Nutrition During Intense Training

Maintaining proper nutrition intake during heavy blocks of training with multiple sessions per day or during multi-day races can be quite a challenge for most athletes.  There are several areas of concern that need to be addressed to ensure that adequate energy stores are available for high output racing or training, as well as for recovering from those sessions to be prepared for the next day’s training session or race.  Critical factors to consider include: total energy intake and macronutrient balance, hydration maintenance, and optimizing the timing of pre and post session nutrition needs.  The following article will review some of these concerns so a proper diet can be established.  For your benefit we also include a three day diet recall from 2012 Triathlete of the Year, Cameron Dye and Olympian and National Champion cyclist Evelyn Stevens.

Cameron Dye-three day food consumption

Evelyn Stevens-three day food consumption


Energy Balance

            The amount of energy that is expended during heavy training and racing can be extremely high, and failing to keep a close balance between energy expenditure and energy intake can lead to poor performance and even signs and symptoms of overtraining.  For cyclists who use a power meter, it is fairly easy to get a handle on the total amount of energy expended during training or racing on the bike by looking at the kilojoules (Kj) that are expended in each training session or race.  Even though in actual conversion there are 4.18 Kj per Calorie, the human body is only 20-25% efficient in terms of converting the chemical/food energy into actual power output at the pedal.  Therefore, if your power meter says that you burned 1800Kj of energy during a training session or race, you would have burned about 1800 Calories of food energy.  There is a relationship between the intensity of effort and the ratio of carbohydrate and fat that is burned that can be measured in a well equipped exercise physiology lab by a process known as indirect calorimetry.  In the absence of that kind of equipment and testing, it is reasonably accurate to consider that most well-trained athletes will burn about a 50/50% mix of carbohydrate and fat at low to moderate intensity training (aerobic endurance training).  As you work harder, the percentage of carbohydrate that is utilized will increase to nearly 80% or higher as you approach your lactate threshold (pace/power/speed that can be maintained for 1 hour, going all out).    The graph below shows the progression of heart rate, blood lactate, and then carbohydrate and fat use (displayed as calories per hour) for a well-trained runner during a progressive exercise test known as the FUEL test conducted at Boulder Center for Sports Medicine.  You can see that at low intensities, that this athlete actually utilizes even more fat than carbohydrate, but that as he reaches his threshold that the carbohydrate use skyrockets and fat use plummets.  Knowing this information can be very helpful when preparing for ultra-distance competitions where energy balance becomes a critical factor for success.

Fuel Chart2



Keep in mind that once you have determined your exercise-related energy needs, you also need to consider your resting metabolic rate, which is typically about 10 X your body weight in pounds as a number of Calories per day.  For multisport athletes and non-cyclists, calculating actual energy use during exercise is more difficult since true power meters do not exist for most other activities than cycling, but it can be estimated using a resource like:  In addition, about 10% of all the energy that you eat is burned in converting it into usable energy – which is known as the Thermic Effect of Food (TEF).  There is also a good calculator available here  that will allow you to estimate total daily energy needs.  A 165 lb man riding 2 hours at fairly high intensity could require about 3500 Calories for the entire day.  This energy need is significant, but manageable with a relatively normal diet.


Once you consider more extreme training & racing, where daily energy needs can exceed 5,000 Calories a day then things get interesting.  Trying to eat a balanced athletic diet with a macronutrient breakdown of 40-50% carbohydrate, and between 20-30% each of fat and protein might not be realistic.  Knowing that the upper limit needs for protein are at approximately 1 gram per pound of body weight, for our 165-lb man we would have about 660 Calories coming from protein to meet protein needs…which would be only about 13% of a 5,000 Calorie daily intake.  You can read more about protein here: On these high energy intake days, we often see a shift to a higher percentage of fat intake, ideally with the healthier unsaturated fats like those found in nuts and nut butters, avocadoes, olive oil, etc.  Carbohydrate needs are significant and can’t be overlooked, but during these intense training and racing days the amount of carbohydrate taken in during exercise can be significant.  It would be fairly normal for an athlete to use an entire flask of EFS gel (100 grams carbohydrate) as well as a 20-ounce bottle of EFS drink mix (1 & 2/3 scoops, approx. 40 grams carbohydrate) during an intense 2 hour bike race.  The total carbohydrates from just those two fuel sources contains 140 grams, or 560 calories worth of carbohydrates.  There is a great article on fueling during exercise here: The pre-event/training session meal eaten 2-3 hours prior to the workout or race should also be predominantly carbohydrate based and might often contain another 600-800 calories of carbohydrate.  This meal should contain relatively low amounts of fats and protein, as digesting those both takes significantly longer than carbohydrates.  A post session or race recovery drink is also a very good idea to help replete glycogen stores rapidly, and should be consumed within 30-minutes of the end of exercise.  A serving of Ultragen contains an ideal balance of 60 grams (240 Calories) of carbohydrate and 20 grams (80 Calories) of protein.

Adding the pre-event meal, carbohydrate intake during the 2-hour race, and a serving of Ultragen for recovery, our 165-lb man would have taken in approximately 1400-1600 calories of carbohydrate, which does not include any additional snacks or meals beyond the pre-event meal.  For this example, eating a balanced dinner as well as possibly a snack or two will easily get him to his goal intake of 3,500 Calories for the day.  If this athlete was instead needing more than 5,000 Calories then looking for some extra high nutrient dense foods is going to be likely.  I have watched professional cyclists during a Grand Tour go to the food buffet and eat 3 full plates of food that would be considered a normal 800 calorie meal in each trip.  Eating 2400 Calories all at once in most settings might not be advisable, but during a major race you sometimes just need to eat when you can.  Eating a small snack just before bed, and also keeping a small snack right next to your bed can help keep you from waking up with extreme hunger during heavy phases of training or racing.


            Fluid and electrolyte needs during intense training and racing are quite variable from person to person, and will also be high variable based on the environmental conditions, as well as your conditioning relative to the environment.  Figuring out your fluid needs during exercise can be done relatively easily using pre/post body weight measurement.  For more specific information on fluid and electrolyte needs during exercise please see:  As a simple rule, drinking 1 liter of water per day in addition to your exercise fluid losses should help you maintain proper hydration.  Weighing yourself at the start of end of each training session as well as in the morning and at night can also give you some idea regarding your fluid balance.  Some ProTour cycling teams weigh their riders before and after each stage to determine the riders’ fluid needs to regain hydration balance.  As a rule of thumb in normal conditions, most athletes will need between 1 and 2 bottles of fluid per hour of moderate exercise.  Extreme conditions and individual variations can lead to these fluid needs doubling, though.  On the flip-side, there are also athletes with incredibly low sweat rates whose fluid intake needs are far below average.  Tracking your weight, urine frequency and even color (keeping in mind that many vitamins can cause changes in urine color irrespective of fluid balance) can be helpful tools for monitoring your hydration level.  Resting heart rate and exercise heart rate for a given power/pace might also give you an idea of your hydration level, as with dehydration the blood viscosity is increased and heart rate will be elevated.

Meal Timing

            The typical time for many athletes who compete is for a morning start, but there are many other times where training and even racing is done throughout the day.  In most cases, a pre-event meal should be consumed between 2-3 hours prior to the event.  As mentioned above, this meal should be primarily carbohydrate based with minimal protein and especially minimal fat content.  It is important to have some sort of food routine, especially for competition so that you know your stomach will react similarly each time you race.  Even though it is incredibly common in Asia, I have many people look at me funny when I eat rice for breakfast as my pre-event meal.  I typically also have a scrambled egg and a little bit of ham, olive oil, and a dash of Parmesan cheese added to my breakfast rice.  The other pre-event staple meal for me is steel cut oats with honey, almond butter, and rice milk.   Completing the pre-event meal in the 2-3 hour window before a competition is sometimes a challenge, especially for early-start events like Ironman, but it is still important.  Organization and preparing the meal before going to bed often makes for an easier and smoother morning routine.

Post-training and post-race meals should ideally be consumed within an hour of completing exercise.  Even if you are going to have a post-race meal within 1 hour of finishing a race or training session, I still encourage athletes to consume a recovery drink as soon as possible after the finish to take advantage of the window to get glucose back into the muscles as soon as possible.  For the post-event meal, I like to focus on quality carbohydrate sources like potatoes or rice, as well as quality protein and healthy anti-inflammatory foods with high micronutrient content like kale, blueberries, and beets.



4 replies
  1. Bizitrac
    Bizitrac says:

    Absolutely awesome information. I have my first 100k coming up in 9 days here in Australia and have been procrastinating over nutrition and hydration during each stage for a few days now. Of course I’ll be using my flasks of EFS but have been concerned about other aspects. Very timely advice indeed so thanks heaps. 

  2. MichaelFerree
    MichaelFerree says:

    This is great info! 
    Side note: you guys need to add a social bookmarking plugin so we can quickly and easily share it to twitter and facebook. Since you are using wordpress, it should be really easy to implement.


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