Getting your nutrition and hydration right on a long hard climb isn’t that easy. There are some limiting hurdles that needs to be overcome and once you do, you can really improve your performance by a lot. Let’s examine these factors first and then come up with a solution one by one.
Carbs, carbs, carbs
Before reaching the summit of a climb there’s always the start at the foot of mountain. How you arrive at that foot is a crucial factor. Since riding uphill will demand a lot of energy from your body you will burn a lot of carbohydrates while climbing. The storage in your liver and muscles is limited and can be completely depleted in riding 60 to 90 minutes on the limit. Once this storage is (almost) gone you will need to switch back a lot of gears to an intensity that relies for the majority on burning fat. At this low intensity you will likely not overcome steep sections and will not reach the summit.
So what is important here is that you reach the start of a climb with these storages almost completely full. Be aware that your body can only digest 60 grams of carbohydrates every hour and about 90 up to 120 grams (in some studies) in the right combination of glucose and fructose (2:1). So if there is a long stage before reaching the climb, try to save energy and keep eating these amounts of carbs. Beware: eating enormous amounts of pasta or pancakes just hours before riding uphill makes your body constantly digest food while climbing. This digestion takes up energy that your body needs for overcoming gravity.
For hydration almost the opposite is true. Your body doesn’t really have a storage (like a camel) to save some fluid for a later moment. The only thing you need to do is to stay hydrated properly and you definitely must avoid to be dehydrated when you start climbing. So having a bottle with a carb solution about two to one hour prior to the effort will make sure you have your carb storage completed and you are properly hydrated.
During the climb
On the climb itself it can be hard to really eat solid food because of the high intensity. Still you need to try to uptake at least 60 grams of carbs every hour and preferably in the combination glucose/fructose 2:1. The best option to do that are gels and of course a carb solution in your bottles with around 25 to 40 grams of carbs per 500 ml. If you can reach the summit within the hour and you are sure you’ve started with a full storage you can eat less of course. However studies show that performance can be enhanced with even rinsing your mouth with a carb solution, because your body thinks new carbs are coming in. So even if the finish is near, performance can be enhanced with a carb solution and or a gel.
For drinking your body can also just uptake effectively around 500 to 750 ml fluid every hour. Still the sweat loss and the amount of fluid necessary for converting carbs into energy can be higher, especially on a climb with less cooling from the wind resistance. Make sure the fluid contains besides carbs also some electrolytes (salts). You will lose those with your sweat and they are essential for muscle contraction. So don’t drink too much and not just plain water. That can even make the electrolyte loss bigger resulting in overhydration in extreme cases. At the same time be aware that losing 4% of your body weight by sweat can cut your performance around 5% to 10%. You can’t out train such numbers so having a proper nutrition and hydration strategy is just key in becoming the King or Queen of the mountain!