title: Continuous glucose monitoring during a 100-km race: a case study in an elite ultramarathon runner.
abstract: The current case study intended to measure blood glucose fluctuation in 2 marathon runners during a 100-km race using a continuous glucose-monitoring system (CGMS) and investigate the relationship between glucose profile and change in running speed. Two experienced ultramarathon runners participated in this study. A CGMS glucose sensor was inserted into the subcutaneous abdominal tissue at 35 h before the 100-km race, and the glucose profile was monitored continuously until the end of the race. Race pace and energy intake during the race were recorded. Participants finished the race in 6h:51min:17s (runner A) and 8h:56min:04s (runner B), and the race-pace decrement ratios were 17.6% for runner A and 27.2% for runner B. The average relative intensity throughout the 100-km race was 89.9% ± 5.8% lactate threshold (LT) in runner A and 78.4% ± 8.6% LT in runner B. The total amount of carbohydrate intake during the race was 249 g and 366 g in runners A and B, respectively. Despite lower carbohydrate intake, runner A maintained a normal glucose level throughout the race, while runner B rapidly decreased blood glucose and became hypoglycemic after the 80-km point. These results suggest that elite ultramarathon runners may have the ability to prevent a large decrement in blood glucose level regardless of the amount of energy intake during the race to maintain higher relative running intensity.
authors.affiliation: Faculty of Health and Sport Science, University of Tsukuba, Tsukuba, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Sengoku
authors.forename: Kazuteru
authors.initials: K
authors.lastname: Nakamura
authors.forename: Hitomi
authors.initials: H
authors.lastname: Ogata
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Nabekura
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Nagasaka
authors.forename: Kumpei
authors.initials: K
authors.lastname: Tokuyama
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D015190:Blood Glucose Self-Monitoring; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004326:Drinking; D002149:Energy Intake; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology*; D014887:Weather
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates