Home / What works / Performance and strength
By goal · evidence reviewed on
Which supplements improve training performance
The short answer. What holds up with sources is short: creatine and caffeine, about €1.57 a month at the dose used in the studies. This page lists 6 supplements with evidence for this goal, and 3 sold for it that you do not need.
The four listed here are the ones the ISSN accepts for performance, each for a different kind of effort. Outside their effort range, they do nothing.
† Some links are affiliate links — they do not change the ranking
Some store links are affiliate links: if you buy through them, this site may earn a commission at no extra cost to you. It changes nothing in the ranking: the score is computed beforehand and without reading those links, and products with no affiliate programme appear exactly the same. How it is calculated.
The basics, and what they cost
Creatine
€0.80a month
3 to 5 g a day, every day, whether you train or not.
Cheapest at that dose: Firm Foods Creatina 2 kg (2x 1 kg) from Zumub, €8.95/kg.
Caffeine
€0.76a month
3 to 6 mg per kilo of body weight, 30 to 60 minutes before.
Cheapest at that dose: Cafeína - 500 Comprimidos - 200 mg por Comprimido from Amazon, €0.025/capsule.
€1.57 a month in total, adding up creatine and caffeine at one effective dose a day with the cheapest product that reaches that dose. It is not a medical recommendation or a plan: it is what the evidence-backed options cost today, in the stores this site compares.
The 6 with something behind them
By evidence level and monthly cost
| Supplement | Evidence | What has been measured | Per month |
|---|---|---|---|
| Caffeine3 to 6 mg per kilo of body weight, 30 to 60 minutes before. | Strong evidence86 products compared · best score: Cafeína - 500 Comprimidos - 200 mg por Comprimido from Amazon | Endurance: where it works bestGuest NS et al. ISSN position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021;18:1. Dosis ergogenica de 3-6 mg/kg, 30-60 minutos antes; sin beneficio adicional por encima de 9 mg/kg. | €0.76 |
| Creatine3 to 5 g a day, every day, whether you train or not. | Strong evidence223 products compared · best score: Firm Foods Creatina 2 kg (2x 1 kg) from Zumub | Maximal strength and power: +5 to 15 %Kreider RB et al. ISSN position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017;14:18. | €0.80 |
| Beta-alanine4 to 6 g a day, split into 2 to 4 servings of 1 to 2 g. | Strong evidence36 products compared · best score: Zumub Beta-Alanina 250g (2x 125g) from Zumub | Time to effect: 2 to 4 weeksTrexler ET et al. ISSN position stand: Beta-Alanine. J Int Soc Sports Nutr. 2015;12:30. 4-6 g diarios durante 2-4 semanas; efecto en esfuerzos de 1 a 4 minutos; parestesia como efecto adverso habitual. | €2.68 |
| Carbohydrates30 to 60 g per hour of long continuous effort. Outside that, the day’s food. | Strong evidence113 products compared · best score: Zumub Dextrosa 4kg (2x 2kg) from Zumub | Efforts of 1 to 2.5 hours: 30 to 60 g per hourThomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Med Sci Sports Exerc. 2016;48(3):543-568. 30-60 g/h en esfuerzos de 1-2,5 h y hasta 90 g/h con fuentes multiples por encima de 2,5 h. | no published dose |
| Citrulline6 to 8 g of citrulline malate, or 3 to 5 g if the product is pure citrulline. | Moderate evidence42 products compared · best score: Ecolac L-Citrulina Dl-Malato 2:1 Bote 500 gr from Bulevip | Reps in sets to failure: a few moreKerksick CM et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr. 2018;15:38. Citrulina malato en el rango de 6-8 g por toma en los estudios de rendimiento. | €5.25 |
| Pre-workoutsCaffeine: 3 to 6 mg per kilo of body weight. For 70 kg, between 210 and 420 mg. Beta-alanine: 4 to 6 g a day. | Moderate evidence124 products compared · best score: Beta Alanina en polvo 1000g, 5000mg por porción, Pre Workout para 7 meses from Amazon | Caffeine: muscular strength and endurance: consistent effectGuest NS et al. ISSN position stand: caffeine and exercise performance. J Int Soc Sports Nutr. 2021;18:1. 3-6 mg/kg de peso corporal. | €26.94 |
The 3 they will try to sell you for this
Weak evidence, supplement price
Reviews find no consistent effect. It is listed because it sells, not because it works.
| Supplement | What has been measured | Per month |
|---|---|---|
| BCAABCAAs are three amino acids: leucine, isoleucine and valine. | Muscle protein synthesis: not sustained aloneWolfe RR. Branched-chain amino acids and muscle protein synthesis in humans: myth or reality? J Int Soc Sports Nutr. 2017;14:30. | €2.62 |
| GlutamineGlutamine is the most abundant amino acid in the body and it is used by muscle and gut. | Sports performance: no demonstrated effectKerksick CM et al. ISSN exercise & sports nutrition review update: research & recommendations. J Int Soc Sports Nutr. 2018;15:38. La glutamina aparece entre los suplementos con evidencia limitada o nula. | €2.47 |
| ZMAZMA is not an ingredient: it is a specific formula of zinc, magnesium and vitamin B6 that became popular as a hormone booster. | Testosterone in trained athletes: no changeWilborn CD et al. Effects of Zinc Magnesium Aspartate (ZMA) supplementation on training adaptations and markers of anabolism and catabolism. J Int Soc Sports Nutr. 2004;1(2):12-20. Sin cambios en testosterona ni en las adaptaciones al entrenamiento frente a placebo. | no published dose |
Weak evidence is not fraud. It means the effect does not show up when diet already fills the gap, or that the studies behind it are small, short or paid for by the seller. Each guide says in which specific case it does make sense, which almost always exists and is almost never the case of the person buying it.
Questions about supplements for: performance and strength
Answered with the data on this page
- Which supplements should you take to performance and strength?
- The minimum you can defend with sources is creatine and caffeine, which at the dose used in the studies comes to €1.57 a month buying the cheapest that reaches that dose. Beyond that, this page lists another 4 with evidence behind them, each for a specific case.
- And bcaa, glutamine, zma?
- BCAA, Glutamine, ZMA have weak evidence for this: Reviews find no consistent effect. It is listed because it sells, not because it works. They are sold a lot for this goal and each has its own guide with the sources, so the decision does not depend on what a label says.
- Where do these prices come from?
- From the 4065 products this site collects across 19 Spanish stores, with prices from October 15, 2026. The monthly cost is one effective dose a day for 30 days, with the cheapest product that reaches that dose. The evidence was reviewed on September 4, 2026.
Other goals
The same list, another question