T1D, and confers similar performance benefits relative to CON. Disclosure L.V. Turner: None. A.J. Richards: None. A.J. Cheng: None. M. Riddell: Research Support; Ended; Dexcom, Inc. Speaker's Bureau; Current; Dexcom, Inc., Novo Nordisk. Consultant; Current; Jaeb Center for Health Research. Advisory Panel; Current; Zucara Therapeutics.