Ultra Cycling Nutrition – How to Fuel for an Endurance Race

Proper fueling during a long-duration event/race (200 miles to 500+ miles) is something that can’t be taken lightly… the quality of the fuel you put in your body—as well as the quantity of that fuel—needs to be seriously considered if you hope to enjoy a successful event.  Hopefully, you’ve been testing your fueling plan for several weeks and under various conditions.  Doing so will give you a good “game plan” coming into your event/race.

Here are a couple of suggestions that I believe you should employ prior to and during the event:

In The Few Days Leading Up To The Event/Race:

Avoid the temptation to train too much and/or too close to event/race day! – You will not be able to positively influence your fitness level in the days leading up to your event/race; however, you can negatively impact your performance by training during that time (training meaning anything of significant duration or intensity).  As well-known coach Jeff Cuddeback states, “The week prior to any event of a long duration should be all about resting up and topping off your energy stores. Training is done to keep the engine lubed and tuned up, nothing more. If you think you’re going to further your fitness through training the week of your key event/race, you’re sadly mistaken.  If you are the type to train right up to the event, you will almost certainly under perform.”

Best performances in long-duration events are achieved by getting to the starting line well rested rather than razor sharp.  In doing so, you may find yourself not hitting on all cylinders during those first few minutes.  In fact, you might even struggle a bit at the beginning of the event/race.  However, your body will not forget all the training you’ve done and it will absolutely reward you for giving it the time it needed to “soak up” all of that training.

Don’t let your diet deviate too much from what got you there in the first place!


Don’t drink excess amounts of water in the hopes of getting a head start on your fluid requirements for the event/race.   Consumption of roughly 0.5 to 0.6 of your body weight is a good gauge in regards to how much water you should be consuming daily (example: 180 lb/approx 82kg athletes should drink approximately 90-108 ounces/approx 2.7-3.2 litersof water daily). However, if you’ve not been following this recommendation consistently, don’t start now, as this will overwhelm your body with too much fluid too soon, which may increase the potential for hyponatremia.


Don’t stuff yourself with extra food in the hopes that you’re “carbo loading.”  The time period for carbohydrate loading (i.e., maximizing muscle glycogen storage capabilities) has, for all intents and purposes, passed.  In essence, “carbo loading” is what you did in the 0-60 minutes after all your workouts leading up to the race.  That’s when the glycogen synthase enzyme—which controls glycogen storage—is most active, and that’s how you topped off your glycogen stores.  Any excess food you eat in the days leading up to the race is either going to be passed through the bowels or stored in adipose cells… neither of those things will benefit you.


Don’t consume extra sodium (salt) in the hopes that you’ll be “topping off your body stores” prior to the event/race. Since the average American already consumes approximately 6000 to 8000 mg per day (if not more), an amount well above the upper end recommended dose of 2300-2400 mg/day, there is absolutely no need to increase that amount in the days prior to the race.  (Hint: Adopting a low-sodium diet will do wonders for both your health and athletic performance).  High sodium intake, especially in the days leading up to the event/race, is a recipe for disaster because it will greatly increase the potential for disruption of the hormonal mechanisms that control sodium regulation, re-circulation, and conservation.  In the days leading up the event/race, be especially cognizant of the salt content in your foods, especially if you go out to eat. Restaurant food is oftentimes loaded with sodium, so dining out can dramatically increase your already high salt intake.

The Night Before Your Event/Race:

Eat clean, eat until you’re satisfied, then call it a night

You can’t positively affect muscle glycogen storage capabilities the night before an event/race, a time when the glycogen synthase enzyme—which again, is the enzyme that controls glycogen storage—is inactive (hint: that’s why post-workout refueling is so important).  Consume complex carbohydrates, some high-quality protein, and low-to-no saturated fat, make sure your meal is low in sodium, and be sure to drink sufficient amounts (but not too much) of water.  Skip the alcohol, fatty foods, and dessert… save those “rewards” for after the event/race.

The Morning Of The Event/Race:

No calories three hours prior to the race.

The first fuel your body will use when the race begins is muscle glycogen (again, this is why post-workout refueling is so vital).  Eating a pre-race meal at the wrong time will negatively affect how your body utilizes its finite stores of glycogen, which will negatively impact your performance.  If you have a comfortable 3-hour window in which to complete a small (200-500 calorie) meal, go for it.  Otherwise, simply start the event/race on an empty stomach (trust me, you’ll be fine) and begin refueling shortly after you begin, approximately 20-30 minutes after the start.

Once The Event Begins

The human body has so many survival safeguards by which it regulates living one more minute, that when we try too hard to fulfill all its needs we interfere, doing more harm than good.  If I replace all the fuels I lose at the rate of 700–900 calories per hour, I bloat, vomit, present diarrhea, and finish the event walking or at an aid station.  If I replace all the fluids lost all at once, I end up in the emergency tent with an IV for dilutional hyponatremia.  If I replace all the sodium my body loses at the rate of 2 g/hour, I end up with swollen hands, eyes, ankles, feet, and noticeably labored exercise, or hypernatremia–induced bonking.

At an easy aerobic pace, the rate of metabolism increases from a sedentary state to a range of 1200–2000%.  As a result, the body goes into “survival mode” where blood volume is routed to working muscles, fluids are used for evaporative cooling mechanisms, and oxygen is routed to the brain, heart, and other internal organs.

Interestingly, it is NOT focused on calorie, fluid, and electrolyte replacement, as some of the “experts” advise.

The goal in fueling is to postpone fatigue for as long as possible.  The human body is simply not equipped to replace “X” out with “X” or “near-X” when it comes to calories, fluids, and electrolytes.  Fortunately, the body has many built-in mechanisms that effectively bridge the gap between what it’s losing and what it can comfortably accept in return from your fuel donation.  For example, the body has as nearly limitless supply of calories available from body fat stores.  These calories become the body’s “fuel of choice” during prolonged exercise, and effectively bridge the gap between what it’s losing and what it can comfortably accept in return from your fuel donation.  That’s why your focus should NOT be “How many calories can I consume before I get sick?”  but rather, “What is the least number of calories I need to consume to keep my body doing what I want it to do hour after hour?”

Additionally, though many a so-called “experts” might suggest otherwise, the body cannot “learn” how to accept and utilize more calories and fluids as you become fitter… this is simply not true.  What is true is that the body, as part of its adaptation to your training (as you become fitter), will become more efficient in its use of fluids, as well as its “fats for fuel” capabilities.  It will also become more adept at utilizing, recirculating, and thus conserving its stores of sodium.

Fueling this way—the “less is best” approach—makes much more sense, if only because a “not enough calories” problem is significantly easier to fix an “uh oh, I overdid it” problem.

How Much Fluids, Calories, And Electrolytes Do I Need?


Optimum nutritional support for endurance athletics means consuming the right amount of the right nutrients at the right time.  You can neither overload nor undersupply your body without compromising athletic performance and incurring detrimental results.  The principle of avoiding both too much and too little especially applies to hydration, where serious consequences occur from either mistake.  If you don’t drink enough, you’ll suffer from unpleasant and performance-ruining dehydration.  Drink too much, however, and you’ll not only end up with impaired athletic performance, you may even be flirting with potentially life-threatening water intoxication.

One of the most respected researchers on hydration, Dr. Tim Noakes, studied the effects of thousands of endurance athletes and noted that the front-runners typically tend to dehydrate, while over-hydration occurs most often among middle to back-of-the-pack athletes.  Both conditions lead to hyponatremia (low blood sodium), but through different processes.  Excess water consumption causes what is known as “dilutional hyponatremia,” or an overly diluted level of sodium and electrolytes in the blood.  This is as bad as under-hydrating in regards to increased potential for muscular cramping, but has the added disadvantages of stomach discomfort, bloating, and extra urine output.  And, as mentioned earlier, in some unfortunate circumstances, excess hydration can lead to severe physiological circumstances, including death.

Unfortunately, endurance athletes too often adopt the “if a little is good, a lot is better” approach.  This can lead to significant problems when you’re trying to meet your hydration requirements.  All it takes is one poor performance or DNF due to cramping and you start thinking, “Hmm, maybe I didn’t drink enough.”   Next thing you know, you’re drinking so much water and fluids that your thirst is quenched but your belly is sloshing and you’re still cramping.  Remember, both undersupply and oversupply of fluid will get you in trouble.

How much should one drink?  One expert, Dr. Ian Rogers, suggests that between 500-750 milliliters/ hr (about 17-25 fluid ounces/ hr) will fulfill most athletes’ hydration requirements under most conditions.  All athletes would benefit from what Dr. Rogers says: “Like most things in life, balance is the key and the balance is likely to be at a fluid intake not much above 500 milliliters (about17 ounces) per hour in most situations, unless predicted losses are very substantial.”


Too many endurance athletes fuel their bodies under the premise, “If I burn 500- 800 calories an hour, I must consume that much or I’ll bonk.”  This is an undeniable mistake, as Dr. Bill Misner explains: “To suggest that fluids, sodium, and fuels-induced glycogen replenishment can happen at the same rate as it is spent during exercise is simply not true.  Endurance exercise beyond 1-2 hours is a deficit-spending entity, with proportionate return or replenishment always in arrears.  The endurance exercise outcome is to postpone fatigue, not to replace all the fuel, fluids, and electrolytes lost during the event. It can’t be done, though many of us have tried.”

Simply put, your body can’t replenish calories as fast as it expands them (ditto for fluids and electrolytes).  Athletes who try to replace “calories out” with an equal or near equal amount of “calories in” usually suffer digestive maladies, with the inevitable poorer-than-expected outcome, and possibly the dreaded DNF.  Body fat and glycogen stores easily fill the gap between energy output and fuel intake, so it’s detrimental overkill to attempt calorie-for-calorie replacement.

Keep this in mind if you’re doing ultra-endurance events, especially if you’ve had to “alter the game plan” and are unable to stick to your planned hourly caloric intake.  For example, let’s say you’ve been consuming an average of 250 calories an hour, but the heat or other circumstances (such as climbing a very long hill) prevent you from maintaining that desired hourly average.  DO NOT try to “make up lost ground” by consuming additional calories; it’s not only unnecessary, it may very well cause a lot of stomach distress, which will hurt your performance.  Remember, during periods where fuel consumption may be less than your original hourly plan, body fat stores will effectively fill in the gap, thus eliminating the need to overcompensate with calories.

During exercise, the average-size athlete’s liver can effectively return 4.0 to slightly over 4.6 calories per minute back to the energy cycle.  That’s 240-280 calories per hour MAXIMUM for the average-size athlete under normal conditions.  However, we have consistently noted that most athletes do well on even fewer calories, so “average size” athletes (approximately 160-165 lbs/approx 72.5-75 kg) should look at that 240-280 gauge only as a reference point.  Lighter weight athletes (<120-125 lbs/ approx 54.5-57 kg) will most certainly need less, while heavier athletes (>190 lbs/approx 86 kg) may need slightly more on occasion, the key word being “may.”  Remember, the thousands and thousands of calories from body fat stores will very easily bridge the gap between what you’re burning and what your body can comfortably accept from your fuel donation.

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Consuming sufficient amounts of calories and fluids during workouts and races is an obvious necessity. Consistent electrolyte supplementation is equally important.  Just as your car’s engine requires sufficient oil to keep its many parts running smoothly, your body requires electrolytic minerals to maintain smooth performance of vital functions such as muscle contraction.  Athletes who neglect this important component of fueling will impair their performance, and may incur painful and debilitating cramping and spasms, a sure way to ruin a workout or race.

However, this doesn’t mean that athletes should indiscriminately ingest copious amounts of one or more electrolytes; salt (sodium chloride) is usually the most misused.  Supplementing with only one electrolyte or consuming too much of one or more electrolytic minerals overrides the complex and precise mechanisms that regulate proper electrolyte balance.  The average athlete stores at least 8,000 mg of dietary sodium in tissues and has these stores available during exercise.  In other words, you already have a vast reservoir of sodium available in your body from your diet, ready to serve you during exercise.  In addition, your body has a highly complex and efficient way of monitoring and recirculating sodium back into the blood, which it does to maintain homeostasis.  You do need to replenish sodium during exercise, but you must do so with amounts that cooperate with, and do not override, these complex body mechanisms.

The solution is to provide the body with a balanced blend of these important minerals in a dose that cooperates with and enhances body mechanisms.  Salt tablets alone cannot sufficiently satisfy electrolyte requirements, and excess salt consumption will cause more problems than it resolves.  Dr. Misner explains: “When a balance of cations (positively charged ions) to anions (negatively charged ions) are managed in the energy-producing cell—assuming the cell has adequate fuel and fluid—such a cell will produce energy at a higher rate than one overdosed by a single cation mixed with an irrational list of anions.”  Simply put, your body will perform better with a balanced supply of electrolytes than with just a dose (especially a large one) of sodium or any other single mineral.

Additionally, remember that electrolyte replenishment is important even when it’s, not hot outside.  Sure, you may not need as much as you would in hotter weather, but your body still requires consistent replenishment of these minerals to maintain the optimal performance of many important bodily functions.  You don’t wait until you dehydrate before you drink fluids, or until you bonk before you put some calories back in your body, do you?  Of course not.  You fulfill your fueling requirements before the consequences of inadequate replenishment strike.  The same principle applies to electrolyte replenishment.  Going back to the engine/oil analogy, you don’t wait until the engine seizes before refilling the oil reservoir.  The same is true for electrolytes, the body’s “motor oil,” in that you don’t want to wait until you start cramping before you replenish these important minerals.

Consistent replenishment of fluids and calories is essential to maintain energy levels during workouts and races.  Providing consistent replenishment of electrolytes is an equally important component of proper fueling.  Getting fluid and caloric needs dialed in is fairly easy to accomplish, but fulfilling electrolyte needs requires more attention and fine tuning because many more variables need to be accounted for:

  • Unique biological predisposition in terms of minerals lost via perspiration
  • Differences in an athlete’s size and fitness
  • The pace of exercise
  • The humidity and heat, and how well or poorly the athlete is acclimated to it

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