Joshua Gordon, PhD

 

In this blog, I want to discuss carbohydrate intake prior to ultra endurance events like Ironman triathlons. Carbohydrates are the primary fuel source used in triathlon, especially as the intensity and duration of activity increase. Carbohydrate loading, or carb loading, is often used to increase endurance performance. It works by increasing the amount of carbohydrate stored in muscles as glycogen and somewhat by increasing the amount of carbs stored in the liver. By increasing the amount of carbohydrates consumed prior to a long endurance event, you can go longer, harder, and potentially faster. Loading carbohydrates before an event is not a substitute for intra-event fueling but could give you a slight edge both in terms of performance and in terms of recovery.

 

My motivation for writing this blog is threefold. First, this is an extremely common question with tons of information out there. Some of that information is great, some of it, well, I do not agree with. I am not here to tell you what to do but to document what I do and it has worked well for me in 7 full-distance triathlons and countless 5+ hour endurance training days. Second, before an event, I often have doubts even though my approach is tried and true, and this blog will serve as a personal reference on the protocol to follow even if there are some doubts circulating through the pre-race mind. Lastly, by putting my opinion and approach out there, I hope to get feedback and hear from others on their approaches, for what has worked and what has not worked, so please feel free to comment below if you disagree with me.

 

Understanding Carbohydrate Loading

 

Carbohydrate loading, commonly referred to as carb loading, has its roots in the late 1960s. It was then discovered that combining exhaustive exercise with a subsequent high-carbohydrate diet led to a super compensation effect, significantly boosting glycogen storage in muscles. This approach evolved in the 1980s, when it was found that tapering exercise and increasing carbohydrate intake for several days also effectively increased glycogen storage. Today, it's a well-established fact that athletes can enhance glycogen storage in both type I and II muscle fibers by elevating their carbohydrate intake for 24–48 hours.

 

The science behind this involves a few key processes. During the high-carbohydrate phase, the body becomes more sensitive to insulin, which plays a crucial role in transporting glucose into muscles for storage as glycogen. Additionally, a high intake of carbohydrates prompts an increase in enzymes that facilitate glycogen synthesis, thereby expanding the muscles' capacity to store energy.

 

What carbohydrate loading essentially does is maximize the body’s energy storage capabilities. This additional glycogen reserve is vital during endurance events, helping delay the onset of fatigue and improving overall performance. Research indicates that carbohydrate loading can boost glycogen stores by as much as 50%. This range of 20-50% is widely cited in sports nutrition and exercise physiology.

 

A key study in the realm of glycogen metabolism during exercise is 'A study of glycogen metabolism during exercise in man' by Bergström and Hultman, published in 1967. This study has been fundamental in illustrating how carbohydrate loading can significantly increase glycogen levels. In well-trained and adequately nourished athletes, muscle glycogen concentration is typically around 150 mmol/kg wet weight after a rest period of at least 8–12 hours. However, this level can be substantially elevated in highly fit and rested athletes who follow a high-carbohydrate diet over several days. Through such a regimen, glycogen levels can reach super-compensated states, going as high as 200 mmol/kg wet weight.

 

Many studies have found that when you deplete your muscle glycogen through weight training and/or endurance exercise, your total muscle glycogen stores will increase above baseline. This effect is known as "glycogen super compensation." You might have experienced this phenomenon accidentally if you engage in some really hard training followed by 1-2 days of rest or easy activities. Your quads or glutes may feel bigger, or even your biceps or shoulders might fill out your shirt a bit more. (Hingst 2018)

 

For a primer on carbohydrate metabolism, I recommend reviewing "Fundamentals of Glycogen Metabolism for Coaches and Athletes" by Bob Murray and Christine Rosenbloom. This paper offers a comprehensive review of the subject, ideal for anyone looking to expand their knowledge in this area (Murray 2018) .

 

Glycogen storage in the human body is relatively limited compared to body fat. Carbohydrates are primarily stored as glycogen, mainly in the liver and muscles. Typically, the liver stores about 100 grams of glycogen, while muscles store approximately 400 grams. Additionally, around 5 grams of glucose circulate in the bloodstream. (Hearris 2018) Some studies have reported glycogen storage capacity up to 700 grams, which is largely dependent on muscle mass; larger athletes tend to have a higher glycogen storage capacity. As per Table 1 in "Fundamentals of Glycogen Metabolism for Coaches and Athletes," the normal range for muscle glycogen storage is between 300-700 grams, with the liver storing an additional 0-160 grams (Murray 2018) .

 

The mention of 0 grams in the liver might seem surprising. This could refer to extreme cases where liver glycogen is completely depleted, possibly due to prolonged, intense exercise or fasting. However, such situations are quite rare and typically not representative of normal conditions. Liver glycogen levels are usually maintained to support essential bodily functions, especially for regulating blood glucose levels.

 

A short note on salt loading and using caffeine to increase the rate of glycogen uptake. 

 

Sodium loading is a nutritional strategy often used by endurance athletes, particularly in events with high sweat rates and expected sodium losses, such as long-distance triathlons. I’ve found that sodium loading is more effective for a full Ironman than for a marathon because by the time you get to the weight-bearing movement of running, you will have shed many of the extra pounds resulting from increased fluid storage. For example, if my normal body weight is 72 kg, I may start a full Ironman at 76 kg but be down to 71 kg by the time I get to the run (of course, this is impossible to know in most circumstances, but it's just a guess). Actually, back in the day, they used to weigh athletes during the race itself in Kona. As mentioned in a Slowtwitch article (Empfield 2022):

 

Suffice it to say, it made sense to load up on carbs and sodium to keep your hydration levels up. 

 

I do not think it’s as good for a marathon for a few reasons. First, marathons are much shorter, so even if you lose 1 kg of fluid mass per hour, you likely will not be nearly as close to being severely dehydrated as during a 10+ hour race. Second, running a marathon is weight-bearing from the first step, and being too heavy can slow you down, so there is less advantage to be gained by coming in heavy and loaded up.

 

Salt loading is a strategy of gradually increasing sodium intake in the days leading up to an event. Athletes do this by integrating saltier foods and sports drinks into their diets. This practice can help prevent hyponatremia, a potentially deadly condition marked by low blood sodium levels that can impair performance. By carefully managing sodium intake, athletes seek to improve their body's ability to maintain fluid balance and optimal hydration during races. A study called "Sodium loading aids fluid balance and reduces physiological strain of trained men exercising in the heat" demonstrated that consuming high-sodium beverages before exercise can expand plasma volume, alleviate thermoregulatory and perceived strain during exercise, and boost exercise capacity in warm conditions (Sims 2007).

 

Additionally, caffeine has been shown to enhance the body's ability to store carbohydrates as glycogen in muscles. A double-blind, crossover, randomized clinical trial involving endurance-trained men revealed that drinking a coffee beverage (coffee with milk) after exhaustive exercise resulted in significantly greater muscle glycogen recovery than a control beverage (milk alone), as reported in a 2021 study published in Nutrients (Loureiro 2021).

 

Regarding my personal approach, I typically do not taper my caffeine use prior to races. While some suggest tapering, I believe in maintaining homeostasis as much as possible. This means not making significant changes, even during the final taper week of race preparations. Keeping things consistent helps me stay balanced and prepared for the demands of the race.

 

Won’t I gain weight? 

 

Yes you will gain weight in the short term by following this protocol which is why I do not really recommend you weigh yourself.  The thing is, most of that weight is going to be water and carbohydrates stored as glycogen. With every gram of carbohydrate we store about 3-4g of water.  If you are normally storing 300g of glycogen and that increases to 700g due to carb loading, you can expect to gain 1.6kg of weight just from that.  Once you add in sodium loading and the foodmass associated with eating all of that food we are talking about a 2-4kg increase without batting an eye.  

 

The real question you may be asking is:

 

Won’t I gain body fat?

 

There have been a bunch of studies to look at short term carbohydrate overfeeding. The one I always come back to is Acheson 1988, which found that the human body has a glycogen storage capacity of approximately 15 g/kg body weight, allowing for a gain of around 500 g before excess carbohydrates begin contributing to an increase in body fat mass. Once glycogen stores are saturated, large carbohydrate intakes are managed by high carbohydrate-oxidation rates and significant de novo lipid synthesis. In other words, you can keep eating carbs until your glycogen is full and basically overflowing, and only then will you begin a process called de novo lipogenesis.

 

The graphic below demonstrates that on day 4 and 5, where carbohydrate intake was dramatically increased, did not result in much body fat gain.  Either the excess calories from carbs were stored as glycogen or the amount of carbohydrates oxidized to provide the body energy increased.  One thing to be careful of is that when you are overeating carbohydrates in this way, any dietary fat you consume will be stored as body fat very quickly, so it is important to not eat too much added fats during the carb loading phase. (Acheson 1988)

 

Burning Carbs vs Fat 

 

When we perform exercise, energy is derived from a few substrates, namely carbohydrates and fats. The relative burning of fat and carbohydrate during exercise can vary substantially and depends on exercise type and intensity (Van Loon 2001).

 

Unlike body fat, which seems like an endless source of energy, there is a limit to the amount of carbohydrates that the human body can store in skeletal muscle and the liver as glycogen. What is glycogen? It's a string of simple glucose molecules stuck together, easily deliverable to working muscles. As discussed, most people can store around 300-700 grams of glycogen in the muscles. A smaller person is likely to have a smaller storage capacity as the amount of storage correlates with muscle size. Thus, the more muscle mass you have, the more glycogen you can store. Similarly, more glycogen is stored in the larger leg muscles than in the smaller upper body muscles. Some glycogen is also stored in the liver, around 60-100g, which can be shuttled throughout the body but is primarily used for essential bodily functions like operating the brain and organs.

 

The amount of carbohydrates burned per minute varies based on the relative intensity of the exercise . Let's consider bipedal locomotion as the first example: i.e., walking, jogging, running, and sprinting. On the easier end of the spectrum (think long walks on the beach), we're burning almost entirely fatty acids. On the hardest end (think running for your life from a bear), we're burning almost entirely carbohydrates. You’ve maybe heard that for most exercise sessions lasting less than 60 minutes, we really do not require any exogenous carbohydrates. 'Exogenous' here means something we consume during exercise, like a gel (Precision Hydration) or liquid (Gatorade).

 

Why don't we need to consume anything? We have enough glycogen storage to complete the session without additional intake. Let’s consider an example of Athlete A who weighs 70kg and runs 15 km in 1 hour, with an approximate glycogen storage capacity of 500g (425g in the body, of which 300g is in the legs and 75g in the liver). Using the well-known formula for energy expenditure in running, we can estimate the approximate energy requirements for running for an hour:

 

Estimated Energy Requirement  = 70kg * 1 kcal * 15 km = 1050 kcal

 

Let’s assume this intensity is close to running from a bear for Athlete A and they require 95% of the energy to come from glycogen to satisfy the energy demands.  So this Athlete A needs 

 

95% * 1050 ~= 1000 kcal from glycogen 

 

How much glycogen is 1000 kcal, well glycogen is approximately 4 kcal per gram.  So our athlete needs 1000/4=250g of carbs.  If they have 300g in the legs and 75g in the liver, then they clearly have enough energy stored onboard to finish the 15km. 

 

Now let’s consider Athlete B who is also 70 kg and trying to finish a full Ironman in 11h10 using a 1h10 swim, 6 hour bike and 4 hour marathon (including 10 min for T1/T2 in those splits). Assume athlete B can oxidize 100g per hour at 11h10 Ironman intensity.  For simplicity across the 3 sports let’s also assume they are burning an average of 800 kcal per hour. 

 

Estimated Energy Requirement  = 800 kcal * 11 = 8800 kcal

 

For this athlete, IM intensity is somewhere near the middle of long walks on the beach and running from a bear, let’s say they are burning 60% of the energy from carbohydrates to exercise at the intensity of 800 kcal per hour.  

 

60% * 800 ~= 480 kcal from glycogen per hour 

60% * 8800 ~= 5280 kcal from glycogen for the race

5280/4= 1320g of carbs to fuel the entire race!

 

If Athlete B has a similar glycogen capacity to Athlete A then we can assume they have a storage capacity of 500g.  If they can only store 500g but need 1320g, what do we do? Consume exogenous carbohydrates during the race of course.  Because we cannot easily fully deplete glycogen I will assume that really there are at most 400g of carbohydrates available for use of the 500g, since the body will hold some back.  Thus we can estimate the fueling requirement as:

 

1320g - 400g = 920g of exogenous carbs needed

 

This is actually not that much since it is around 83g/hour, which is well under the athlete's ability to oxidize carbohydrates of 100g per hour!  How this could be consumed during the race is quite straightforward.  In terms of a basic plan this is what I would do, even without carbohydrate loading. 

1. 30 minutes before the Swim Start - 50g of carbs from gatorade (50g cumulative total)

2. 10 min before the Swim Start - 30g of carbs from PH gel (30g + 50g = 80g cumulative total)

3. 90g per hour on the bike (6 * 90g = 540g + 80g = 620g cumulative total)

4. 75g per hour on the run (4 * 75g = 300g + 620g = 920g total!!)

 

Thus Athlete B is able to meet their carbohydrate needs without even having to go over 90g per hour!  When carbohydrate loading becomes more important is when the carbohydrate requirement increases due to the intensity increases, thus increasing the rate of carbohydrate oxidation and decreasing the rate of carbohydrate absorption (Purdom 2018).

 

For the final example, let’s consider Athlete B again but this time they want to do the same Ironman in 10 hours as a 1h swim, 5h15 bike and 3h45 run.  To accomplish this Athlete has to operate at a higher intensity then when they did the race in 11h10, perhaps about 10% more energy per hour and this will require a higher rate of carbohydrate oxidation as well, let’s say 66% vs 60% in the 11h10 case.  In addition at this intensity their ability to absorb carbohydrates decreases from 100g to 90g per hour. Next, let’s calculate the carbohydrate requirements for this 10 hour effort: 

 

Estimated Energy Requirement  = 880 kcal * 10 = 8800 kcal 

(WOW it’s the same energy to go the same distance…who would have thought )

66% * 880 ~= 580 kcal from glycogen per hour 

Or 

66% * 8800 ~= 5800 kcal from glycogen for the race

5800/4= 1450g of carbs to fuel the entire race!

1450g - 400 = 1050g of exogenous carbs needed  or (105g per hour)

 

105g per hour is above the 90g oxidation ability of Athlete B at 10 hour IM pace!!  If they can only oxidize 90g/hour (or 900g over the entire race) and they require 105g/hour (1050g over the entire race), what happens?  First, and most likely is bonking or slowing down considerably. If you have ever done a full Ironman or spectated, it is very common to see people jogging very slowly or even walking. That is because at this intensity they are burning mostly fat (think long walks on the beach) and therefore their body can effectively supply the substrate needed to continue moving forward. Another option (and hence the purpose of this blog) is to increase the baseline glycogen storage capacity.  If somehow they could increase their legs ability to store glycogen by 50% then they would be able to store 300g  + 50% * 300g [150g] = 450g in their legs).   Now the equation for exogenous carbohydrate intake looks like:

 

1450g - 400 - 150g  = 900g of exogenous carbs needed  or (90g per hour)

 

Now Athlete B has enough energy to complete the Ironman in 10 hours given the energy demands per hour, the rate of carbohydrate oxidation, and the rate of carbohydrate absorption in their body!  Thus, using this strategy, we can see that Athlete B would be able to race faster (10h vs 11h10) without improving their fat oxidation rate or increasing their carbohydrate absorption rate.  

 

To get an idea of how many carbs you may need to finish an Ironman, first you need to be able to estimate how long the race will take you, you can read about how to do that on my other recent blog https://www.precisemultisport.com/blogs/estimate-your-full-ironman-finishing-time.

 

My Ironman Carb Loading Protocol 

 

Now that we’ve gotten through some science and hopefully you have an understanding of the background of why we do it, let me actually provide some practical implementation for you.  Generally we see numbers like 8-12g/kg for 48 hours to carb load.  I’ve found these amounts to be highly effective.  I want to break down what exactly I do, what has worked well, and what has not worked well, including some horror stories. 

 

First, it is important to know your approximate weight.  It does not need to be exact but within a few kg should be good enough. My day to day weight is around 72.5kg and I highly recommend that you DO NOT weigh yourself during the last few days before a race (if the number on the scale carries any emotional weight for you).  In my bodybuilding and powerlifting days I got up to 88kg and down to 68kg so I am not really so concerned about the number on the scale but I think it is not really smart to concern yourself with your bodyweight right before a big event, so I really recommend against weighing yourself.  On a side note, I feel like we live in a time period of information overload where data is provided to us without concern for its impact on our psychology.  For this reason I personally do not wear my Garmin watch outside of running or open water swimming!  I have no idea what my HRV is, my stress, my sleep, my resting heart rate, or the myriad of other things it claims will impact my ability to perform on race day. NO, JUST NO!   I can make a separate blog post on the metrics I do track and how I actually use them but long story short, probably don’t weigh yourself. 

 

So, I am 72.5kg and I need to carb load for 2 days at 8-12g/kg.  Since I eat a generally high carbohydrate diet, I usually try for the upper end of that range of 10-12g/kg. That means I am trying to eat 725g to 870g per day.  In total let’s say its 1600-1700 grams of carbs for the 2 days prior to the event!

First you may be thinking that is a lot, and yes it is, especially if you have not been training as much.   Some common concerns I’ve heard from people is that if they eat too much the night before the race their heart is racing and they cannot sleep.  This is a significant possibility that we need to be aware of.  The best way to get around this is a few fold.  First, the last massive carbohydrate meal you should eat probably should be by 3pm the day before the race. You can still eat after that but it should be normal amounts of food, like a normal portion of pasta or rice for dinner.  Second, during the noon to bedtime period of the final day, you should be relaxing of course but also plan to take a few 15-20 minute walks. This serves a few purposes like increasing insulin sensitivity, digestion, and reducing pre race nerves.  Third, I recommend a cold shower to lower your body temperature.  As you overload on carbs, a normal response for the body is to increase thermogenesis to burn off some of the excess calories. This is manifested through increased body temperature or fidgeting/restlessness.  A cold shower can help decrease heart rate and increase dopamine. Last, do not eat stuff you are not used to eating, especially in the final day of the noon to bedtime period. I will talk more about this shortly, but as you get closer to the end of the carb load, you should aim to consume the most tried and true foods you have used during training for recovery, intra workout, or even for carb loading prior to a long training day. 

 

T-2 days (2 Days before the race)

 

Day 1 of the carb load will be a full rest day for me! How much you train prior to an endurance event is very individual. No tapering plan works for everyone.  For me personally, if I am doing an Ironman I prefer to have a full rest 2 days out and very light training the day before.  If it’s a marathon I like to do a 90 min ride 2 days before and take the day before fully off! You have to experiment what kind of tapering strategy works for you.  This day will also be an important day for sleep because you probably won't sleep as well the night before the event. For me this usually means going to bed by 9pm the night before (I guess we can call that Day 0) but getting up somewhat early on this Day 1. Oversleeping will impair my ability to fall asleep the night before the race, so I usually get up by 530am.  9pm-530am is my typical sleep schedule anyway.  

 

Starting with breakfast around 6am I will consume food similar to what I would eat if I wa going to be heading out on a 2+ hour training ride. For me this is usually 150g of carbs in the form of a bagel, oatmeal, fruit, or combination of them.    I typically like to stay active on Day 1 of the carb load even if I’m not training.  This is usually more about handling race nerves but also light movement helps stimulate appetite. I will plan to eat again at 9am but this meal will be a bit smaller, around 100g of carbs.  At noon I will have a larger meal.  This meal is important to note because here is the last time I include some more fibrous vegetables like beans or broccoli.  I still want to keep some fiber in my diet up to this point to keep digestion moving.  So lunch will be something healthy and pretty voluminous like a buddha bowl, burrito, pasta + side of veggies or something like that, and I will try to make this a large meal of around 1000 kcal and 200g of carbohydrates.   3pm will be a smaller meal, and I will aim for dinner at 6pm.  This will be another large meal but here I will be very cautious about what types of vegetables I eat, if any.  For me I am usually ok to eat carrots but definitely not beans, peas, or corn haha.  So I can have pasta with red sauce and some carrots for around 200g of carbs.  Last meal will be something light like cereal or plant based ice cream around 730pm.  Then I will go on a walk, and try to be in bed by 830pm and asleep by 9pm.   Like the night before, this night of sleep is very important but I try to get up pretty early, like around 4am. This is because I want to be tired the night before the race when going to bed on day 2.  Summary of day 1 meals and timing:

 

T-1 days (Day before the race)

 

For day 2 I want to break it down between the morning and afternoon.  The afternoon is perhaps the most important part of the entire carb loading phase and it needs special care.  First let me describe the morning which is straightforward as it’s more or less identical to the morning from Day 1.   The main difference is I will increase the amount of food I eat during the 9am meal as I am going to reduce the total intake after 3pm. At 900am and 1200pm I have the two largest meals of the day, roughly 400g of carbs within a 3 hour period. Wow ya it’s a lot of food but also early enough where I can first take a nap or NSDR (non sleep deep rest) at 9am and then take a walk after my 12pm meal. Note that I consume the last bolus of protein for lunch and second breakfast, this is because protein is harder to digest and will increase thermogenesis.  I usually put plant based butter or small amounts of oil on my bread and pasta as it makes the food taste better and improves digestion.  Do not overdo it though as it may contribute to increases in body fat!  This should not be a primary concern but the main issue is eating too many fats will decrease your appetite for carbs! The last meal for me is cereal and ice cream because it is very easy for me to digest and I use it before and after training very frequently.  The last thing you eat before you wind down for bed should be something you enjoy and that does not cause you any stomach discomfort whatsoever.

Race Day (T-0 days)

 

I am not going to discuss my race day fueling strategy, I will leave that for a separate blog post.  Here I will discuss the pre race fueling as an extension of the carb loading phase.   Race morning I usually am awake by 4am, assuming a 7am start time.  Once I wake up I have my normal pre workout meal that I’ve had through the training blocks leading up to this and similar to what I ate the day before.  For me this is usually 150g of carbs from oatmeal, 2x bagels, or cereal.  All of those are similar for me in terms of digestion and energy. In transition I will bring a few things with me (1) clif bar (2) gatorade bottle (3) gel w/ caffeine (or caffeine tablet). 90 min before the race I will eat the clif bar, then 30 minutes prior to the race I will have the gatorade (usually the 28oz bottle which contains roughly 50g of carbs.  5 minutes before I will have the gel  (PH30) and caffeine.  This puts my pre race carbohydrate intake around 230g (all before 7am).

 

Summary: 

 

In this blog, I covered the topic of carbohydrate loading for endurance events such as Ironman Triathlon. I explored carbohydrate loading (carb loading), a strategy that emerged in the late 1960s, which focuses on boosting carbohydrate consumption before an event to maximize glycogen storage in muscles. This technique, scientifically backed, has shown to increase glycogen stores by up to 50%, helping delay fatigue and enhance overall performance.

 

I unpack the science behind carb loading, highlighting how a high-carb diet boosts insulin sensitivity and the enzymes needed for glycogen synthesis. Drawing from my personal experiences and success with this method in seven full-distance triathlons and extensive endurance training, I share my approaches and insights. My discussion also includes the intricacies of carb loading, such as sodium loading and leveraging caffeine to increase glycogen uptake, and I address common concerns like weight gain and fat storage.

 

Moreover, I shed light on the dynamics of burning carbs versus fat during physical activity. I went through some examples explaining circumstances when the body's limited glycogen storage capacity can become an issue and the necessity of carbohydrate consumption during prolonged events. I provided a detailed walkthrough of my personal carb loading protocols, offering guidance on meal planning and timing to optimize glycogen storage for peak performance. Through this comprehensive guide, I aim to offer a useful reference for myself and fellow endurance athletes, and I eagerly invite feedback and discussions on diverse strategies and experiences.

 

References: 

Acheson, K. J. (1988). Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man. The American Journal of Clinical Nutrition, 48(2), 240-247. https://doi.org/10.1093/ajcn/48.2.240

 

Bergström, J., & Hultman, E. (n.d.). A study of the glycogen metabolism during exercise in man. PMID: 6048626. https://doi.org/10.3109/00365516709090629

 

Brooks, G. A., & Mercier, J. (1994). Balance of carbohydrate and lipid utilization during exercise: the “crossover” concept. Journal of Applied Physiology, 76(6), 2253–2261. https://doi.org/10.1152/jappl.1994.76.6.2253

 

Empfield, D. (2022, December 12). About Respecting IRONMAN's History. Slowtwitch.com. Retrieved December 10, 2023, from https://www.slowtwitch.com/Opinion/About_Respecting_IRONMAN_s_History_8589.html

 

Hearris, M. A., Hammond, K. M., Fell, J. M., & Morton, J. P. (2018). Regulation of Muscle Glycogen Metabolism during Exercise: Implications for Endurance Performance and Training Adaptations. Nutrients, 10(3), 298. https://doi.org/10.3390/nu10030298

 

Hingst, J. R., & Wojtaszewski, J. F. P. (2018). Exercise-induced molecular mechanisms promoting glycogen supercompensation in human skeletal muscle. Molecular Metabolism, 16, 24-34. https://doi.org/10.1016/j.molmet.2018.07.001 

 

Holloszy, J. O. (1998). The regulation of carbohydrate and fat metabolism during and after exercise. Frontiers in Bioscience, 3, D1011-27. https://doi.org/10.2741/a342 

 

Murray, B., & Rosenbloom, C. (2018). Fundamentals of glycogen metabolism for coaches and athletes. Nutrition Reviews, 76(4), 243-259. https://doi.org/10.1093/nutrit/nuy001 

 

Loureiro, L. M. R. (2021). Coffee Increases Post-Exercise Muscle Glycogen Recovery in Endurance Athletes: A Randomized Clinical Trial. Nutrients, 13(10), 3335. https://doi.org/10.3390/nu13103335

 

Purdom, T., Kravitz, L., Dokladny, K., & Mermier, C. (2018). Understanding the factors that effect maximal fat oxidation. Journal of the International Society of Sports Nutrition, 15, Article 3. https://doi.org/10.1186/s12970-018-0207-1

 

Sims, S. T. (2007). Sodium loading aids fluid balance and reduces physiological strain of trained men exercising in the heat. Medicine & Science in Sports & Exercise, 39(1), 123-130. https://doi.org/10.1249/01.mss.0000241639.97972.4a 

 

Van Loon, L. J. C. (2001). The effects of increasing exercise intensity on muscle fuel utilisation in humans. The Journal of Physiology, 536(Pt 1), 295–304. https://doi.org/10.1111/j.1469-7793.2001.00295.x