Nevertheless, while the accomplishment of this ratio could induce these benefits and reduce the energy deficit it is unknown whether athletes can tolerate high protein ingestion and perform high intensity exercise without gastro-intestinal disturbances. To avoid these problems, it is very recommendable that athletes perform a nutritional training before to the event ingesting small and frequent amounts Dibutyryl-cAMP of macronutrients and fluids during training sessions. This training may enhance the response of the digestive system during ultra-endurance events and

reduce the risk of gastro-intestinal distress during longer events in hard environment conditions. Acknowledgements The present study was funded by the National Institute of Physical Education (INEFC) and by the University of Zürich (Switzerland). The authors gratefully acknowledge the participation of the athletes in this study and the generous support of

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