A 100 miler needs more than sports drinks to stop bonking. But in general I look for an Isotonic supplement for the water bottle that I like the taste of. And I also carry some extra powder in the pockets in individual sachets to mix up extra. There are plenty around but some of them leave too much after taste after about the 6th bottle.

My own personal taste is for one called "Leppin" and I use the training formula in Fruit Burst flavour. I buy it in 2kg tubs and I go through about 2 tubs a year at £25 a tub so a lot of it does get used.