Carbohydrate loading has been around since the 1960s but has evolved over time as more research has been published. In the 1960 it was believed that you had to do a glycogen depletion phase first in order to have carbohydrate loading work, but that has since been proven incorrect. Modern carb loading consists of simply eating increased amounts of carbohydrates in the days leading up to an event/race.

Current research recommends eating 10-12g carbohydrates per kg body weight in the 36-48 hours before a race. 

For our 70kg runner, this would mean eating 700-840g of carbs per day (2800-3360 calories from carbohydrates!). Yes this is a lot and in order to eat that much carbs, we'd need to decrease the amount of fat and protein in your diet. It's recommended to decrease fat consumption and maintain moderate protein consumption. To eat this much carbs, you also want to think about eating less fiber filled foods. White rice, bread, pasta, cereal, pancakes, bagels, and sports drinks can be the easiest sources to eat. Fruit and fruit juices can also be consumed. 

Race morning, it is recommended to eat 1-4g carbohydrates per kg body weight, ideally 4 hours before race start. 

For our 70kg runner, this would mean eating 70-280g carbohydrates. Again limiting fat and fiber is recommended and moderate amounts of protein. 

A proper carb load will lead to significantly increased glycogen storage in muscles and the liver. Carbohydrate loading as described above can double glycogen stores in the body which can drastically improve race performance, especially in ultramarathon events. 

A 2017 study by Belavy et al. showed that runners had more hydrated lumbar discs and higher glycosaminoglycan levels, both signs of healthier spines, than more sedentary people. This seems positive...

A 2020 study by Mitchell et al. showed in middle-aged men that long term endurance running reduced age-related decline in lumbar intervertebral disc health. The study also showed that those who had been running for more years and running more miles per week had healthier discs than those running less. More good news...

​In 2024, Shu et al. did a comprehensive qualitative review of 2019 studies in existing literature to look at how running affects intervertebral discs because many believe running has negative impacts on spinal health. They concluded that running causes short-term temporary compression of the discs, squeezing water out of the discs, but long-term running has an overall positive effect on spinal disc health. Again, this is sounding very positive, but what effect would running have on people who already have some degenerative in their lumbar discs? Would running be harmful them? Or would running still be beneficial to their discs? 

That is the question Samanna et al. looked at in a new study published in March 2026. This study had people (50% woman - yay research including women!) complete a 12 week run/walk program and did MRIs on their lumbar spines before and after the 12 week intervention. Some of the findings were: 

• run/walk program was found to positively impact disc health
• the people who started with more degenerative saw the most positive improvements 

It also seemed that the people who saw the most benefit ran moderate distances and at moderate speeds and running on soft surfaces seemed to be positive. 

All of these studies show what most runners feel - running makes us feel better in many ways including our backs. So whether you already have back problems, or want to prevent them, running can a be a great way to do that. And all of us trail runners look to be doing wonderful things to help improve our spinal disc health and prevent future back problems. 

​Traditional medicine and physical therapy often say Haglund’s is caused by hereditary factors such as high arches, tight Achilles tendons, and walking on the outside of their feet. In runners it is also said to be an overuse injury. First, it’s important to understand the body responds to stimulus and all those factors are a response to our environment rather than genetic.
 
Haglund’s always occurs on one heel and not both (at least at the same time and same intensity) just like all other injuries, which means that the injury is caused not by use or overuse but imbalances in the body left to right.

Below I will walk you through 3 simple tests to help you feel and understand what is causing your Haglund's deformity and pain. 

​If you experience heel pain and have a Haglund’s deformity on your right heel, that means your right foot, ankle, knee, hip, and shoulder are working and moving differently than your left. And yes, you heard me right, your shoulder has as much to do with the heel pain as your heel does. Why? Because the body is a unit (I’ll walk you through some experiments to feel this in a minute). Doing things including surgery, orthotics, physical therapy, and shoe changes, do nothing about the cause of the problem. This means the pain and Haglund’s can return. There are a number of famous ultra trail runners who have had multiple surgeries just to have Haglund’s return again and again. If you don’t eliminate the cause of the problem, the problem will keep reoccurring.

​Typical treatment plans include changing mileage and intensity, NSAIDS, icing, heel lifts and heel pads, casting, dry needling, shockwave therapy, ART (active release therapy), myofascial release, PRP (platelet rich plasma), stem cell injections, orthotics, exercises and stretches for the lower leg and foot, and surgery. These all are treatments for the symptom, but do not address the cause. They might offer temporary relief but won’t lead to long-term relief and ability to fully return to running pain free.
 
Only posture alignment therapy that corrects the imbalances in your foot, ankle, knee, hip, spine, and shoulder fix the cause of the problem.

​Different posture imbalances can cause Haglund’s deformity and pain including: thoracic flexion and rotation; lateral spinal flexion including scoliosis; pelvic rotation and elevation; femur internal or external rotation or valgus or varus stress; knee flexion or hyperextension; ankle/foot eversion, inversion, pronation, and supination.
 
Why and how do these posture imbalances lead to Achilles imbalance and eventually Haglund’s deformity and pain? All of the above posture imbalances will lead to a change in hip flexion and extension which the body will have to figure out how to move the body forward when running and those compensations the body must do to continue running can lead to changes in Achilles load and movement patterns. (These compensatory movement patterns can lead to Haglund's deformity, but also Achilles tendinopathy, heel bone spurs, plantar fasciitis (or plantar fascipothy), and other foot and ankle pain symptoms.)

Below are several tests and experiments you can do to see what posture imbalances might be causing your Haglund’s deformity:

1. Weight test: take off your shoes and socks and stand barefoot on a hard surface. Step up and down in place several times, and then stand relaxed with your eyes closed. Notice the weight distribution in your feet. Do you have more weight in one foot than the other? Is the weight more towards the front or back of one foot than the other? Is the weight more on the inside or outside of one foot? Many people with Haglund’s will notice that the weight is more towards the front and outside of the foot that has Haglund’s deformity. Why is that? When you excessively load the front and outside of your foot, you are putting an abnormal and excessive stress on your posterior leg muscles and Achilles tendon. This abnormal stress will slowly overload the Achilles attachment on the posterior heel and lead to a thickening of the bone, swelling, and pain. The only way to correct this and get back to running pain free is to correct your posture imbalances that are causing you to abnormally load your foot.
2. Balance test: Stand barefoot on a hard surface and look down at your feet and get them parallel and pointed straight ahead (this will often feel pigeon toed for many people). Lift one knee up to hip height so your knee is bent at 90 degrees and try to balance on your other leg for 10 seconds. Then align your feet again and switch sides. Which leg were you more stable on? Many people will notice they are less stable on the side with the Haglund’s deformity. The instability in your hip and leg are leading to a less stable foot/ankle complex as you walk and run and this is causing abnormal and excessive movement at the foot/ankle which is causing stress on your Achilles and leading to the Haglund’s deformity. The only way to eliminate this stress and get back to running pain free is by correcting your posture imbalances that are leading to the instability.
3. Gait test: while barefoot, walk across a hard floor several times at a normal pace and notice your foot strike. Basically, notice where you land on your heel, how the weight rolls through your foot, and where you push off from. Many people with Haglund’s will notice they land more towards the outside of the affected foot, roll through the outside of the affected foot, and push off more towards the outside of the foot. This is because their femur is often externally rotated and lacks proper internal rotation, foot pronation, and dorsiflexion. This faulty movement pattern leads to an overloading of the Achilles because of a lack of internal rotation of the femur and tibia and dorsiflexion of the ankle.

Earlier I talked about how your shoulder is as much a cause of the problem as your foot is. Now is the time to test that. After performing the above tests, write down what you felt – your findings. Now repeat all three tests, but this time with a small but powerful change. Interlace your fingers together, put your hands behind your head, and pull your elbows back hard. Hold this position as you repeat all three tests. What was different in each of these tests with your hands behind your head? Almost everyone will feel their weight distribution is more balanced and even in the first test. Most people will notice their balance is improved in the second test, especially on the unstable side. And most people will notice their gait is much more symmetrical and even – meaning they land more in the center of the heel, roll through the center of the foot, and push off all five toes more evenly. You might also notice you have less pain and discomfort walking with your hands behind your head. Why is this? The improvements happen because putting your hands behind your head helps to improve your shoulder imbalances, which in turn improve your spinal alignment, which balances your pelvis and hips, and allows your legs and feet to work more closely to how they are designed.

​We all know it’d be pretty awkward to run ultras with your hands behind your head, so I’m not going to advice that, but what I do advise is getting a free 30-minute video posture evaluation online by me to help you understand what posture imbalances throughout your body are causing your uneven loading of your foot so we can correct them and fix the underlying cause of your Haglund’s deformity and get you back running pain free.

Do you suffer from Haglund's deformity? Comment below about what you learned from these 3 simple tests. 

My goal is to make is easy for you to calculate how many carbs (and other nutrients) are you consuming with your current plan and be able to modify/improve your nutritional plan to optimize training and racing performance and recovery.

Related articles that are must reads to go along with this:
How to get high carbs per hour. 
How to Maximize Race Day Performance and Minimize GI Distress. 
​Carbs are King/Queen! 

Please let me know what other nutrient details you'd like to see listed and any products or foods you would like me to add to the lists. I will create a separate list for electrolyte drinks/supplements and recovery nutrition soon also. 

Step one is start looking at different foods and energy products to see how many carbs they contain per serving. Make a list of them so it's easy to calculate carbs per hour. 

Step two is look at the list and figure out which foods/products you know you already like and your GI system handles well. Figure out which foods/products you can eat per hour to reach your carb goal. 

If you're newer to high carb fueling, start with a goal of getting 60g carbs/hour. Some examples are below. ​

Let's say you like Tailwind Endurance Fuel and usually use 1 scoop per half liter (17 oz) bottle and you drink about one bottle per hour. This means from Tailwind you are getting 25g carbs/hour. You also like GU energy gels and typically eat 1 per hour. This would give you an additional 23g carbs/hour for a total of 48g carbs/hour. 

With the goal of getting 60g carbs/hour, we need to find a way to get an additional 12g carbs/hour. To do this you could eat:

• 2 Clif Bloks an hour which would give you 16g carbs
• 1 Honey Stinger waffle which would give you 19g carbs
• 2 Fig Newtons which would give you 21g carbs
• add a half scoop more Tailwind to your bottle for an additional 12g carbs

You typically just drink water and eat a PB & J sandwich every hour. This would give you 32g carbs per hour. This is half your goal of 60g carbs per hour. 

Some ideas on how to reach your goal are:

• Start drinking Skratch Labs Hydration Sports Mix 1.5 scoops per 17oz bottle each hour for an additional 28g carbs per hour
• Eat one Strykr 30 gel per hour for an additional 30g carbs per hour
• Eat one Maurten Gel 100 per hour for an additional 25g carbs per hour
• Eat a 1/4 cup rainins per hour for an additional 29g carbs per hour

If you're an experienced athlete with high carb fueling, but looking to push the limits to maximize performance, some examples are below: 

You currently use Skratch Super High-Carb Hydration Drink Mix at a concentration to give you 50g carbs per 17 oz bottle (3.5 scoops) and drink one bottle an hour. You also eat one Precision Fuel PF 30 gel per hour for an additional 30g carbs per hour. This currently gives you 80g carbs per hour. 

Some ideas to increase your carbs per hour to 100g per hour are: 

• Eat a Strykr Gel50 instead of the Precision Fuel PF 30 which would give you an additional 20g carbs per hour
• Switch to using Precision PF 90 gel and eat half of it each hour for an additional 15g carbs per hour
• Mix your Skratch High-Carb drink mix to a concentration of 100g carbs per hour (7 scoops) and then you don't have to eat the Precision PF 30 gel

You currently use Maurten Drink Mix 160 which gives you 39g carbs per hour and eat two Maurten Gel 100's an hour which are 25g carbs each. This gives you a total of 89g carbs per hour currently. 

You can increase your carbs per hour with any of these ideas: 

• Switch to Maurten Drink Mix 320 and Maurten Gel 160 to increase your carbs to 159g carbs per hour
• Switch from two Maurten Gel 100 an hour to two 6d Sports Nutrition Ultra Gels an hour to increase your carbs to 129g carbs per hour
• Switch to Neversecond C90 Drink mix and two Neversecond C30 Energy Gels an hour for a total of 150g carbs per hour

How many grams of carbs do you currently consume during long runs and races? 

What are your go-to foods/drinks during long runs and races? 

I've always liked looped course runs more than out-and-backs, but there is something extra special about running all the way around a mountain. I love seeing the mountain from all sides noticing the differences in terrain and plants and how the light hits each side of the mountain differently from sunrise to sunset. When I finish, I always feel like I did something special. 

Doing the same circumnavigation at different times of year and on different years is also very enjoyable. Spring snow fields, avalanche lillies, and trillium; summer rushing rivers, lupin, and paintbrush; autumn colors and ripe huckleberries and blueberries. Seeing the year to year changes of a circumnavigation from winter storms, summer forest fires, landslides, and plant growth reminds us that change is the only constant, but all change can be beautiful. 

I know not everywhere has circumnavigations, especially around volcanoes, but if you ever have the chance to run around a mountain I highly recommend it. Below are some of my favorites in the Yamakiasham Yaina or Cascade Range (most are yearly traditions): 

The Wonderland Trail is a 93 mile trail that completely circumnavigates Tahoma (Mount Rainier) with about 25,000ft of elevation gain. I recommend taking the Spray Park option because of much better views of the mountain and epic wildflowers, snow fields, and scree. This can be done in a single push (less than a day for FKTers or a day and a half for mortals), but I recommend doing it in 3 days so you get to enjoy all the views and scenery during daylight. It can be done either direction and starting from any of the three major trailheads - Longmire, Mowich Lake, or White River. You can fastpack it over 2-3 days by bringing some lightweight camping gear and lots of food or better yet talk a friend(s)/family member into crewing it for you. That way you get to run each day with only food/water for the day and your crew drives your camping gear from campground to campground. 

The Timberline Trail circumnavigates Wy'east (Mount Hood) and typically runners start at Timberline Lodge. Timberline Lodge is a great place to start from because there is plenty of parking, bathrooms, food, and lodging should you need it. You can run the loop in either direction, but counterclockwise is more popular. I've also done the loop starting at Ramona Falls Trailhead which is nice because you end on a long downhill instead of long uphill, but it does add mileage and a little vert to a pretty long hard day. The classic Timberline Trail loop is about 39 miles and 10,000 ft elevation gain. 

The Loowit Trail circles Mount Saint Helen's and on paper doesn't look that hard - 29 miles and 7,000ft elevation gain - but in reality can feel much harder. How hard it is all depends on the weather. The thing with the Loowit trail is a large portion is very exposed to the sun and there are long stretches without water. On a cool, overcast day it's not bad, but on a hot, sunny day it can be brutal. Trail runners often start at June Lake Trailhead or Climbers Bivouac trailhead and most run clockwise. Loowit is one of my favorites because of the variety of terrain - forest, meadows, lava fields of boulders, washouts, loose pumice, and the moon-like Plains of Abraham. 

The Three Fingered Jack loop is about 22 miles with about 3,000ft elevation gain and makes for an easier late spring/early summer circumnavigation. I've always started at Santiam Pass and ran clockwise as you get the climbing done early but it does leave you with a long exposed section that can get hot and dusty without a lot of water. I love to add a little out and back on Canyon Creek Trail and Glacier View Trails up to see the mountain goats and the turquoise glacier lake. This addition will add about 4 miles and 1300ft depending on how far up you go. 

Broken Top loop has a couple options, but is about 22 miles and 4,000ft elevation gain. I start at Three Creeks and head up Tam McArthur Rim trail to go clockwise. There's some fun scree scrambling as you approach the high point and after a quick descent you're at beautiful turquoise No Name Lake (the highlight of the loop). Fast runnable trails await as you run towards Green Lakes before a return 5 miles through a burned area. In July 2023 there were hundreds fallen trees across the trail making for slow going. 

​Examples of overuse injuries are:

Most overuse injuries are blamed on doing "too much too soon" or "training load errors". While this makes sense at first, with further examination it becomes clear this isn't the whole picture. ​

Let's examine "overuse" injuries common to runners like patellofemoral pain syndrome, Achilles tendonopathy, shin splints, stress fractures, and iliotibial band syndrome. These injuries often occur on only one side of the body. How can "too much too soon" be the cause of a unilateral injury when both legs were running the same miles? If running too many miles too soon was the cause of a runners Achilles tendonopathy, then both legs would be affected the same and often they are not. This means that something else is contributing to the Achilles tendonitis on the injured side. ​

I believe that the often unidentified factor that is contributing to the overuse injury showing up on one side of the body is posture imbalance. ​Good posture is defined by Florence Kendall as "that state of muscular and skeletal balance which protects the supporting structures of the body against injury or progressive deformity, irrespective of the attitude (erect, lying, squatting or stooping) in which these structures are working or resting." When the bones and joints of the body are no longer held in good postural alignment, any activity from sleeping, to sitting, to standing, to running is causing increased stress and wear and tear on certain tissues of the body which will eventually lead to pain and damage. All biomechanical imbalances are caused by posture imbalances. 

A common posture imbalance that can cause one sided running injuries is having a slightly stronger and more stable hip compared to the other. This will cause very slight changes in stride length, stance time, and subsequent imbalanced forces on muscles and connective tissues. For instance if your right leg is slightly stronger than your left leg you will spend more time loading your right leg which could lead to patellofemoral pain syndrome on your right knee from the extra load or iliotibial band syndrome from the extra load on your right hip. In this instance you will also try to unload your weaker left hip quicker which could mean you are pushing off with your left foot harder leading to Achilles tendonitis on your left side. ​

What about things like stress fractures? Surely they can't be from posture imbalances, right? Stress fractures, whether a metatarsal stress fracture, tibial stress fracture, or sacral stress fracture are all caused by posture imbalances. Again all of these happen on one side of the body, which by definition means they are caused by imbalances in load and movement left to right in your body. 

To use the same example as above; if your right leg is stronger and more stable than your left leg, this could lead to a right sided sacral stress fracture from the excessive and uneven loading. This same imbalance could also lead to a left sided tibial or metatarsal stress fracture because the instability in your left hip will lead to poor knee, ankle, and foot biomechanics which will lead to non-optimal loading of the bones in your left leg. 

While blaming too much too soon as the cause of overuse injuries is easy, it is not the whole picture. Posture imbalances play a part in most if not all overuse injuries. Correcting your posture and muscle imbalances will improve your biomechanics which will help you prevent overuse injuries. If you are already injured, correcting your posture will help you heal faster and get back to your sport sooner. 

I am a big proponent of high carb intakes during training and racing and research backs this up also. Recently I ran the 28k at Big Alta by Freetrail and Daybreak Racing in beautiful Marin County, California and wanted to use my race as an example of high carb intake during racing. ​

First of all, the Big Alta is an amazing weekend of trail running and I would highly encourage you to go race or watch next year. 2024 was the first year of the race and it amazing. Race weekend was so fun with the 50k on Saturday and the 28k on Sunday. I watched some friends race the 50k on Saturday and hung out at some aid stations and the finish line and it was such a great vibe. Sunday I raced the 28k with a bunch of friends and had a blast. 

Freetrail and Daybreak brought in Mountain Outpost to do the livestream of both races, had Dylan Bowman or Tim Tollefson on the finish line mic most of the weekend, and so many spectators were there to watch the action. The whole weekend was beautiful weather, had a great mix of fast pro trail runners there running and watching, and grassroots feel to the race. Anyone who was there will tell you the Big Alta had the best vibes! ​

Sunday I raced the 28k and since I'm a midpack runner and hadn't been putting in a lot of miles or training, I just planned to run with friends, go out easy, slow run the ups, enjoy the views, and see how I felt after the second big climb and maybe push the final descent because I'm a downhill person (the reason I love mountain biking, roller coasters, fast cars, and anything exciting!). 

If you have not tried high carb intake during racing, I would highly recommend it. Experiment with different products and foods to see what works for you. You want something that tastes great, doesn't give you GI distress, and is easy to consume. Practice on long training runs and interval workouts and then doing it during racing will be second nature and easy. 

Let's talk about how to flourish in a carb world. First we want to eat a relatively high carb (CHO) diet to prevent low energy availability (LEA), relative energy deficiency in sport (REDs), and low carbohydrate availably (LCA) which all have negative health and performance outcomes (read more about this here) and  keep our muscle glycogen stores topped up. Daily CHO needs for an ultra-runner are 6-12g/kg body weight. The lower end for athletes running an average of an hour a day and the higher end for athletes averaging 4+ hours of running a day. 

We want to make sure we spread our CHO consumption out throughout the day so we don't spend hours in low carbohydrate availability. This means carbs with breakfast, lunch, dinner, and snacks between meals (which all of us ultra runners should be having). 

During endurance exercise, especially over 90 minutes, we should be consuming CHO. How much CHO should we consume during exercise? The American College of Sports Medicine position stand is to consume 60g CHO/hour for exercise lasting 1-2.5 hours and 90g CHO/hour for exercise lasting longer than 2.5 hours. Research has shown that consuming more CHO (up to 120g CHO/hour) can be even more beneficial in terms of performance, reduced ratings of perceived exertion, improved mental state, decreased post-exercise muscle damage (DOMS), and improved recovery. 

Multiple transport carbohydrates are the most efficient way to consume and absorb CHO which means consuming a mix of glucose and fructose. You can read more about this in my article about Race Day Nutrition.

Cyclists have been pushing higher and higher CHO intakes during training and racing and have seen performances increase. Ultra runners are following suit and experimenting with higher CHO consumption during training and racing. Over the years, I've gone from consuming 60g CHO/hour to 75g CHO/hour to 90g CHO/hour to 120g CHO/hour and not only felt better in training and racing but performed better and all without gastrointestinal (GI) distress. 

If you have not experimented with higher CHO intakes during longer training runs and races, I highly recommend it. The gut is highly trainable, and fairly quickly, but it does take practice. 

​Costa RJS, Miall A, Khoo A, Rauch C, Snipe R, Camões-Costa V, Gibson P. Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Appl Physiol Nutr Metab. 2017 May;42(5):547-557. doi: 10.1139/apnm-2016-0453. Epub 2017 Mar 22. PMID: 28177715.

​Jentjens RL, Jeukendrup AE. High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling exercise. Br J Nutr. 2005 Apr;93(4):485-92. doi: 10.1079/bjn20041368. PMID: 15946410.

​Jentjens RL, Moseley L, Waring RH, Harding LK, Jeukendrup AE. Oxidation of combined ingestion of glucose and fructose during exercise. J Appl Physiol (1985). 2004 Apr;96(4):1277-84. doi: 10.1152/japplphysiol.00974.2003. Epub 2003 Dec 2. PMID: 14657042.

Nutrition and Athletic Performance. Medicine & Science in Sports & Exercise 48(3):p 543-568, March 2016. | DOI: 10.1249/MSS.0000000000000852

​Stellingwerff T, Cox GR. Systematic review: Carbohydrate supplementation on exercise performance or capacity of varying durations. Appl Physiol Nutr Metab. 2014 Sep;39(9):998-1011. doi: 10.1139/apnm-2014-0027. Epub 2014 Mar 25. PMID: 24951297.

​Temesi J, Johnson NA, Raymond J, Burdon CA, O'Connor HT. Carbohydrate ingestion during endurance exercise improves performance in adults. J Nutr. 2011 May;141(5):890-7. doi: 10.3945/jn.110.137075. Epub 2011 Mar 16. PMID: 21411610.

Urdampilleta A, Arribalzaga S, Viribay A, Castañeda-Babarro A, Seco-Calvo J, Mielgo-Ayuso J. Effects of 120 vs. 60 and 90 g/h Carbohydrate Intake during a Trail Marathon on Neuromuscular Function and High Intensity Run Capacity Recovery. Nutrients. 2020 Jul 15;12(7):2094. doi: 10.3390/nu12072094. PMID: 32679728; PMCID: PMC7400827.

​Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro A, Seco-Calvo J, Urdampilleta A. Effects of 120 g/h of Carbohydrates Intake during a Mountain Marathon on Exercise-Induced Muscle Damage in Elite Runners. Nutrients. 2020 May 11;12(5):1367. doi: 10.3390/nu12051367. PMID: 32403259; PMCID: PMC7284742.

​Daily needs for CHO for an ultra-runner are 6-12g/kg body weight. The lower end for athletes running an average of an hour a day and the higher end for athletes averaging 4+ hours of running a day. Protein (PRO) while not used as a primary energy source is essential to maintain muscle mass and cellular function and repair. Daily needs for PRO for ultra-runners are 1.2-2.0g/kg body weight per day. Again, the lower end is for athletes exercising less and the high end is for athletes exercising more and creating more weekly muscle damage. Most ultra-runners would be safe to consume 1.6-1.8g PRO/kg body weight. 

​It is a good idea to avoid eating a gel or any high-glycemic food in the hour before a race because research has shown that can lead to the release of insulin which can lead to hypoglycemia early in the race. If you want to eat something in the hour before your race, it’s best to eat a low-glycemic CHO, like fructose and avoid high-glycemic CHO like glucose. As soon as you’re running you can start consuming high-glycemic foods and not have those negative side effects. 

​While running, it’s a lot easier on your stomach to digest small amounts of food continuously rather than large amounts infrequently. This means focusing on getting in calories constantly in small amounts. You can eat your calories, drink your calories, or do a combination of both to meet your calorie needs. Getting some food in at least every 20 minutes is ideal. Definitely avoid letting an hour or more go by without eating because then it’s a lot more likely your digestive system will shut down and cause you gastrointestinal (GI) distress and you’ll be much more likely to bonk. Those scenarios are best to avoid. 

There’s a term called Multiple Transportable Carbohydrates (MTC) that describes how glucose and fructose (two types of sugars) are absorbed in the body differently and when we consume both types, we can absorb more calories of CHO per hour than if we only ingest one type of CHO. Glucose is absorbed in the intestine by the sodium-dependent glucose transporter SGLT1, and fructose is absorbed in the intestine by the intestinal transporter GLUT 5 (or recently renamed SLC2A5). Research has shown people on average can absorb 60g glycose and 30g fructose per hour (360 calories from CHO), so it has been standard practice to recommend ingesting food to meet those numbers. Recent research however has shown that another glucose transporter GLUT2 (or SLC2A2) shows up almost instantly in the gut in response to the presence of glucose and allows athletes to absorb more than previously thought. Research has also shown that the gut is highly trainable in as little as two weeks. I’d recommend experimenting with increasing CHO intakes during training in the weeks prior to your race to figure out what amount your body can tolerate. 

​Some sports nutrition products will list glucose or fructose on the label, but many will instead list other names for sugar. To understand what these ingredients mean, here’s a breakdown of the most common carbohydrates in sports nutrition products: 

​Dextrose: another name for glucose
Sucrose: 50% glucose 50% fructose
Maltodextrin: a chain of glucose molecules 
Cane Sugar/table sugar: same as sucrose – 50% glucose 50% fructose
Maltose: two molecules of glucose hooked together
Honey: about 50% glucose and 50% fructose
High Fructose Corn Syrup: about 50% glucose and 50% fructose 
Brown Rice Syrup: 52% malotriose, 45% maltose, 3% glucose. But maltotriose is three glucose molecules and maltose is two glucose molecules, so it is 100% glucose. 

​​Real foods like rice and wheat are mainly starches which break down into glucose. A potato is about 55% glucose and 45% fructose. A banana is about 50% glucose and 50% fructose, as are most fruits. Oreo cookies, gummy bears, Sour Patch Kids, and most candies are made with sugar, dextrose, corn syrup, and/or high fructose corn syrup and will have between a 50/50 to 60/40 glucose/fructose ratio. 

​As you can see, most foods trail runners consume while running will give you a mix of glucose and fructose. The shorter the race is (2-5 hours) the easier most athletes find it to eat just CHO, but as races get longer (6-24+ hours) most athletes find their palate demands things other than sugar, and often a little more protein and fat. At higher intensities it is difficult to digest fat and protein. As intensity decreases, which will naturally happen in longer races (6-24+ hours), it becomes easier for your gut to digest fat and protein. 

​One very promising ingredient in sports nutrition is Highly-Branched Cyclic Dextrin (HBCD) or Cyclic Cluster Dextrin (CCD). HBCD is made by fermenting corn starch to make a molecule of linked glucose units similar to glycogen. HBCD has been shown to decrease gastrointestinal upset, decrease gastric emptying time, decrease rating of perceived exertion, and improve endurance performance compared to typical glucose/fructose mixtures. Many athletes are finding that consuming a portion of their hourly glucose in the form of HBCD decreases GI distress and allows them to consume more CHO/hour. 

​Whether you eat or drink your CHO depends on many factors including ease of consumption, availability, personal preference, gut tolerance, sweat rate, and weather conditions. It is important to have a good estimate of individual sweat rates for different conditions and to make sure you match your water and electrolyte consumption accordingly. In cold and dry weather, you are going to need less water and in hot and humid conditions, more water. I’ll discuss hydration in detail in a future article. 

In summary, to help set yourself up for a great race, make sure you are consuming adequate carbohydrates in your daily diet, pre-race meal, and during your race. Most athletes find they do well by consuming 75+ grams (300+ calories) of CHO per hour, from a mix of glucose and fructose and possibly in the form of Highly-Branched Cyclic Dextrin. As with everything, experiment and practice your nutrition plan well in advance of your race to find what works for you.