Running a marathon with new shoes is a big mistake, and grabbing a few gels and drinking when you feel like it in training is not specific enough to optimally prepare you for race day. This haphazard approach to marathon nutrition usually results in cramps, bonking and bathroom issues.
You need to experiment with how your body reacts to the different flavors and consistency of gels and sports drinks, changing weather conditions (you’ll need to drink more on hot days, which if not practiced, can result in bloating and cramping), and how far apart your stomach can handle different amounts of fuel and fluids.
Finding the right recipe takes time and practice.
Dott.ssa Annalisa Faè R&D ProAction