Use Of Continuous Glucose Monitoring During Experimentally-induced Acute Low Energy Availability In Female Endurance Runners

Use of Continuous Glucose Monitoring (CGM) During Experimentally-Induced Acute Low Energy Availability in Female Endurance Runners Anna Morozov, Trisha Sterringer, D. Enette Larson-Meyer,Virginia Tech, Blacksburg, VA. Department of Human, Nutrition, Foods, and ExerciseEndurance runners have a high probability of experiencing low energy availability (LEA). Preliminary evidence suggests that blood glucose concentration decreases in response to acute energy deficiency in exercising eumenorrheic women. Blood glucose (BG) monitoring tools, such as the continuous glucose monitor (CGM), could be used as an early detection device for LEA risk in athletes. PURPOSE: Characterize changes in BG over the course of 5 days in experimentally-induced LEA in female runners. METHODS: Nine recreational runners (26 ± 4 yr; 65.7 ± 8.9 kg; 29.4 ± 5.5 %body fat; VO2max, 43.4 ± 7.9 ml/kg/min; mean ± SD) completed a 5-day experimental condition of LEA (15 kcal/kg/FFM/day) achieved by a combination of dietary restriction and treadmill running at 65% VO2max. BG concentration was monitored every 5 min across the 5 experimental days using a CGM (Freestyle Libre Pro, Abbott). Data were analyzed using repeated measures analysis of variance; post hoc comparisons were performed using paired t-tests. RESULTS: Five days of LEA resulted in significant increases in average BG concentration (time-effect, P = 0.015), which was increased on day 2 (86.3 ± 12.3 mg/dL, P = 0.16), day 3 (87.4 ± 9.9 mg/dL, P = 0.034), day 4 (86.3 ± 9.1 mg/dL, P = 0.096), and day 5 (89.8 ± 7.8 mg/dL, P = 0.011) compared to day 1 (82.7 ± 9.2 mg/dL). However, there were no differences in time spent ‘within target’ (P = 0.95), ‘below target’ (P = 0.178), or ‘above target’ (P = 0.223) ranges. CONCLUSION: Although BG concentration has previously been found to decrease in LEA conditions, our results suggest that 5 days of experimentally-induced LEA in female runners progressively increases average BG. These changes are likely due to alterations in glucose production versus utilization that are driven by decreased insulin and/or increased BG counterregulatory hormones. This data also emphasizes the potential usefulness of CGMs to gain further insight on BG patterns during conditions of LEA.