What are the best Intra workout supplements for endurance athletes?

Joana Rego


What you eat or consume before and even during your workout is crucial for fuelling your workout and maximising your performance throughout.

This is a very important detail, especially if you are on a serious diet to cut weight (if you follow a low-protein or low-carb diet, for example), if you decide to train in a fasted state, or if you're doing a very strenuous workout (e.g. more than 2 hours per day).

In these specific situations, or simply because you want to guarantee a continuous supply of nutrients to achieve your maximum growth and performance, having an intra-workout supplement is a very wise attitude, because it will help you prevent muscle breakdown, soreness and fatigue.

They aren't a very popular category, and they often fly under the radar, which is unfortunate because they have plenty of benefits for beginners, pros, and enthusiasts as well.

In fact, even if you think that you always give your best, you know that you can achieve perfection, right?

Endurance training tips

If you are an endurance athlete, you need carbohydrates as a primary source for quick energy. The more intense and longer the duration of exercise, the more important it is to ensure carbohydrate intake is sufficient.

You also need fluids, or your body will have a hard time performing at its best. If you're exercising for more than 60 minutes in hot, humid conditions for example, sports drinks may help because they give you carbs and sodium, as well as fluids.

Glutamine increases football player's endurance

Sports drinks are also a good choice, preferable to water, if you play team sports like football or rugby, especially when the temperature and humidity are high and you sweat a lot.

Gels are concentrated forms of carbs. They can help long-distance cyclists and runners get some quick fuel during exercise.

If you're exercising to lose weight, stick to water or a "lighter" version of these intra-workout supplements with fewer carbs and calories, but keep in mind that you have to be careful about your pre- and post- workout nutrition in terms of carbohydrates needs and the duration of your physical activity, if you don't want to “hit the wall”.

What can these supplements do for you?

  • Provide a boost of energy;
  • Give you additional endurance;
  • Improve your power while you're training;
  • Help minimise the catabolism of muscle tissue;
  • Promote mental clarity and strength output;

What can be inside an intra-workout formula?

The right amount of BCAA

Branched-chain amino acidsBCAAs - Supplements Prozis (BCAA; leucine, isoleucine, and valine) don't need to be processed by your liver, so after absorption they enter your bloodstream directly to be picked up by your muscles.

A few studies showed that the consumption of BCAA (30 to 35% leucine or more), before or during exercise, may prevent or decrease the net rate of protein degradation, improve both mental and physical performance and diminish muscle glycogen degradation and the depletion of muscle glycogen stores.

This happens because physical exercise causes the breakdown and oxidation of BCAA. Providing BCAA to working muscles will prevent your body from catabolising the working muscle itself. As the training session goes along, the BCAA in circulation are used by the muscle and their concentration in the blood decreases. As they compete with tryptophan for the passing through the blood-brain barrier to the brain, more tryptophan passes if their concentration is reduced. Tryptophan is also an amino acid, used in the brain for the synthesis of serotonin, a neurotransmitter that induces relaxation and pleasure but also fatigue.

Another advantage is the property of boosting the immune function by helping reverse glutamine loss.


L-Glutamina - ProzisIt is during training, when sudden catabolic stress is placed on your body and you begin to use up your glycogen stores, that your BCAA and glutamine stores begin to become compromised.

Glutamine, like other alpha-amino acids, is involved in regulating protein synthesis and breakdown. However, there's far more to it than that. Glutamine significantly affects BCAA metabolism, gut barrier maintenance, normal immune function, glucose formation, water transport, neurotransmission, and more.

Good carbohydrate sources

Maltodextrine - ProzisStudies show that muscles can store enough glucose for up to 120 minutes of high-intensity exercise – after that the drop in available fuel leads to a drop in performance that ends with ‘the bonk’.

As we saw in the article “Nutrition for beginners: the facts about carbs”, energy-containing foods are now classed by their position on the glycaemic index (GI), so the production of energy from carbs is affected by the type of carbs you're taking in. You can control the rate at which your energy supply flows by eating certain types of carbohydrates.

Concerning the kind of carbs you should consume during the endurance training or event, the main purpose of this nutrient is to ensure rapid delivery of glucose. These carbs that are rapidly digested so that their glucose is quickly fed into the bloodstream have the highest glycaemic index (high GI foods score over 70), so that the higher the GI, the quicker blood glucose levels rise.

In summary, the best carbohydrates included in an intra-workout supplement are fast delivery and high GI, like maltodextrine and dextrose that you can easily take in via a good isotonic sports drink or gel, and by eating bars as well.

Other substances that are commonly included in this type of products are caffeine, vitamins, minerals and L-carnitine, among others.

Intra-workout supplements are designed for fast absorption, so use them the moment you feel fatigued, and to promote recovery and hydration. Most of them can be consumed before and after workouts (or anytime really).

Just choose the perfect ally for your workout, and nothing will stop you from now on!


  1. Kim, D.-H., Kim, S.-H., Jeong, W.-S., & Lee, H.-Y. (2013). "Effect of BCAA intake during endurance exercises on fatigue substances, muscle damage substances, and energy metabolism substances". Journal of Exercise Nutrition & Biochemistry, 17(4), 169–180. http://doi.org/10.5717/jenb.2013.17.4.169
  2. Humberto Nicastro, Claudia Ribeiro da Luz, Daniela Fojo Seixas Chaves, et al., “Does Branched-Chain Amino Acids Supplementation Modulate Skeletal Muscle Remodeling through Inflammation Modulation? Possible Mechanisms of Action,” Journal of Nutrition and Metabolism, vol. 2012, Article ID 136937, 10 pages, 2012. doi:10.1155/2012/136937
  3. Gualano AB, Bozza T, Lopes de Santos P, Roschel H, Dos Santos Costa A, Luiz Marquezi M, Benatti F, Herbert Lancha Junior A, "Branched-chain amino acids supplementation enhances exercise capacity and lipid oxidation during endurance exercise after muscle glycogen depletion", J Sports Med Phys Fitness 2011 Mar; 51 (1) : 82-8
  4. Blomstrand E., "Amino acids and central fadigue", Amino Acids. 2001;20(1):25-34.
  5. Vinicius Fernandes Cruzat, Maurício Krause and Philip Newsholme, "Amino acid supplementation and impact on immune function in the context of exercise" Journal of the International Society of Sports Nutrition 2014, 11:61 doi:10.1186/s12970-014-0061-8
  6. Beelen M, Cermak NM, van Loon LJ. "Performance enhancement by carbohydrate intake during sport: effects of carbohydrates during and after high-intensity exercise". Ned Tijdschr Geneeskd 2015;159:A7465.
  7. Zhang Y, Kobayashi H, Mawatari K, Sato J, Bajotto G, Kitaura Y, Shimomura Y, "Effects of branched-chain amino acid supplementation on plasma concentrations of free amino acids, insulin, and energy substrates in young men." J Nutr Sci Vitaminol (Tokyo). 2011; 57(1): 114-7
Joana Rego


Graduated in 2006 with a Master's degree in Pharmaceutical Sciences at the University of Porto, Portugal. Worked as a pharmacist for 6 years, during which she discovered her preference for the fields of sports nutrition, food supplementation and dietetics. She's passionate about sports and she's currently responsible for the management of Men's Physique PRO, Bikini Fitness, and Bodybuilding athletes.


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