Aug 17, 2016
On Course
Linda Samuels

Proper nutrition is needed to propel triathletes from swim, to bike, to run. Developing a dedicated fueling and hydration plan can start them on the right path.

This article first appeared in the July/August 2016 issue of Training & Conditioning.

Triathlete (tri-ath’lete): n. a person who doesn’t understand that one sport is enough.

This “definition” provides insight into the personalities of triathletes-they tend to be highly competitive, driven, and constantly searching for ways to boost their performance. Often, this quest for improvement leads them to take a close look at their fueling plan.

It’s said that nutrition is the fourth discipline of triathlon. As a performance dietitian who has specialized in triathlon nutrition for nearly 10 years, I’ve heard hundreds of athletes vent about how their fueling plan (or lack thereof) has impeded their race-day performance. They often want to know what new diet, supplement, or “super food” will make the difference and get them back on track. The reality, however, is that learning a few basic nutrition and hydration concepts and paying attention to how the body responds will transform athletic performance much more than any quick fix ever could.

The process is not difficult, but it takes some commitment from the triathlete. Undergoing a thorough assessment is a good place for them to start. Then, by dialing in on hydration needs, revamping their meal plan, and focusing on adequate fueling during races, they will be well on their way to improved performance.


Anytime a triathlete comes to me for nutritional advice, my first step is assessing their hydration plan. Guidelines from the American College of Sports Medicine state that loss of more than two to three percent of bodyweight in one workout should be prevented, and some triathletes can easily exceed this number.

To get an idea for how much fluid my clients lose during training, I have them complete a series of sweat rate tests (SRTs) when we start working together. They conduct separate tests for swimming, biking, and running, as it’s vital to know exactly how much fluid they lose in each stage. For instance, triathletes typically don’t think about how much they sweat while swimming, but if they ignore it, they can start the bike leg in a dehydrated state. Then on the bike, many don’t realize how much they perspire because the sweat evaporates in the wind.

The SRTs aren’t just a one-time thing, however. I instruct my triathlete clients to continue performing the tests over the course of a season to see how their sweat patterns are affected by changes in the weather. That way, they have a reference for what their sweat rate will be on any given day and can plan fluid intake accordingly.

Determining hydration needs can be especially tricky when working with salty sweaters, who exhibit a white, salty residue on their clothes and skin after exercise. Should these triathletes hydrate inadequately, they put themselves at risk for developing hyponatremia, or low serum sodium levels. Symptoms include confusion/disorientation, high blood pressure, nausea/vomiting, swollen hands and feet, wheezing, and bloated belly. Hyponatremia is especially dangerous during exercise, and the most severe cases can be fatal.

To prevent this condition from occurring, I have salty sweaters take a patch test when we start working together. The patch captures their sweat, which is then extracted and tested to measure how much sodium it contains. I use the results to ensure the triathlete meets their increased sodium needs during training, typically by consuming extra sports drinks and/or sodium supplements.

After obtaining all the necessary information on a client’s sweat patterns, I am able to properly formulate their hydration plan. Using an upcoming racecourse for reference, I look at their estimated bike speed and run pace to determine how often they should drink. For example, if there are going to be aid stations at one-mile intervals during the run, and the athlete runs nine-minute miles, they should drink every nine minutes in training to replicate what they’ll do on the course. The more triathletes practice their hydration schedule, the better prepared they will be for race day.


Once a triathlete’s hydration plan is squared away for training, I turn my attention to their dietary intake. If I had a dollar for every time a client said to me, “Just tell me what to eat!” I’d be rich. If only it were that simple!

When I first assess a triathlete’s nutritional status, I rarely have blood work to alert me of any nutrient deficiencies. So to get an idea of what they typically eat, I ask them to complete a three-day food log in relation to their training schedule. The logs allow me to assess the timing and type of macronutrients they consume and whether they have a balanced diet. I also check to see if they are eating three daily servings each of fruit, veggies, and dairy, which is a quick way to identify if their diet lacks certain vitamins and minerals.

If I find a triathlete is deficient in any macronutrients when reviewing their food logs, I ask them where and how they think they can add more in their diet. I’ve learned that giving them input into their revised food plan improves compliance.

One of the best ways to boost macronutrient intake is through pre- and post-workout snacks. Before training, I advise triathletes to eat a small snack of simple carbohydrates to “start their engines.” These should be portable and easily tolerated. Examples include a handful of pretzels, a couple of fig bars, a banana, or 12 ounces of a sports drink.

Many triathletes have reduced appetites following intense exercise, so they struggle with consuming the calories needed at this time. In these cases, I work with athletes to find ways of getting carbs and protein in a manner they can tolerate, such as a protein and fruit smoothie.

There are other athletes facing the opposite problem-their appetite increases after exercise. Adding protein and fiber-rich foods to their diet can provide the satiety they crave. If they are waking up at night with intense hunger following a late-night workout, we plan an additional evening snack with a protein source, such as cheese sticks and crackers.

Beyond macronutrient deficiency, other dietary issues for triathletes typically stem from their inexperience cooking for themselves. They might have a strong desire to eat better and enjoy eating healthy foods but falter because they don’t know how to meal plan, create a grocery list, or prepare a meal. This is where a little training can make a big difference. I often walk athletes through basic meal planning tips and help them prepare grocery lists. They also spend time with me in the kitchen learning cooking skills.

One very helpful resource for teaching triathletes how to properly plan meals has been Athlete’s Plates. Developed by the registered sports dietitians at the U.S. Olympic Training Centers and available on the Team USA website, this program explains how athletes should manage their food intake based on their training intensity. On easy training days, fruits and vegetables should comprise about half of their plates, with lean proteins and whole grains each taking up a quarter and very little fat. For moderate days, the portions of whole grains and fats should get a little larger, while fruit and vegetable servings shrink slightly and protein stays at a quarter. Finally, whole grains or starchy vegetables should take up about half of athletes’ plates on hard training days, since this is when they burn the most carbohydrates. Lean proteins and fruits and other vegetables should both make up a quarter, and fat intake can be higher.

Part of working with triathletes is being realistic, however. I know they are occasionally going to eat out, especially my college clients. To keep them on a healthy path, we look at online menus for their favorite restaurants and identify healthy options. Knowing exactly how to order can make a huge difference, as well. For example, I tell many triathletes to order double meat burrito bowls at Chipotle. That way, they can eat half for one meal and save the rest for another time.


Race day hydration and fueling build off the foundation I establish with triathlete clients in my initial assessment. Yet, the nature of the sport often requires us to make some adjustments to our established plan.

To start, despite my emphasis on proper fluid intake, triathletes don’t always start the race well hydrated. This can happen for a variety of reasons. Maybe they did not keep up with hydration during their travels the day before, or perhaps they are nervous after check-in and don’t feel like drinking before the race starts. Then, because they are unable to drink during the swim, they start the bike leg significantly dehydrated and must catch up for the run.

I also run into issues balancing how much triathletes should be drinking during a race with what is realistic. For example, say “Joe’s” bike sweat rate is 36 ounces per hour. He anticipates the bike leg of a particular race will take him one hour and 30 minutes to complete, so he needs to bring 54 ounces (36 x 1.5) of liquid on his bike. Most sports drink bottles are 20 to 24 ounces, so even if Joe drinks two on the bike, he’ll still be six to 14 ounces short. To remedy this, I might suggest that he station a small water bottle at his bike-to-run transition or attach a third bottle cage to his bike.

Joe might face a similar challenge on the run. He anticipates a time of 58 to 60 minutes, and he has a run sweat rate of 40 ounces per hour. There is an aid station every mile of the run, for a total of six hydration opportunities. Joe’s sweat rate divided across six aid stations indicates he should drink six to seven ounces per mile. Yet that’s unrealistic, since most triathletes are unable to consume more than five or six ounces at a time without experiencing gastric distress.

One solution is to have Joe carry a personal hydrator that he can clip to his running shorts. When he hits an aid station, he can unclip the hydrator, open it, pour the sports drink or water in, and then close it back up. The hydrator acts like a very slim sippy cup, so instead of having to consume large amounts of liquid at once, Joe can sip from it as needed. By drinking smaller amounts more often, he will still be able to reach his hydration goal for the run.

A third common challenge to race day hydration is the weather. This is why having extensive knowledge of sweat rates in different conditions comes in handy. I recommend athletes use a smartphone app that can give them hour-by-hour forecasts including temperature, humidity, wind, etc. Once they know what the weather will be, they can consult their SRTs and adjust their hydration plan accordingly.

For race day fueling, I tell triathlete clients to start preparing two to three days prior by upping their carbohydrate intake. Their largest meal the day before a race should be lunch, with a lighter meal in the evening (no big pasta parties!) and a small, carb-rich snack before bed. Triathletes also should not hesitate to salt their foods the night before a race, since the additional sodium will help them retain fluids the next day.

On the morning of the race, triathletes should focus on eating several small, carb-rich meals and sipping on a sports drink. A bagel with peanut butter and jelly is a classic choice, but some athletes enjoy toasted waffles or cold pasta-it really depends on what works for the individual. When a race doesn’t start until mid to late morning, I advise athletes to bring portable snacks they can tolerate even with a “nervous stomach.” Popular options include fig bars, pretzels, and jelly or honey sandwiches.

During a race, triathletes must take in enough carbohydrates to give them energy to cross the finish line. Inadequate carbohydrate intake can lead to low blood sugar, which brings symptoms like feeling faint, weakness, hunger, headaches, pounding heart, racing pulse, mouth numbness, and anxiety.

Generally speaking, a triathlete’s carbohydrate needs during a race vary depending on the course and intensity. A good rule of thumb for female triathletes is to consume at least 40 to 50 grams of carbohydrate per hour, with males needing a minimum of 60 grams per hour. However, finding the optimal dose for each athlete takes time and experimentation.

Because solid foods can cause gastrointestinal distress and are impractical to carry on the course, triathletes usually turn to gels and sports drinks for carbohydrate fuel during races. Sports drinks are well tolerated and provide the fluid, carbohydrates, and sodium necessary for athletic performance. They are my go-to recommendation for in-race fueling because they are widely available on most racecourses.

Many triathletes prefer to use gels during races, though, the majority of which are made up of a highly concentrated form of glucose called maltodextrin. Some athletes can be sensitive to large amounts of maltodextrin and experience belly bloating and other gastric distress when they consume it. To avoid this, I advise clients to pick gels that don’t include maltodextrin or select a chew or blok, which typically don’t contain maltodextrin. Athletes should always dilute the gels, chews, or bloks by consuming them with at least six ounces of water.

Whether they choose sports drinks or gels, I always tell triathletes to pack an additional carb source during a race “just in case.” It only takes a bottle of sports drink being launched off their bike for them to understand how important it is. By always having an extra bottle or pack of gels, they will always have an energy source available.

Although the race ends at the finish line, fueling does not. Recovery nutrition is incredibly important after the race. Most events offer a selection of carb- and protein-rich snacks at the finish line, such as chocolate milk, bagels, and bananas, but some athletes keep a cooler in their car with recovery foods they enjoy. Within a couple of hours after the race, triathletes should aim to eat a balanced meal.

Regardless of whether they are training or competing, the most important nutrition-related task for triathletes is knowing what their body needs and responding properly. When triathletes learn to master this skill, they will see the results on the course.


Triathlon became an NCAA Emerging Sport for Women in 2014 and has a strong club presence at the collegiate level. If at least 40 schools add varsity triathlon programs over the next 10 years, it will become a fully sanctioned NCAA championship sport. As the Team Dietitian for Northwestern University’s triathlon club team for the past five years, I’ve learned that nutrition for collegiate triathletes has its own unique challenges.

For instance, some athletes depend on the school’s food service facilities for their meals, while others live off campus and have to rely on their own skills to plan and prepare food. As Team Dietitian, I try to appeal to both groups by presenting sports nutrition clinics several times a year, providing individual consultations, and helping athletes prepare nutrition plans for competitions. When I’m not with the team, I know I can rely on one or two athletes I have trained to provide basic sports nutrition advice, like reminding everyone to fuel and hydrate during long bike workouts. Our team also collaborates with a chef for classes on how to prepare pre-exercise and recovery snacks, as well as batch cooking techniques.

One of the biggest challenges when working with collegiate triathletes is making sure they take in enough calories and protein as their training increases. Healthy snacking becomes very important, and to help with this, the team coordinates large orders of Clif and fig bars.

Planning for adequate recovery meals after late-night workouts is difficult, too. These are very hard workouts, and even after their typical recovery snack, some athletes wake up starving in the middle of the night. Our solution is to come up with snacks that provide adequate calories and protein to allow for a restful night’s sleep.

Linda Samuels, MS, RD, CSSD, LDN, is the owner of Training Table Sports Nutrition, LLC, a private nutrition consulting practice in Chicago that specializes in working with endurance athletes, particularly triathletes. She also is the Team Dietitian for the Northwestern University triathlon club team and works with professional boxers. Samuels can be reached at: [email protected].

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