Carbs and Fluids Fueling Tips for Triathletes

By Bob Seebohar | April 23, 2019, 4:52 p.m. (ET)

Triathlete fueling

I’ve written many race day nutrition articles over the past couple of decades and there is always one common theme no matter what the diet of the month is or distance of the race: every triathlete is different. So you don’t have to read a novel, I am going to limit my discussion about race day nutrition to only carbohydrate and fluid.

It’s not to say protein, fat and electrolytes are not important but I’ll save that for a future article.

Carbohydrate

Talk about the debate of the century ... and it’s not going away anytime soon. No sport dietitian, including myself, is a proponent of any type of “diet” that falls on one complete end of the continuum. A more balanced daily nutrition plan that is metabolically efficient is ideal for health and performance. Optimize blood sugar. That’s the goal.

During training and racing, we know the body needs carbohydrate, depending on the duration and intensity of effort. What we don’t know is the type, quantity and timing of carbohydrate intake. Why don’t we know? Because everyone is different. You may be a male, female, youth, beginner, professional, or may have a short-course or long-course focus. All of these factors contribute to what type, how much and how often you should consume carbohydrates.

Current hourly carbohydrate intake recommendations range from 30-90 grams (120-360 calories). Obviously, there is much confusion because this range is enormous. Where should a triathlete start? High or low? 

The amount of carbohydrates you eat throughout the day, relative to balancing blood sugar, will somewhat guide how many carbs you should supplement during training and races. I’m not going to get too far into this as it would take up at least three articles but if you are more interested in learning about that, check out my Metabolic Efficiency Training concept.

What should you do with carbs then? Ideally, you would have a metabolic efficiency test performed at a performance center. This test will not only tell you how efficient you are in using fat and carbohydrate through a series of exercise intensities but it will also provide you calorie burn numbers, which you can use to plan your nutrient timing strategy and not guess how many carbs you should eat during training and racing. Testing is the most accurate method of determining your hourly carbohydrate needs.

However, if you don’t have access to testing, you can try to go about it the old fashioned way but keep in mind that this will not be as accurate as testing. I recommend starting your hourly carbohydrate intake experiment on the low end during some two and a half to three-hour or longer training sessions. Note what your energy levels do during training, how your power or pace is affected and if your gut responds positively or negatively to the carbohydrate load that it is receiving. It’s a bit of an experiment, which is why you want to start this months before your competitive season, if possible.

Once you find a happy place for hourly carbohydrate consumption, stick with it. If you are brave and you want to take a few digestive chances, go ahead and slightly increase your intake of carbohydrate intake by 5-10 grams per hour during training sessions that are over three hours. Eventually, you will reach your carbohydrate ceiling which will be the point where your digestive tract will not be happy with you, if you know what I mean.

What about short course racing and training that may last under two and a half to three-hours? Usually, this type of training and racing will be at higher intensities and thus, you will use more carbohydrate as energy. Thus, you think you need to eat more but the opposite is usually true. Shorter duration, higher intensity exercise usually leads to a decreased digestive response so the more carbs you feed, the more risk of gastrointestinal issues.

Aim to consume 10 - 30 grams per hour for anything less than 3 hours in duration. If the training session is aerobic and less than 2 hours, you will likely not need any calories at all. A small snack or meal will suffice.

Fluid

Due to differing sweat and gastric emptying rates, the level of dehydration before beginning training sessions and races, sweat sodium concentration, and gender, it really is best to do a bit of experimenting months in advance with sweat rate measurements and fluid intake prior to race season.

The gut can safely process about 24 - 32 ounces of fluid per hour. Individual sweat rates can vary so the goal is not to try to fully replace your hourly fluid losses, especially if you are a heavy sweater and lose more than 32 ounces per hour. That would be disastrous for the gut! The goal is to enter a workout or race as hydrated as possible and maintain a frequent hydration plan throughout. How do you do this? It may be obvious but emphasizing your daily hydration plan is absolutely crucial. If you are well along the dehydrated path prior to a workout or race, there is really not much you can do once you begin except for damage control. The first step in your plan is to be diligent with staying hydrated each day.

Water is a great beverage to consume daily with meals and snacks, but during training and racing, you will likely need to add some electrolytes. Look for an electrolyte option that provides the “fab 5”— sodium, chloride, potassium, calcium and magnesium. In terms of quantities, well, that is going to be another experiment for you since every triathlete differs in their electrolyte losses. If you have the option of having a sweat sodium concentration test, that would be ideal as it will provide much more accurate information relative to your hourly electrolyte needs.

However, if you can’t get this testing done, time to roll up the sleeves and experiment a bit. Similar to my hourly carbohydrate recommendations, start at a lower end of sodium replacement, around 200 - 400 milligrams per hour. If you feel lightheaded, more fatigued or lethargic during the workout or your performance markers (power, pace, heart rate) are a bit off, try adding an additional 100 milligrams of sodium per hour. Don’t forget that these recommendations will certainly change as it becomes warmer outside! What about the other electrolytes you say? While they are important to round out the electrolyte mix, sodium is by far the most important as it is the mineral lost most in sweat.

There you have it! Carbs and fluid. Two of the most confusing yet important nutrients that a triathlete needs to focus on as race season approaches! With a bit of experimentation and testing, you can be on your way to a solid carbohydrate and fluid replacement plan for all of your training and racing adventures this summer. Have fun out there!

Bob Seebohar, MS, RD, CSSD, CSCS, METS II, 2008 Olympic Team USA and Triathlon Team Sport Dietitian and Exercise Physiologist, is the owner of eNRG Performance and co-owner of Birota Foods. He’s a nutrition coach, USAT Level III Coach and accomplished endurance athlete who walks the walk and talks the talk. Find out more about Bob at www.enrgperformance.com and more about his metabolically efficient Smart Cocoa and Smart Coconut Creamer products at www.birotafoods.com.