At 51 years old, Johannesburg-based ultra runner Donovan Shirley continues to push the limits of endurance performance. Two months ago, he set a new South African soil backyard ultra record by completing 43 laps (288 km) in a Backyard Ultra.
Last weekend, Donovan took on an even bigger challenge: running a double Comrades Marathon within 24 hours. Starting at 5 p.m. on Saturday, he first completed the route in reverse in 11 hours and 7 minutes before lining up for the official 85.77 km Comrades “Up Run” on Sunday 5 a.m. Despite already having 90 km in his legs, he finished the race in 11 hours and 15 minutes, comfortably inside the demanding 12-hour cut-off.
The Get Back Up Challenge
In total, Donovan covered 175 km in less than 24 hours. But the challenge was about more than endurance alone.
“The idea was born out of raising awareness and to start conversations around mental health,” said Donovan. “I wanted to highlight that we can do hard things…. And with the right team around us, we can find the strength and the courage to get back up. For some people a hard thing is a 175 km endurance event… for some it might be finding the strength to get out of bed in the morning.”
Completing a challenge of this magnitude requires more than determination alone. Careful preparation, a dedicated support team, and a well-executed nutrition strategy fueled by Amacx were all essential to helping Donovan reach the finish line.
Importance of carbohydrates
During ultra running, energy production is predominantly aerobic, with carbohydrates and fats serving as the main fuel sources. Importantly, carbohydrates require less oxygen to produce the same amount of energy as fat, making them a more efficient fuel source during exercise. In fact, aerobic energy production from carbohydrates is approximately 7% more efficient than fat. When the duration or intensity of an effort increases (e.g., climbs, surges, faster race sections), the importance of carbohydrates becomes greater. Carbohydrates are not only the main fuel source for your muscles, but also for your brain. When blood glucose levels drop too low, cognitive performance can suffer, potentially leading to poor pacing or fueling decisions.
There is one crucial point to consider: the body’s carbohydrate storage capacity is limited. Carbohydrates are stored in the body in the form of glycogen, mainly in the muscles and, to a lesser extent, in the liver. This glycogen stock is, as it were, the body’s fuel tank. That is why starting with a full tank and continuing to consume carbohydrates during the race is essential to sustain race pace all the way to the finish line.
Tapering: the final preparation phase
In the final week(s) before an ultra-endurance event, training volume decreases while the focus shifts toward arriving recovered and in top condition at the start line.
“In the final days before the challenge, the focus shifted from fitness to freshness.” — Donovan
Alongside a reduced training load, nutrition played a key role in Donovan’s final preparation for his double Comrades challenge. In the week before the race, he consumed two daily servings of Amacx Beet Shots, while also taking two servings of Amacx Cherry Juice+ to support recovery.
In the final 48 hours before the event, Donovan followed a carbohydrate loading protocol with Biscoff Hot Cross buns, mashed potato, pizza and pasta as his go-to foods. Donovan also included the Amacx Energy Drink to increase his carb intake without feeling constantly full, ensuring his glycogen stores were fully maximized for race day.
For a more in-depth explanation about tapering nutrition and supplementation strategies, check out our tapering blog: Nutrition and Supplements During Tapering – How to Approach It
Race day nutrition
Structured fueling = consistent performance
Going into the race with a structured fueling and hydration plan is crucial, rather than depending on whatever nutrition is available along the way.
Carbohydrate strategy
For any single-stage ultramarathon that does not last multiple days, the priority is to consume sufficient carbohydrates per hour rather than trying to replace every calorie burned. In fact, research shows that a one-day energy deficit does not meaningfully impair performance, but underfueling carbohydrates definitely does.
For Donovan, the aim was to consume 90 g of carbohydrates per hour, which equals 3 Amacx Energy Line products. His nutrition plan combined a variety of Amacx products including 1 Energy Fruit Chew, 1 Drink Gel and 1 sachet of Energy Drink per hour, every hour. The key was not to chase a perfect number every single hour but to adapt his intake to the demands of the course. During higher-intensity sections, carbohydrate intake could be pushed toward the higher end. On easier, flatter sections, intake could be temporarily scaled back.
Hydration strategy
His crew played a key role in keeping his hydration strategy on track by ensuring his flasks were regularly refilled, helping him avoid unnecessary stops. During the Down run, this was straightforward, with a flask of Amacx Energy Drink (Lemon or Forest Fruit) prepared every hour, alongside additional water during the hottest part of the day. On the Up run, it got a bit harder as he was relying on carrying his own nutrition. He used a 500 ml soft flask, refilling it hourly and mixing in an Amacx Energy Drink sachet. By alternating flavours throughout the effort, he helped prevent flavour fatigue.
“The crew was like a formula 1 pit crew. It was stop, fill and go!” — Donovan
Key tip: Your hydration plan should be flexible. Weather conditions and pace can change during an ultra.
Caffeine strategy
Because Donovan started his challenge in the evening and immediately ran through the night, caffeine was introduced relatively early in his race strategy. While large caffeine doses before the start of an ultra are generally avoided to prevent going out too hard too early, research shows that consuming small, repeated doses of caffeine (1-2 mg/kg BW) are a practical and well-tolerated approach during ultramarathons.
During the night section of the race, Donovan used one Amacx Energy Drink Gel Cola Caffeine (75 mg caffeine) every 3rd hour to help maintain alertness. Research also shows that caffeine consumed later in the race, or when fatigue starts to build, may help reduce the perception of effort and support performance.
“Caffeine is great at masking fatigue. Late at night when the body is meant to be sleeping was a great time to start taking caffeine. I also started the Up run with a caffeine gel and then planned to finish the last 30 km alternating between normal gels and caffeine gels.” — Donovan
How to reduce gastrointestinal risk during an ultramarathon?
One of the biggest nutritional challenges during ultramarathons is managing gut issues. They can severely limit carbohydrate intake and are one of the main reasons ultra runners are forced to slow down or fail to finish.
As an experienced ultrarunner, Donovan was already used to high carbohydrate intakes. However, without a proper strategy, every runner can experience gut issues. To minimize Donovan’s risk of gastrointestinal problems during the race, we focused on six practical strategies:
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Train the gut – the gut is trainable, just like the muscles
In the weeks leading into Comrades, Donovan repeatedly practiced his carbohydrate intake to train his gut to better tolerate, absorb, and utilize large amounts of carbohydrates while running.
This included:
- Gradually increasing carbohydrate and fluid intake during training
- Testing fluid intake in different weather conditions
- Testing nutrition under realistic race conditions, including nighttime sessions
Key tip: Make it personal. Race nutrition should always be tested, adjusted, and practiced in training.
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Start protecting the gut 48 hours before the race
Race nutrition does not start at the starting line. In the final 48 hours, Donovan reduced his intake of high-fiber and high-fat foods to lower the chance of gut discomfort during the race.
Key tip: Include food that you are familiar with.
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Optimize your hydration plan
The majority of gut issues are solved with a proper hydration plan. Even mild dehydration increases the risk of gut discomfort.
Key tip: Collect sweat rate data during training to put your plan together.
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Avoid overloading the gut
Avoid high fiber, fat, and protein sources during the race, as these can slow digestion and increase the risk of bloating or other gut issues.
Key tip: Focus on easy-to-digest carbohydrate sources that can deliver energy without sitting heavily in the stomach.
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Keep overnight fueling simple
Running overnight increases the risk of gut issues as digestion slows down.
Key tip: During these hours, easy-to-digest carbohydrates and consistent fluid intake become even more important.
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The golden rule: nothing new on race day
Race day is for executing a practiced strategy, not experimenting with a new gel, drink, or bar because it ‘looked good’ at the expo.
Key tip: Every product Donovan used during Comrades had already been tested extensively in training.
Flavour fatigue
In ultra-endurance racing, many athletes gradually lose their appetite or become tired of the same flavours and textures, which can ultimately lead to underfueling. For Donovan, finding products he genuinely enjoyed, and could continue consuming deep into the race, was an important part of the strategy. This is where the flexibility of the Amacx Energy Line played an important role. Because every product within the line provides 30 g of carbohydrates, Donovan could easily vary flavours, textures, and product types to reduce flavour fatigue while still staying on target with his carbohydrate intake.
“Mix it up as much as possible. Change the texture, change the flavour. Go sweet, go savory. I never took the same gel consecutively in this challenge.” — Donovan
Alongside his sports nutrition strategy, Donovan also included normal foods during the race to create more variation. The key was to replace products smartly: if he swapped out a gel, he chose a food option with a similar carbohydrate intake.
“Bananas are my grab-and-go staple and boiled potatoes with lots of salt. I gave myself a lot of options at my aid stations because you don’t know what you are going to crave during a long run.” — Donovan
For endurance athletes struggling with flavour fatigue, neutral-flavoured products like our new Amacx Turbo Gel Neutral can also be a useful strategy later in the event.
