Hi, the intestines have 2 transporters for carbohydrate, one for glucose and one for fructose. The glucose transporter can only cope with ~60g / hour glucose. By adding up to 30g fructose (any more and it may cause GI distress) the fructose transporter is utilised allowing upto 90g of carbohydrate to be processed per hour. As well as the advantage of more carbohydrate going to the working muscles, the mixture also improves water uptake compared to glucose alone.
If any more carbohydrate is ingested, there is a risk the transporters won't be able to process it and will therefore remain in the gut. Most of the early studies were performed by Roy Jentjens with his supervisor Asker Jeukendrup at the University of Birmingham, UK and are on http://www.pubmed.com
" onclick="window.open(this.href);return false;.
There is no benefit to consuming protein during exercise (see Breen, Tipton and Jeukendrup 2010(?)).
I buy glucose and fructose from the local health store and it is miles cheaper than High 5 etc. Just add your favourite no-added sugar cordial to the mix and off you go.