"Guidelines 10 years ago stated that carbohydrate intake during exercise should be 30-60 grams per hour, this developed to intakes of 90 g/h in some situations, but recently a paper was published that suggested intakes of 120 g/h in mountain marathon runners."
"Runners find it hard to ingest carbohydrate during running, perhaps because they are not used to it. Studies show they could benefit from higher intakes."
I recommend that on runs longer than 2 hours, athletes fuel every 30 minutes with 25-30g of carbs at each feeding and working up from there as tolerated for events longer than 6 hours especially.
Increased carbohydrate intake during exercise not only leads to better performance but also leads to reduced muscle damage.
To prepare for your next run of over 2 hours, take a look at your running fuel and count the number of carbs you normally have, is it enough? Is it time to start adding fuel to your long runs for better performance?
Need some inspiration in the kitchen? Here is a great book for food on the go.
Here is a sample recipe from the book.