As you build mileage and run longer than 90 minutes, nutritional supplements and electrolytes become important in order to keep going. Energy for muscle contraction comes from stored carbohydrate, known as glycogen, and electrolytes are necessary to keep the body functioning normally. Sports drinks and run nutrition products assist running performance by limiting dehydration, providing electrolytes, and by supplying muscles with a quick source of energy.
Electrolytes serve a variety of functions in the body. Some of these functions include assisting with muscle contraction and the transmission of nerve impulses, of obvious importance to a runner. The more well-known electrolytes are calcium, potassium, sodium and magnesium. You lose many of these electrolytes in your sweat, but it is difficult to realise how much you are losing because you often can’t see them in hot, humid weather (compared to the white, crusty, sand-like substance all over your skin in dry conditions).
Your body stores carbohydrate in the form of glycogen in your muscles and liver. As you run, you convert glycogen into energy for muscle contraction. In general, the higher the intensity of the run, the higher the percentage of glycogen used. Conversely, the lower the intensity of the run, the higher the percentage of fat used. Some factors that contribute to run intensity are heart rate, run distance, heat, humidity and terrain.
You have a limited amount of stored glycogen available, and when you run out, you "hit the wall." Most runners have enough stored glycogen on board to get them through a half marathon without supplementation, but a full 26.2 is another story. Most runners will deplete their stored fuel before the finish line, typically around mile 18 or 20.
With that said, it's also important not to rely too heavily on supplementation.
Limiting the amount of sugar you ingest may be wise, because a recent study appears to indicate that the carbohydrates in sports products may actually limit some of the fitness adaptations you want your body to make to endurance training.
For example, sports drinks slow glycogen depletion (why we consume them), but researchers are now finding that some of the beneficial training adaptations we desire happen because of glycogen depletion. One benefit of depleting your glycogen stores is that this depletion enhances fat-burning capacity, an important fitness benefit. So, if you rely too heavily on sports products, you may actually blunt some of these adaptations.
My advice is moderation in all things. On your runs of 14 miles or less, try getting by on water and electrolytes. On runs over 14 miles, carry some run nutrition and/or sports drink with you so you are prepared. Take them if needed and experiment with how much and when you need to take them. If you notice feeling irritable, or your pace slows, or negative thoughts creep in, take some run nutrition or sports drink because these are all signs of low blood sugar.
For something other than Gu Energy or gels, try raisins and other dried fruits; such as, cherries or cranberries, which are very similar in composition to run supplements. You can also try using packets of honey or use run nutrition products sweetened with honey rather than sugar. Some runners also prefer using food like pretzels or mini peanut butter crackers.
Training runs are the time to experiment with what works best for you, so now is the time for you to do your homework. Keep a log and record what, when, and how much product you ingest along with your mileage. By race day, you should have a good feel for what you need to get you across the finish line without hitting the dreaded wall.
