Scientific product rationalInternational Olympic Committee: “…To achieve the relatively high rates of intake (up to 90 g/h) needed to optimize performance in events lasting longer than 3 hours, athletes should practice consuming carbohydrates during training to develop an individual strategy, and should make use of sports foods and drinks containing carbohydrate combinations that will maximize absorption from the gut and minimize GI disturbance.“
Exercise over 1 hour requires 30-60 g.
However, exercise over 2,5 h you may utilize 90 g per hour. (Jeukendrup, D.S. Rowlands)