How Much Protein Do Endurance Athletes Need?

How Much Protein Do Endurance Athletes Need?

Spoiler: It's more than you think.

For years, protein was seen as the domain of bodybuilders and gym rats. Endurance athletes? We stuck to pasta, bananas, and a bottle of sports drink. But science (and smarter training) has changed that. We now know protein plays a vital role in not only recovery, but in long-term performance gains for runners, cyclists, triathletes, and any athlete logging serious time on the road, trail, or trainer.

So, how much protein do endurance athletes actually need? And when should you be taking it? Let’s dig into what the latest research says and how you can apply it.

Daily Protein Needs: More Than the Bare Minimum

The FDA recommends 0.36 grams per pound (or 0.8 grams of protein per kilogram) of body weight per day for the general population¹. That’s just enough to avoid deficiency — not nearly enough to support the demands of endurance training.

Recent studies, using the more advanced "indicator amino acid oxidation” method, suggest that even sedentary individuals should be getting at least 0.55 g/lb (1.2 g/kg), and endurance athletes need closer to 0.75–0.82 g/lb (1.6–1.8 g/kg) per day to fully support recovery, adaptation, and performance²³. On rest or recovery days, protein needs may increase to 0.91 g/lb (2.0 g/kg).

That means a 150 lb athlete should aim for:

• 113–123g of protein per day on training days

Up to 136g of protein on rest or recovery days

Why Endurance Athletes Need More

Endurance training creates muscle damage, immune stress, and a demand for mitochondrial growth — all of which require protein for repair and adaptation⁴.

Additionally:

• During long sessions, amino acids are used for energy, especially when carb availability is low. In some cases, 5–10% of exercise energy may come from protein⁵.
• Recovery days may actually require more protein than training days as the body ramps up repair and remodeling processes².
  
  

This is why consistent, adequate protein intake — even on rest days — is essential for building durability, reducing injury risk, and making gains from all the work you're putting in.

Strategic Protein Timing: Recovery and Beyond

Spreading protein intake throughout the day is important, making sure you’re aiming for at least 20-30 grams of protein at each meal. But that’s not going to cut it for athletes. You don’t need to slam a protein shake the second your run ends, but post-workout protein still matters, and timing it around and during your workouts can have additional benefits.

• PRE-WORKOUT: For morning workouts or carb-depleted, "train-low" sessions (used to build fat-burning efficiency), adding 10–20g of protein pre- or during training can help reduce muscle breakdown and maintain performance⁸. We love JAVI for this, it's got the perfect mix of easy to digest carbs and protein for pre-workout fueling.
  
  
• DURING WORKOUT: For efforts lasting 3+ hours, a small amount of protein (typically 1–4g per hour) can help take the edge off hunger, support muscle preservation, and make all-liquid fueling more satisfying. GO FAR and Custom endurance formulas are designed with a few grams of protein per serving for this reason.
  
  
• POST-WORKOUT: 0.5 g/kg of protein post-workout (about 34 grams for a 150 lb athlete) to jumpstart muscle repair and reduce soreness⁶. Try REPAIR or a Custom Protein blend mixed with milk to get you there.
  
  

BEFORE BED: Evening sessions? Don’t skip the post-workout fuel. If you’re headed to bed after an evening workout or a day of heavy training, a casein-rich or slow-digesting protein can support overnight recovery⁷. NOCTURNE mixed with milk is the perfect for packing in some protein before bed, and the added Tryptophan helps you get deeper, more restorative sleep.

Do You Need Protein During Training?

The short answer for most standard training sessions under 3 hours is no, as long as you’re getting enough carbs. Research shows that adding protein to a sports drink during exercise doesn't improve performance or recovery unless carbohydrate intake is insufficient⁹.

However, protein during training has one unique benefit…

One of the challenges of an all-liquid fueling strategy, especially during longer efforts (3+ hours), is hunger. When you're running on carbs alone, your gut can feel empty even if you're meeting your energy needs.

That’s why we build many of our endurance formulas with a small amount of protein — to curb hunger and support muscle preservation — while also giving you a complete, streamlined solution that lets you focus on your performance instead of playing lab tech on the bike.

Research has also shown some additional benefits with consuming some protein during ultra-endurance activity (4+ hours) by sparing muscle tissue and help maintain mental focus¹⁰. 

INFINIT recommends adding 1–4 grams of protein per serving to your endurance formula during long sessions. This small amount helps take the edge off hunger, improves satiety, and keeps you focused and fueled without slowing gastric emptying or causing gut distress.

It’s a simple but effective strategy that we use in our GO FAR formulas and recommend for any athlete relying on liquid nutrition in training or racing.

Bottom Line: Aim Higher Than You Think

If you’re training consistently, chasing PRs, or pushing for peak performance, around 0.8 grams per pound (1.8 g/kg) of protein per day is a smart target. Bump that up to 0.9 grams per pound (2.0 g/kg) on rest days or during recovery weeks.

And while we’re big fans of whole foods — after all, we’ve got registered dietitians who call the shots here — the reality is that consistently hitting 100+ grams of protein per day through food alone can be a serious challenge, especially for busy athletes. That’s where a properly formulated, high-quality protein powder or recovery drink can make a huge difference in helping you meet your daily needs without the guesswork.

And when it comes to pre-, intra-, and post-workout fueling, a dialed-in liquid nutrition strategy (with a little protein) offers major advantages. It’s easier on the gut, eliminates the need to juggle multiple products mid-session, and allows you to hydrate and fuel at the same time — no gels, chews, bars, salt tabs, or spreadsheets required.

Want help dialing it in? Our in-house Formulation Team (yes, actual sports RDs) can help you build a Custom Protein or Endurance Blend tailored to your goals, your training, and your taste buds. Schedule a free consultation to get started.

Additional Resources

1. U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary Guidelines for Americans, 2020–2025. 9th Edition.
2. Witard, O.C., et al. (2024). Protein Requirements of Endurance Athletes: Insights from the Indicator Amino Acid Oxidation Method. Sports Medicine, 54(1), 1–16.
3. Moore, D.R., et al. (2015). Protein intake and muscle function in active individuals. British Journal of Nutrition, 113(4), 581–587.
4. Phillips, S.M., & Van Loon, L.J. (2011). Dietary protein for athletes: from requirements to metabolic advantage. Applied Physiology, Nutrition, and Metabolism, 36(5), 647–654.
5. Lemon, P.W.R. (1998). Effects of exercise on dietary protein requirements. International Journal of Sport Nutrition, 8(4), 426–447.
6. Jäger, R., et al. (2017). International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14(20).
7. Res, P.T., et al. (2012). Casein protein ingestion prior to sleep increases muscle mass and strength gains during prolonged resistance-type exercise training in healthy young men. Medicine & Science in Sports & Exercise, 44(8), 1560–1569.
8. Areta, J.L., et al. (2014). Skeletal muscle protein synthesis in response to isolated protein ingestion following resistance exercise: a systematic review and meta-analysis. Sports Medicine, 44(5), 655–670.
9. Koopman, R., et al. (2004). Combined ingestion of protein and carbohydrate improves protein balance during ultra-endurance exercise. American Journal of Physiology-Endocrinology and Metabolism, 287(4), E712–E720.
10. Saunders, M.J., et al. (2007). Effects of carbohydrate-protein beverage on cycling endurance and muscle damage. Medicine & Science in Sports & Exercise, 39(7), 1236–1248.