Continuous Glucose Monitoring in Ultra Trail Running during Performance and Recovery

Ultra-trail running is a demanding sport that requires the integration of various physiological functions during prolonged exercise. Maintaining glycaemic homeostasis during these activities is crucial and influenced by multiple factors such as food intake, hormonal feedback, and individual characteristics, including training level. Continuous Glucose Monitoring (CGM) systems have emerged as a promising tool for monitoring blood glucose levels in real-time, offering potential benefits in optimizing nutritional supplementation and enhancing performance. However, limited research has been conducted on healthy athletes, especially in the context of trail running, which has gained popularity in recent years. This work presents preliminary results of blood glucose concentrations before, during, and after training sessions of three athletes participating in an ultra-trail camp. Data were collected using Abbott Freestyle Libre2 sensors, and glucose trends were analyzed using statistical and regression analyses. The findings indicate that all three subjects demonstrated normal glycaemic trends during fasting periods and exhibited good autoregulation of post-meal glucose spikes. Some instances of hypoglycaemia were observed after long-distance running workouts but quickly returned to normal levels. Interestingly, the analysis revealed divergent responses to exercise among the subjects, with one highly trained individual maintaining stable glucose levels while the less trained athletes experienced a gradual increase in glycaemia during the sessions. The study highlights the feasibility of CGM systems in this context, although their reliability appears to be limited to a few days. Further research in this field is warranted to determine the utility of CGM systems as a personalized tool for optimizing nutrition and training strategies in ultra-trail runners and to explore post-exercise glycaemic dynamics and compensatory strategies.