Whey Protein vs. Plant Protein: Which is Better for Endurance Athletes?
This article is for you if you regularly run, cycle, or participate in hybrid fitness races. If you're weighing whey against plant protein, or wondering if a vegetarian diet can sustain your training, then this article is for you.
1Why Endurance Athletes Should Also Take Protein Seriously
Although endurance training primarily relies on aerobic energy, long sessions and high-intensity intervals still increase muscle turnover. The body continuously renews and adapts tissues through muscle protein synthesis (MPS). MPS initiation requires two conditions: sufficient total daily protein, and adequate leucine per meal (an essential amino acid that acts as the "switch" to trigger MPS).
The International Society of Sports Nutrition (ISSN) recommends 1.4–2.0 g/kg daily for active individuals, and approximately 1.2–1.4 g/kg for endurance athletes (Jäger et al., J Int Soc Sports Nutr 2017; Thomas et al., J Acad Nutr Diet 2016).
Conclusion: Protein is not just for "building muscle," but an integral part of endurance training adaptation.
- Jäger et al., J Int Soc Sports Nutr 2017
- Thomas et al., J Acad Nutr Diet 2016
2Fundamental Differences Between Whey and Plant Proteins
Whey protein, derived from dairy, is quickly absorbed, has a complete amino acid profile, and a high leucine density, thus rapidly increasing blood amino acid levels and strongly triggering MPS. Plant proteins (represented by soy isolate) are digested more slowly and have slightly lower leucine content, but are still complete proteins, providing all essential amino acids.
Both provide the raw materials needed for MPS; the difference lies in "fast versus slow" and "slightly higher versus slightly lower leucine," not "effective versus ineffective."
* Schematic diagram · Data based on product information in the case
- Jäger et al., J Int Soc Sports Nutr 2017
- Morton et al., Br J Sports Med 2018
3The Key is Leucine, Not the Source Label
Research shows that the muscle composition gains from an equal intake of plant protein are comparable to those from animal protein (Messina et al., Int J Sport Nutr Exerc Metab 2018; Hevia-Larraín et al., Sports Med 2021). A controlled study comparing habitual vegetarians and omnivorous trainers even found that a high-protein plant-based diet can equally support resistance training adaptations.
The target leucine intake per meal is approximately 2.5–3 g. For example, a single serving of recovery product: REGO Whey (22 g whey protein) contains 2.8 g of leucine, and REGO Rapid Recovery (21 g soy protein, labeled Vegan) contains 2.5 g of leucine—both meet the target.
* Schematic diagram · Data are quoted values from the article
Key takeaway: If your diet is primarily plant-based, you can add an extra 10–22 g/day to your total protein intake and combine it with leucine-rich foods (such as tofu, quinoa).
- Messina et al., Int J Sport Nutr Exerc Metab 2018
- Hevia-Larraín et al., Sports Med 2021
- Jäger et al., J Int Soc Sports Nutr 2017
4Myth: "Plant protein is incomplete and cannot keep up with training"
* Schematic diagram · Myth vs. Reality
5Conclusion: Focus on Compatibility, Not Just Labels
Both whey and plant proteins can support endurance training; the choice depends on digestive tolerance, dietary preferences, and ease of intake.
Actionable steps:
- First, calculate total intake: Endurance athletes need 1.2–1.4 g/kg daily, spread across 3–4 meals.
- Monitor leucine per meal: 2.5–3 g (approximately 20–40 g of high-quality protein).
- Products as convenient sources: If you want to recover quickly after exercise, consider REGO Whey (22 g whey protein, 2.8 g leucine); if you prefer plant-based or vegan options, choose REGO Rapid Recovery (21 g soy protein, 2.5 g leucine, labeled Vegan). Both are options for post-exercise supplementation. Always consider personal diet and gut tolerance, and test new products during training first.
- Morton RW, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384. PMID:28698222. DOI:10.1136/bjsports-2017-097608. https://pubmed.ncbi.nlm.nih.gov/28698222/
- Thomas 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. J Acad Nutr Diet. 2016;116(3):501-528. PMID:26920240. DOI:10.1016/j.jand.2015.12.006. https://pubmed.ncbi.nlm.nih.gov/26920240/
- Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. PMID:28642676. DOI:10.1186/s12970-017-0177-8. https://pubmed.ncbi.nlm.nih.gov/28642676/
- Messina M, et al. No Difference Between the Effects of Supplementing With Soy Protein Versus Animal Protein on Gains in Muscle Mass and Strength in Response to Resistance Exercise. Int J Sport Nutr Exerc Metab. 2018;28(6):674-685. PMID:29722584. DOI:10.1123/ijsnem.2018-0071. https://pubmed.ncbi.nlm.nih.gov/29722584/
- Hevia-Larraín V, et al. High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations. Sports Med. 2021;51(6):1317-1330. PMID:33599941. DOI:10.1007/s40279-021-01434-9. https://pubmed.ncbi.nlm.nih.gov/33599941/
