Long runs, high mileage, and repeated glycogen depletion place heavy demands on your body during marathon training. Runners need a reliable strategy for fueling and hydration to sustain performance across weeks of training and on race day.
A consistent, high-quality diet always comes first. But targeted supplements can provide additional support before, during, and after intense training blocks and races.
The challenge? The supplement market is crowded with products promising performance gains. In reality, only a few have consistent evidence behind them.
Here's what the research suggests about the supplements most commonly used by marathon runners.
Key Takeaways
- Common supplements for marathon runners include electrolytes, carbohydrate gels, caffeine, nitrates (such as beetroot), and ketone supplements. Each supports a different aspect of endurance performance.
- Electrolytes help replace minerals lost through sweat, carbohydrates provide quick fuel, caffeine may improve alertness and perceived effort, and nitrates may improve endurance efficiency.
- Ketone supplements may provide an additional fuel source alongside glucose, which some athletes explore for long-duration performance.
1. Electrolytes for Hydration and Endurance
Long runs get sweaty. And sweating removes both water and electrolytes from your system, especially sodium. Electrolyte supplements help replace those minerals and support hydration during longer efforts.
Most contain sodium along with smaller amounts of potassium and magnesium, which support fluid balance and normal muscle function during endurance exercise. Sodium plays the biggest role because it helps the body retain fluids during prolonged sweating.
Many runners begin incorporating electrolyte drinks or tablets once a run pushes past 60–90 minutes, particularly in warm conditions or during high-mileage training blocks.
2. Carbohydrates and Energy Gels
Carbohydrates are still the main fuel during marathons. But as glycogen stores drop over long distances, fatigue can begin to build. That's when many runners reach for carbohydrate gels, chews, or sports drinks for quick fuel.
Research suggests that consuming carbohydrates during endurance exercise can help maintain blood glucose levels and support steady energy. Runners often aim for about 30–60 grams of carbs per hour during races or long training runs.
However, carb fueling isn't perfect. Larger amounts of sugar at once may not work well for everyone and can sometimes lead to gastrointestinal discomfort. Many athletes explore ways to combine carbs with other fuel sources rather than relying solely on sugar.
3. Nitrates (Beetroot) for Endurance Efficiency
Dietary nitrates, most commonly consumed through beetroot juice, have become popular among endurance athletes striving for performance gains.
Nitrates convert to nitric oxide in your body, a compound that helps relax and widen blood vessels. This may improve blood flow and allow muscles to use oxygen more efficiently during exercise.
Some studies suggest that beetroot supplementation may improve endurance outcomes, such as time-to-exhaustion, though results vary between individuals and race distances. Runners typically experiment with beetroot juice before workouts or races to see whether it helps their pace feel more sustainable.
4. Caffeine for Alertness and Lower Perceived Effort
Caffeine blocks chemical signals in your brain associated with fatigue, which can increase focus and reduce perceived effort during endurance exercise. Some research also suggests caffeine may encourage your body to use more fat for energy early in a run, helping conserve glycogen for later miles.
Many runners consume caffeine before or during races through coffee, gels, or sports drinks. But tolerance varies widely. Some athletes feel jittery or experience stomach discomfort at higher doses, which is why you should always test caffeine strategies during training rather than on race day.
5. Ketone Supplements for Dual-Fuel Energy
Exogenous ketones add another lane to training and race fueling.
Ketone-IQ contains R-1,3-butanediol, which your body converts into ketones after absorption. Those ketones can circulate in your bloodstream and may be used as energy during training and races.
Unlike endogenous ketones (produced by the liver during periods of low carbohydrate availability), exogenous ketones are consumed directly to raise blood ketone levels.
In a randomized, placebo-controlled study using Ketone-IQ in trained participants, supplementation elevated blood ketone levels compared to placebo and was associated with higher average and peak power output during repeated sprint efforts, along with lower fatigue index scores. These findings suggest that, in specific high-intensity training contexts, ketones may play a role in how the body sustains output across repeated efforts.
Participants consumed carbohydrates as part of the testing protocol, reinforcing that ketones can be used alongside typical fueling strategies. They may provide an additional fuel source that both muscles and the brain can draw on as the miles add up.
6. How Runners Think About Timing and Stacking
Rather than relying on a single supplement, many runners use different inputs at different points in training or racing based on how they work in the body.
Before a run, ingredients like caffeine or nitrates are often used to support alertness and blood flow. During longer efforts, carbohydrates and electrolytes help maintain energy availability and hydration. For extended sessions or later in a race, some runners incorporate additional fuel sources, such as ketones, alongside carbohydrates.
Timing and combinations vary depending on the athlete, the intensity of the session, and environmental conditions. Many runners test approaches during training to find what works best on race day.
7. What to Look for in Marathon Supplements
Endurance athletes often look for products that are:
- Well tolerated during long training sessions and races
- Easy to digest while running
- Supported by sports nutrition research
- Compatible with other race fueling strategies
Hydration, circulation, and alertness all play different roles in endurance performance. If you're curious about how an additional fuel source might fit into that strategy, explore Ketone-IQ next.
FAQs
What supplements do marathon runners take?
Marathon runners commonly use electrolytes, carbohydrate gels, caffeine, nitrates (such as beetroot), and sometimes ketone supplements. These products support different aspects of endurance performance, including hydration, fueling, circulation, and alertness during long training sessions and races.
Does caffeine help marathon performance?
Caffeine may help marathon performance by increasing alertness and reducing perceived effort during endurance exercise. Many runners consume caffeine before or during races through coffee, gels, or sports drinks. Because tolerance varies widely, athletes usually test caffeine strategies during training rather than on race day.
How do runners avoid stomach issues from energy gels?
Runners often prevent stomach issues from energy gels by spacing carbohydrate intake and taking gels with water. Practicing race-day fueling during long training runs can also help the digestive system adapt to absorbing fuel during exercise, a process commonly referred to as "gut training."
Can you combine caffeine and ketone supplements?
Yes. Caffeine and ketone supplements can be used together because they influence performance in different ways. Caffeine primarily affects alertness and perceived effort, while ketones provide another potential fuel source for the body during endurance exercise. As with any fueling strategy, athletes typically test combinations during training.
Are ketone drinks better than energy gels?
Ketone drinks and energy gels serve different roles in endurance fueling. Energy gels provide carbohydrates, which are the primary fuel during intense running, while ketone drinks provide compounds that the body can convert into ketones. Some athletes explore combining the two as part of a dual-fueling strategy.
How do runners avoid hitting the wall in a marathon?
Runners often avoid "hitting the wall" by maintaining steady fueling throughout a race. This usually includes consuming carbohydrates, staying hydrated with electrolytes, and pacing appropriately. Some athletes also explore strategies that add another fuel source, such as ketone supplements, alongside carbohydrates.
Learn More
- How to Run Faster: Mental and Physical Techniques
- Tapering to Achieve Peak Race Day Performance
- Side Stitch: Unraveling a Runner's Worst Enemy
- Do Exogenous Ketones Improve Focus and Mental Performance?
