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Supplement Guide for Endurance Athletes

Unless your among the most elite professional endurance athletes, you probably don't have the luxury of choosing any and every supplement you want and therefore need to be selective about what supplements you buy. Just like the world of protein powders, there are plenty of options when it comes to supplements for the average endurance athlete.  So how does one go about Shop for Endurance Supplementsprioritising their endurance supplements? Ultimately it comes down to what’s going to give you the best value for money and greatest benefit to performance. Periodisation of training can also have a bearing on the supplements an endurance athlete might use. This article will provide an overview of the key nutritional and supplement needs of endurance athletes and in so doing provide an guideline on supplement selection.

Nutritional Needs of Endurance Athletes

The first thing to understand about the nutritional/supplement needs of endurance athletes is that they are fundamentally different to those of strength/power athletes. When it comes to endurance athletes, carbohydrates are the primary limiting fuel for exercise and as such much of the general nutrition strategies for endurance athletes are designed to maximise muscle glycogen levels or replenish glycogen in a timely manner. Protein is also important for the average endurance athlete as aerobic exercise still burns muscle tissue, but on average protein needs for endurance athletes are significantly less than their bodybuilding conterparts. As such, this article will start by taking detail look at carbohydrate requirements for endurance athletes.

Carbohydrate Requirements for Endurance Athletes

Because of its importance for optimal performance, an extensive amount of research has been conducted to determine the optimal carbohydrate intake for endurance athletes. These guidelines vary based on the type of exercise the athlete is engaged in and their training/competition regime and goals.

Traditionally carbohydrate intake guidelines have been set based on the notion of ‘replacing’ what is ‘lost’ during exercise. But recent research has taken a more holistic view of sports nutrition by recognising that exercise also serves as an important stimulus or trigger for favourable muscle adaptations. What’s more, these muscular adaptations can be affected by the timing and type of nutrients ingested in proximity to exercise.

Factors Affecting Carbohydrate Requirements

For example research has shown that there may be benefits to restricting carbohydrate intake for a period after exercise or even deliberately conducting training sessions in a glycogen depleted state. This particular philosophy and training approach is commonly referred to as the Train Low-Compete High model, which is discussed in detail in our article on the topic.

Some of the factors affecting carbohydrate intake guidelines for endurance athletes include:

  • Length and intensity of training session
  • Length of time between training sessions
  • Weight of athlete
  • Goals of training session
  • Proximity to competition or race

Carbohydrate intake guidelines for endurance sports can vary depending on the mix of the above factors. For example, professional cyclists competing in the Tour de France are constantly in a race against the clock to refuel because they have to compete on average for 4-5 hours per day over 3 weeks and complete glycogen replenishment can take up to 24 hours. As such, cyclists have to ensure they are taking on carbohydrates regularly, both on and off the bike. However, in cases where an athlete may be undertaking sessions designed to increase fat burning efficiency, a specific effort may be made to reduce carbohydrate both before and during the training session.

In cases where training intensity or performance are paramount, optimal carbohydrate stores are crucial. For example, the International Olympic Committee made the following recommendation in their 2010 Consensus Conference on Nutrition for Sport.

“When it is important to train hard or with high intensity, daily carbohydrate intakes should match the fuel needs of training and glycogen restoration”

The guidelines below provide some basic recommendations on carbohydrate intake for endurance athletes based on their training intensity and volume.

Training Type

Carb Intake/Bodyweight/Day

Low intensity or skill-based activities: Moderate training program for athletes with large BM or energy restriction

3-5g/kg of athlete’s body mass/day

Moderate exercise program (i.e. ~1hr per day)

5-7 g/kg/d

Endurance program (e.g. 1-3hr/d mod-high intensity)

6-10 g/kg/d

Extreme commitment (i.e., >4-5 h/d mod-high intensity exercise)

8-12 g/kg/d

*Burke LM et al. J Sports Sci. 2011; 29 Suppl 1:S17-S27.

Carbohydrate Supplements

As highlighted above, carbohydrate supplements are particularly valuable to endurance athletes in cases where they have less than 24 hours between races or hard training sessions. Under such circumstances, carbohydrate intake requirements are very high (i.e. 8-12 g/kg/d). Consuming this amount of carbohydrate (i.e. ~700g for 70kg individual) is often impractical, simply because of the sheer volume of food one has to consume. In these instances, carbohydrate supplements offer a more convenient and efficient means of reaching target carbohydrate intake. Moreover, there are certain types of carbohydrate supplements that have been shown to be superior for glycogen replenishment.

Far and away, the most researched type of carbohydrate supplement is one sold under the brand name of Vitargo. Vitargo is a highly branched form of amylopectin, which also has a high molecular weight; making passage through the stomach easier than lower molecular weight carbohydrates like maltodextrin. Vitargo has been shown to restore glycogen faster than conventional maltodextrin as well as produce better performance when performing a time trial 2hr after an initial exercise bout1-3.

Protein Supplements for Endurance Athletes

Traditionally the realm of strength athletes; protein supplements also play an important role in the diet of endurance athletes. While accruing muscle mass is not generally an aim for your average endurance athlete, endurance exercise itself does result in a degree of muscle breakdown and damage and in this sense, the right protein supplements can play a vital role.

Because generally speaking, endurance athletes are concerned with maintaining optimal glycogen levels, this can affect the type of protein supplement they chose. It turns out that whey protein hydrolysates are a class of proteins that have been shown to have distinct benefits for both muscle repair and glycogen resynthesis. The specific details of how whey protein hydrolysate can improve endurance adaptations are covered in detail in our article entitled ‘Post Workout Nutrition for Recovery’. Suffice to say that compared to carbohydrate only, consumption of whey protein hydrolysate and carbohydrate results in greater glycogen storage following intense exercise4, 5. What’s more, continued use of whey protein hydrolysate over weeks and months can lead to more efficient use of carbohydrate during exercise6. So for any endurance athlete serious about their protein, be sure to buy a good quality hydrolysed whey protein and use it regularly.

As an aside, protein supplementation can also play a key role in maintaining proper immune function, particularly during times of high-intensity training. For example, a recent study showed that elite cyclists consuming a high protein diet during 1-week of high-intensity training had fewer symptoms of URTI compared to performing high-intensity training with a normal diet7.

Sports Drinks for Endurance Athletes

Sports drinks are an immensely popular category of endurance supplements that are used widely; particularly for longer endurance events such as marathons, triathlons and long distance cycling. Sports drinks provide a source of energy and electrolytes to offset losses during exercise. Without the use of sports drinks during prolonged endurance exercise, the body’s carbohydrate reserves are depleted more rapidly, thus reducing endurance capacity. One of the key issues with sports drinks is the limit on carbohydrate absorption during exercise because of reduced blood flow to the stomach. As a result, much of the research with sports drinks has focused on strategies to increase/maximise carbohydrate absorption.

The main findings of this research have shown that ingesting different types of carbohydrate can significantly increase total carbohydrate absorption. This is thought to be due to the fact that carbohydrates like glucose and fructose use different carriers in the intestine and therefore don’t compete with one another for absorption. Moreover, the combination of glucose and fructose is thought to have a synergistic effect by enhancing absorption of both. A combination of 2 parts glucose to 1 part fructose has consistently been shown to result in the highest carbohydrate absorption rate during exercise8, 9. So naturally any sports drinks that contains this particular combination is a preferred option for endurance athletes. Powerbar are one such company that have a number of energy and hydration supplements that utilise a 2:1 glucose:fructose ratio, which they term C2max.

While numerous studies have shown a 2:1 glucose:fructose ratio to be best for maximising carbohydrate absorption during exercise, there are a significant number of individuals who have what is termed fructose malabsorption16. This typically means that ingesting sports drinks or energy supplements with fructose tends to result in bloating or abdominal discomfort in such individuals. These type of individuals are best suited to use of sports drinks that have little to no fructose content. One example of a low fructose sports drink is BSc Fuel Sports Drink

Energy Supplements for Endurance Athletes

The most popular energy supplements for endurance athletes come in the form of energy gels or 'gu's'. Powerbar Gel that come with a 2:1 glucose:fructose ratio. However, for the most part, the nutritional profile of energy gels are largely the same, with the predominant ingredients simply consisting of water, sugar, sodium, acids and flavouring. Therefore personal preferences for factors such as flavour and gel viscosity largely dictate the type of gel any given endurance athlete will purchase. There are however some gels such as the GU brand that include additional amino acids, albeit at relatively low concentrations.

Ergogenic Aids for Endurance Athletes

Ergogenic supplements are broadly defined as those used for the purpose of enhancing performance. Accordingly they are a very popular supplement category for endurance athletes, but caution is needed as there are a lot of supplements with claims of ergogenic properties that don’t have much science to back them up.  Ergogenic supplements can work via a number of different mechanisms, namely, buffering muscle acidity, improving oxygen utilisation/transport, increasing fat oxidation, decreasing perception of effort etc. When evaluating ergogenic aids in the context of supporting scientific information, there are three noticeable standouts, namely:  

Space in this article does not permit to go into great detail about how each of the above supplements improve performance, but suffice to say each work via different mechanisms and have numerous studies supporting their efficacy for boosting endurance exercise performance. For more detailed explanation on how each supplement works, click each one to read our detailed articles explaining their performance enhancing benefits. Out of these three, caffeine is the most cost-effective supplement, however, beetroot can also be cost effective when using it in the form of beetroot juice. There are a number of other ergogenic aids for endurance exercise that are worth mentioning, namely:

  • Rhodiola rosea13
  • Quercetin14
  • Eleutherococcus senticosus (Siberian Ginseng)15



1. Leiper JB, et al. Improved Gastric Emptying Rate in Humans of a Unique Glucose Polymer with Gel-forming Properties. Scand J Gastroenterol 2000;35:1143–1149.
2. Piehl Aulin K, et al. Muscle glycogen resynthesis rate in humans after supplementation of drinks containing carbohydrates with low and high molecular masses. Eur J Appl Physiol (2000) 81: 346±351.
3.Stephens FB, et al. Post-exercise ingestion of a unique, high molecular weight glucose polymer solution improves performance during a subsequent bout of cycling exercise. Journal of Sports Sciences. 2007;1 – 6.
4. Morifuji M, et al. Post-exercise carbohydrate plus whey protein hydrolysates supplementation increases skeletal muscle glycogen level in rats. Amino Acids. 2010;38(4):1109-1115.
5. Morifuji M, et al. Branched-chain amino acid-containing dipeptides, identified from whey protein hydrolysates, stimulate glucose uptake rate in L6 myotubes and isolated skeletal muscles. J Nutr Sci Vitaminol (Tokyo). 2009;55(1):81-6.
6. Morifuji M, et al. Preexercise ingestion of carbohydrate plus whey protein hydrolysates attenuates skeletal muscle glycogen depletion during exercise in rats. Nutrition. 2011 Jul-Aug;27(7-8):833-7.
7. Witard OC, et al. High dietary protein restores overreaching induced impairments in leukocyte trafficking and reduces the incidence of upper respiratory tract infection in elite cyclists. Brain Behav Immun. 2013 Oct 10. pii: S0889-1591(13)00501-1.
8. Jeukendrup AE & McLaughlin J. Carbohydrate ingestion during exercise: effects on performance, training adaptations and trainability of the gut. Nestle Nutr Inst Workshop Ser. 2011;69:1-12; discussion 13-7.
9. Baker LB & Jeukendrup AE. Optimal composition of fluid-replacement beverages. Compr Physiol. 2014 Apr 1;4(2):575-620.
10. Hodgson AB, et al. The metabolic and performance effects of caffeine compared to coffee during endurance exercise. PLoS One. 2013;8(4):e59561.
11. Bellinger PM. β-alanine supplementation for athletic performance: An update. J Strength Cond Res.2013 Nov 22. [Epub ahead of print]
12. Hoon MW, et al. The effect of nitrate supplementation on exercise performance in healthy individuals: a systematic review and meta-analysis. Int J Sport Nutr Exerc Metab. 2013 Oct;23(5):522-32.
13. De Bock K, et al. Acute Rhodiola Rosea Intake can improve endurance exercise performance. International Journal of Sport Nutrition and Exercise Metabolism. 2004;14:298-307.
14. Kressler J, et al. Quercetin and endurance exercise capacity: A systematic review and meta-analysis. Med Sci Sports Exerc. 2011; 43(12):2396–2404.
15. Kuo J, et al. The effect of eight weeks of supplementation with Eleutherococcus senticosus on endurance capacity and metabolism in human. Chin J Physiol. 2010 Apr 30;53(2):105-11.
16. Riveros MJ, et al. Fructose consumption and its health implications; fructose malabsorption and nonalcoholic fatty liver disease. Nutr Hosp. 2014 Mar 1;29(3):491-9.

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