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The best supplements for endurance athletes

Post by: Gaby VillaOctober 24, 2022

What are the most effective supplements for triathletes and runners?

For many athletes, it’s hard to think of nutrition without supplements. Unfortunately, the use of supplements across the athletic population is significantly larger than the number of proven effective supplements. That’s why here’s a summary of those supplements with enough evidence of enhancing performance for endurance athletes. 

As an endurance dietitian, I think of supplements as the ‘cherry on top. It doesn’t matter how many cherries you put on your cake, it is half-baked, and some key ingredients are missing, neither the taste nor consistency will be appealing. Relying on supplements to make up for a poor diet is the same. Without the nourishing environment of a solid nutrition and training foundation, most supplements will be useless. 

Sports foods

Products such as sports drinks, energy gels, chews, bars and electrolyte mixes fall within this category. 

The purpose of these products is to supply the athlete with a convenient form to consume a particular nutrient. In many cases, this nutrient is carbohydrates. 

Since endurance athletes rely on carbohydrates as their primary fuel source, these supplements are very relevant. Some key aspects to consider when choosing these products are:

  • Amount of carbohydrates per serving. 
  • Amount of calories per serving. 
  • Type of carbohydrate used (e.g. single or multiple transportable carbohydrates) 
  • Flavour and palatability 
  • Individual athlete preference. 

Suggested use: 

  • Consume 30-60 grams of carbohydrate per hour for activities of up to 2.5 hours. 
  • Consume up to 90 grams of carbohydrate per hour for activities longer than 2.5 hours. 

Events that benefit the most:

  • Events with a longer than 1-hour duration. 


  • For about 60g per hour intakes, include products with multiple transportable carbohydrates. 
  • Review the list of ingredients if you are gluten or fructose intolerant. 


Caffeine is a well-known stimulant with well-established benefits in sports performance. For endurance, caffeine supplements support alertness and decrease perceived effort. Additionally, caffeine promotes fatty acid oxidation helping the body use fat as an energy source. 

Suggested use:

  • 3-6 mg/kg of body weight, consumed 60 minutes before the activity and lower doses of 3 mg/kg or less during the exercise with a carbohydrate source. 

Events that benefit the most:

  • All 


  • More is not better. Larger doses of caffeine do not have an increased effect and are more likely to have a negative impact by increasing the likelihood of side effects. 
  • Caffeine affects sleep. If you are exercising in the evening, re-consider if the benefit outweighs the cost of not supporting adequate recovery due to a lack of quality sleep. 
  • If you do not react well to caffeine, avoiding its inclusion during exercise is better. 


Dietary nitrate enhances nitric oxide availability. This, in turn, supports exercise performance by improving muscle economy, mitigating fatigue and positively impacting cardiorespiratory performance. 

Supplementation with nitrate has been associated with improvements of 4-25% in exercise time to exhaustion and 1-3% in time trials with less than 40 min duration. 

Suggested use:

  • 300–600 mg of nitrate (up to 10 mg/kg or 0.1 mmol/kg) or 500 mL beetroot juice or 3–6 whole beets within 90 min of exercise onset
  • Consider multi-day dosing, e.g., six days of a high-nitrate diet before the event.
  • High nitrate-containing foods include leafy green and root vegetables, including spinach, rocket, celery and beetroot. 

Events that benefit the most:

  • Events with 2h or less duration. 


  • 500 ml of beetroot juice before a race can cause significant gastrointestinal distress in some athletes. Some beet-root concentrates and “shots” have been developed as an alternative. 
  • Dietary nitrate supplements mildly lower diastolic and mean arterial blood pressure, which may be an issue for those with low blood pressure, orthostasis, or at risk of hypotension. 

Final remarks 

By now, you may be wondering, “is that it?”. “Why does my supplement shop has many more items than you just mentioned?”. 

Unfortunately, the world of nutrition supplements is inundated with products that rarely offer the benefits listed on their labels. Many of these products go to market with little to no evidence of their efficacy, putting the athlete’s wallet and, most importantly, their health at risk. 

Remember, always consult with your health or nutrition professional before using any supplement and only consume products that have been batch tested for banned substances. 



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Len Hartley

Previously during Ironman distance events I had issues with hydration and fuelling resulting in a few subpar performances on the run. After speaking to a few other triathletes as well as my coach I decided to contact Gaby at IntensEATfit to get help in identifying and solving these issues to improve my overall performance. While working with Gaby we uncovered that I wasn’t fueling my training sessions well enough, I wasn’t practicing fueling through training enough to condition my stomach to take onboard the required amount of carbs and through testing that my fluid and salt loss was well above average. 

Gaby was great at explaining how these things impact my performance and it was a surprise to find out exactly how much carbohydrate and fluids it takes to successfully fuel and Ironman training & racing. Gaby instilled the importance in training nutrition, and we worked on my nutrition plan weekly allowing my body to get used to the amount of carbs it was taking on board, optimizing the plan to get the best result. This enabled one of the best training blocks I have completed and set me up for a great race in Cairns where I had a strong run to PB by over 10 mins on a challenging course.

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