During long distance endurance events such as an Ironman, Half Ironman, ultra marathon, or marathon our bodies will burn far more calories than we are capable of consuming. Take in too few calories and you’re going to hit the wall and bonk. Take in too many calories and you could be sidelined with gastrointestinal distress(stomach and intestine issues). You need to find a balance and rely on this plan come race day.
What can we absorb during endurance activities? Research tells us that our bodies can process 30 – 60 grams of carbohydrates per hour at a moderate intensity (very wide range because everyone is different). This amounts to a calorie range of 120 – 240 calories per hour (4 calories per gram of carbohydrate).
If you are using liquid calories, research shows that a 6-8% carbohydrate combination is ideal for stomach emptying (reducing the chance of gastrointestinal distress) The carbohydrate percentage is based on grams of carbohydrates:100ml of liquid. So let’s say you are drinking one water bottle per hour and let’s also assume that this fluid contains 18 ounces and 140 calories of carbohydrates. This amounts to 532 ml of fluid and 35 grams of carbohydrates (4 calories per gram). So, our drink combination would be 35 grams/532 ml = 6.5% carbohydrate solution. This would probably work for most people. However, let’s say you also ingest a portion of Cliff Bar or Power Bar containing 200 calories that hour. You would still have to factor this into your total consumption. Instead of 140 total calories you now have 340 calories, taking your carbohydrate concentration to 16%. If you repeat this hour after hour, you may run into trouble.
Personally, I treat my calorie needs and hydration needs as two separate entities. For hydration I only use water and for my calorie and electrolyte needs I use E-Gel. Let’s say that it’s a really hot day. Although my calorie needs will remain about the same, I’ll have to drink more water to stay hydrated. If I depended on a carbohydrate drink for my fluid needs, then I would risk the chance of exceeding what my body is capable of processing (calorie-wise) and potentially go into gastrointestinal distress.
Other Factors to Consider
First, each sport will influence how many calories you process. Running for example, creates a bigger challenge when trying to ingest calories since you have the repetitive pounding to jar things up a bit. Cycling creates less of an issue. So, you need to treat your calorie intake different for each sport. Second, dehydration significantly contributes to inadequate stomach emptying. Third, the type of carbohydrate (monosaccharide, disaccharide, polysaccharide) will impact how quickly they enter and leave the stomach. Fourth, adding fat or protein will also slow down your absorption rate. Finally, your intensity will impact your ability to absorb the amount of calories you ingest.
Don’t let the lack of a nutrition and hydration plan on race day be your downfall. Practice your race day plan during training so that you approach the start line with confidence, knowing that your rate of intake has been perfected. If you wait until race day to test out your plan, you are taking a big risk.
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One of the big factors in long distance racing is metabolic efficiency, your bodies ability to effectively utilize it’s available fuel as energy. Metabolically efficient athletes have taught their body how to utilize a larger percentage of fat for fuel. Let me explain this one. It’s impossible to consume even half the amount of calories you burn during competition. If your body becomes metabolically efficient at using the stored fat in your body for fuel, then you are less dependent on supplemental calories during competition which reduces the likelihood of GI distress. GI distress occurs when your stomach is not able to process the calories you are ingesting. This can be due to too many calories, too high of an intensity, or in most cases a little of both. In addition to an increased chance of GI distress, athletes who are not metabolically efficient face a much harder bonk when they are short of calories. Ideally you want to teach your body to depend on as little as possible so that GI distress is avoided. Typically, GI distress is a problem for athletes who need to depend on many more outside calories for fuel. This will ruin a race.
So how do you become metabolically efficient?
In the early season many of your long workouts need to be at a pace so that you are not pressing. At rest your body is always burring a combination of fat and carbohydrates for fuel. As you exercise and as your intensity increases, your body begins to burn a larger proportion of carbohydrates for fuel and less fat. Eventually, this inverse proportion of available fuel will switch entirely to carbohydrates. Working out at a lower intensity will keep the preferred fuel source dipping into the fat stores(which we have a nearly unlimited supply of) and less dependent on carbohydrates. You will also have to supplement less during your workout to replace lost fuel since you are depending on fat and not just carbohydrates. Furthermore, limiting your intake of carbohydrates during your workout teaches your body to rely on fat stores for fuel and your body will begin to adapt to utilize more fat, thereby becoming more efficient. Going too hard during a workout will make this adaptation impossible. Yes, you will get faster and yes you will develop more power, but you will not be metabolically efficient, which will come back to bite you when competing in events lasting more than 4 hours..and even more so when the event reaches the 8 plus hour range. DOn’t get me wrong. There is a time for hard intense workouts, but make sure all of your workouts are not of this nature
So the purpose of the early part of the season is to a)teach your body to become more efficient at utilizing fat for fuel, b)to teach the body to utilize oxygen more efficiently(at the cellular level), and c)to prepare itself for the increased workload (higher intensity. ie. intervals and vo2 tempos)later in the year. Remember, most workouts should reflect these early season goals. Ignoring this can mean limited gains later on down the road.
As you get closer to your goal race, its important to begin to transition to a higher intensity workout. What good is it to be metabolically efficient if you are unable to push a faster pace in a race. Remember, this should be a transition from off season training race specific training. I typically like to take three or four months to do this.
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