During exercise, particularly endurance exercise that is going to last longer than 90 minutes, research supports the ingestion of some carbohydrates to refuel the glycogen stores in your muscles and liver for optimum performance. The range is about 30g to 60g per hour depending on the duration and intensity of the activity (amongst other factors). But, should you eat or drink these carbs?
Either form will work, but ultimately, it may come down to what your preference is. Quite a few studies have researched whether liquid carbohydrates or solid carbohydrates are better absorbed by the body during exercise. The more pure the carbohydrate is, meaning the less it is mixed with proteins or fats, it doesn’t matter whether it’s solid or liquid, the rate at which it affects the body’s glucose levels, oxidation rates and performance levels is about the same. There is a caveat though, if you are going to rely on solid carbohydrate forms, you MUST be hydrating as well.
When fats or proteins are contained within a solid carbohydrate form (for example a bar), then you start seeing a difference between the digestion rate of this form vs. a liquid form. This is because it takes longer for the body to break down fats and proteins, so it delays the carbohydrates in the process as well. If you are experiencing a blood sugar drop, then a liquid carbohydrate would be best to increase that glucose level more rapidly. Or, if you’re trying to avoid hypoglycemia, then insuring that your nutrient sources are digested more slowly may be important to you.
The most important factor in all of this is how your GI tract responds. It’s widely known that endurance exercise and GI problems tend to go hand-in-hand. Bill Rodgers, a marathon king, even quipped that “more marathons are won or lost in the porta-toilets than at the dinner table.” Paula Radcliffe, another marathon phenom even had to relieve some tummy troubles during a race on the side of the road. Gut problems aren’t limited to just runners, cyclists, swimmers and any other forms of long duration endurance activities are all at risk for GI problems.
Find what works best for you that is easier on your gut. Varying your carbs is usually helpful – that means mixing in some fruit sugars with your rice sugars. Perhaps your stomach does better with only liquids, so you don’t feel like you have a brick of food sitting in your gut. You can try gels, though some say that brings that “sloshing” feeling. Or, maybe a solid bar is what you need to insure moderate glucose levels. Training is as much about miles and hours as it is about nutrition, so make sure you train your gut as well as your muscles!