Previously, it was reported that the blood glucose kinetics during incremental exercise was affected by training status. Nevertheless, the relationships between the blood glucose kinetics during incremental exercise and the long-distance running performance have not been examined longitudinally. Therefore, the purpose of this longitudinal case study was to examine these relationships. This study included one recreational male runner, who performed the incremental running test （at the 0th, 22nd, and 39th week） and the 2-km and 5-km performance test （at 1-2 weeks before the incremental running test）and participated in full marathon （at the 24th and 40th week）. We evaluated the relationship between variations of incremental running test parameters （expired gas, blood lactate, blood glucose）and variations in long-distance running performance （2-km, 5-km, full marathon）, and analyzed the participant's training volume and intensity for 39 weeks. During the incremental running test, compared with 0th week, the participant’s blood glucose level increased, and the relative intensity of the peak oxygen uptake and respiratory exchange ratio decreased. However, the blood lactate and blood glucose thresholds did not improve. The velocity of long-distance running increased, but the increase in the velocity during the marathon was higher than the increase in velocity during the 2-km and 5-km performance tests. These results suggest that, with regard to blood glucose parameters during incremental exercise, training might affect the rise in blood glucose level to a greater extent than the blood glucose threshold. Furthermore, the rise in the blood glucose level during incremental exercise is a more important factor for the evaluation of training parameters for long competitions, such as in full marathons.
