The Truth Behind Carb Loading

How will this popular nutrition practice impact ultimate players' athletic performance?

pasta

For many ultimate teams, the night before a tournament weekend is a time to settle in to where you’re staying, relax with teammates, and grab a meal together. Often this will include a pasta dinner since it’s cheap, quick and easy to make for a large group, and falls into the appealing category of “carb loading,” which many athletes learned long ago to swear by as a means to fuel your body for a weekend of exertion.

But is carb loading actually a boon for your body?

The History Behind Carb Loading

In the 1960s, a Swedish physiologist, Gunvar Ahlborg, discovered that carbohydrates are stored in the muscles and liver as glycogen. This glycogen is stored fuel, and — although it depends on our exercise intensity and our training — once it runs out, we reach fatigue: we hit that wall where exercising more seems impossible. Ahlborg confirmed that there was a positive correlation between the amount of glycogen stored in our muscles and endurance performance: the more glycogen (i.e. fuel in the tank), the longer an athlete could run.

Ahlborg also found that intentionally depleting glycogen stores by drastically limiting carbohydrate intake and then performing exhaustive exercise made it possible to store “extra” glycogen when large amounts of carbohydrates were added back into the diet. Originally referred to as glycogen supercompensation, “carbohydrate loading” was coined as a strategy to maximize the amount of glycogen a body could store in order to delay fatigue and promote endurance among athletes.

Armed with this seemingly powerful new athletic strategy, Ahlborg subsequently developed the first protocol for carbohydrate loading: a seven-day plan starting with one day of exhaustive exercise followed by three days of light training with very low-carb intake (about 10% of daily caloric needs) and then three more days of light training with very high-carb intake (about 90% of daily caloric needs). Participants not only increased glycogen storage capacity, but also showed increases in endurance.1

Carb loading clearly worked. Pasta producers everywhere rejoiced.

However, many athletes had trouble following Ahlborg’s protocol; they — unsurprisingly — found it exhausting and too stressful to follow before an important event. Some even experienced gastrointestinal distress.

And so, modified versions of the carbohydrate loading strategy were developed, taking into account new research. Most notably, the exhaustive exercise portion and depletion phase were removed from most protocols due to their unmanageability. Research from the 1990s found that similar levels of glycogen supercompensation could be achieved among well-trained athletes in just two or three days without any of the negative side effects. The newest protocol, known as the Western Australian Method, condenses high-intensity exercise and carbohydrate loading into just a single day.2

Carb Loading Protocols

 Day 1Day 2Day 3Day 4Day 5Day 6
Classic 6-day method20% CHO
Exhaustive exercise
20% CHO
Light activity
20% CHO
Light activity
90% CHO
Exhaustive exercise
90% CHO
Light activity
90% CHO
Rest
Modified 6-day method50% CHO
Taper exercise
50% CHO
Taper exercise
50% CHO
Taper exercise
70% CHO
Taper exercise
70% CHO
Taper exercise
70% CHO
Rest
3-day method---75% CHO
Normal training
75% CHO
Normal training
75% CHO
Rest
Western Australian 1-day method----Normal diet
Exhaustive exercise
10-12 g/kg body weight
Rest

((CHO = % of daily caloric intake that should be carbohydrates))

Do You Need To Carb Load?

Sorry to everyone who uses a tournament, or even practice, as an excuse to indulge in multiple bowls of pasta on a Friday night: for an ultimate player, carb loading is probably unnecessary.

Yes, research has shown that when athletes run out of glycogen, they fatigue quickly; and yes, research has also shown that carb loading effectively increases glycogen stores. But, ultimate players — unlike marathon runners, triathletes, long-distance swimmers, or cyclists — do not continuously exercise for 90 minutes or longer without access to food. Those are the parameters under which carbohydrate loading has been shown to be effective. Elite ultimate players probably have access to a variety of fuel sources basically every five minutes;3 regardless, they are able to constantly add immediate fuel to the tank.

Given that, carbohydrate loading may even slow you down. For individuals who aren’t used to eating large amounts of carbohydrates, it can cause bloating and other gastrointestinal problems.

It also adds non-functional weight: each gram of glycogen stored in your body is bound to 3-4 grams of water, which means that you can easily gain more than a few pounds after a night of carb loading. Those extra pounds, which are mostly water, might even negate the benefits of carb loading in the first place.

Takeaway

As with everything nutrition-related, it’s important to figure out what works for you. Carbohydrate requirements differ based on a number of factors including weight, exercise intensity and duration, what an athlete normally eats (lower or higher carb diet?), and when an athlete last ate.

If you usually feel like you hit a wall during a tournament, it might be time to play around with what you’re eating the night and morning before a tournament — as well as how you’re fueling during and between games.4

For most ultimate players, sufficient glycogen stores — not extremely high stores, which would result from carb loading — should be more than enough to promote optimal performance, especially given our ability to refuel during and between games. General sports nutrition recommendations currently suggest 5-8 grams of carbohydrates per kilogram of body weight per day — that’s 320-520 grams of carbs for a 140-lb person — although athletes training at extremely high volumes may benefit from slightly higher amounts (8-10 g/kg body weight).

It’s also important to note that, as with most nutrition literature, these studies were performed in a lab with a small number of (usually male) cyclists. Those settings aren’t anywhere close to what the majority of ultimate players live in: we have jobs and families and social events that would make adhering to a carb loading regimen, or at least the depletion phases, very difficult.

The application of carb loading to real world athletes is even more dubious for women. Few studies have investigated the effects of carb loading in women, but of those that have, the majority found that carb loading enough to improve performance may not be feasible in women. Women have lower energy needs than men, but still need similar grams of carbohydrate per kilogram of body weight to reach glycogen supercompensation. As a result, they would need to exceed their daily energy needs or forgo protein and fat entirely to eat enough carbohydrates — neither of these alternatives would be worth the extra glycogen boost.56

So next time a teammate offers to host a pre-tournament dinner, maybe pass on the second helping of pasta. As always, just eat more vegetables instead.


  1. Ahlborg B, Bergström J, Ekelund LG, Hultman E. Muscle glycogen and muscle electrolytes during prolonged physical exercise. Acta Physiol Scand. 1967;70:129–142 

  2. Fairchild TJ, Fletcher S, Steele P, Goodman C, Dawson B, Fournier PA. Rapid carbohydrate loading after a short bout of near maximal-intensity exercise. Med Sci Sports Exerc. 2002; 34(6):980-6. 

  3. Perhaps a little longer if it’s windy or a just plain sloppy game 

  4. Pro tip: figure this out at practice, not before an important tournament! 

  5. James AP, Lorraine M, Cullen D, Goodman C, Dawson B, Palmer TN et al. Muscle glycogen supercompensation: absence of a gender-related difference. J Appl Physiol. 2001; 85(6):533-8. 

  6. Tarnopolsky MA, Zawada C, Richmond LB, Carter S, Shearer J, Graham T, Phillips SM. Gender differences in carbohydrate loading are related to energy intake. J Appl Physiol. 2001;91(1):225-30. 

  1. Kate Schlag

    Kate is a Registered Dietitian and holds a Masters in Public Health with a concentration in nutrition from the University of California, Berkeley. As an RD, she is looking forward to a career in sports nutrition and nutrition communications. She started playing ultimate with USC’s Hellions of Troy and now plays for San Francisco Polar Bears.

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