You finish a hard run, ride, or swim. You reach for a protein snack—maybe a bar or a shake with 15-20 grams. Job done, right?
Not so fast. Recent studies are showing that endurance athletes have higher protein needs post-exercise than we used to think—and that leucine is the key to unlocking recovery.
Let’s break it down.
The Training-Adaptation Connection
After endurance training, your body goes into overdrive to adapt:
- Repair damaged muscle fibers
- Rebuild mitochondria
- Remodel muscle proteins
This remodeling process is driven by muscle protein synthesis (MPS), which depends on high-quality protein—especially the amino acid, leucine, known for its role in triggering MPS.
How Much Protein (and Leucine) Do You Need Post-exercise?
In a study of endurance athletes, participants exercised for 90 minutes and were then given either 0g, 15g, 30g, or 45g of protein containing increasing amounts of leucine (from 0g to 4.3g).
Adapted from: Churchward-Venne TA, Pinckaers PJM, Smeets JSJ, et al. Dose-response effects of dietary protein on muscle protein synthesis during recovery from endurance exercise in young men: a double-blind randomized trial. Am J Clin Nutr. 2020;112(2):303–317.
MPS was maximized at 30g of protein containing ~3g leucine. More than that didn't provide additional benefit, and less didn’t deliver the full muscle recovery stimulus¹.
Meanwhile a new review article found that, on average, 5–10g of protein is oxidized per hour of endurance exercise, used directly for energy². So if you’re training for 90 minutes, you may have lost up to 15g of usable protein during the session itself. That loss must be replaced so your body can start the repair process.
The Leucine Boost Effect
What if you don’t want to consume a full 30g of protein in one go?
Good news: a study comparing 20g of plant protein boosted to 3g leucine to 20g of whey protein also enriched to 3g leucine - found identical MPS responses. When subjects consumed the plant protein without the extra leucine their MPS response was significantly lower. In other words, it's the leucine that matters most in triggering recovery³.
That’s why we designed ADDRA bars with:
- 20g of high-quality plant protein
- Boosted to 3g leucine
You get the full MPS response of 30g of protein—or a whey shake—in a compact, efficient and easy-to-eat on-the-go recovery snack.
For Endurance Athletes, It Matters More
Combine higher daily needs with the protein you burn while training, and it's easy to see how even disciplined athletes can fall short without thoughtful recovery.
Bottom Line
- After endurance training, your protein needs are higher than you think.
- Aim for ~3g leucine post-exercise, whether from foods containing 30g total protein or from leucine-enhanced 20g foods or snacks.
- Not all bars are created equal—look for products that actually hit that leucine threshold.
📝 Coming Next in the Series…
You’ve seen that hitting ~3g of leucine post-exercise can unlock recovery and adaptation.
But what if your protein looks complete on paper—but still doesn’t trigger the rebuild?
Next up: Why leucine is the amino acid that flips the recovery switch—and how most proteins fall short without it.
We’ll break down:
- What leucine actually does inside your cells (and why it matters)
- Why most plant proteins don’t hit the 3g threshold needed to trigger MPS
- The newest research comparing whey vs. leucine-fortified plant protein
- And how to spot the bars, shakes, and meals that actually work
⚡ Without leucine, you're fueling—but not adapting. This one amino acid changes everything.
👇
References
- Churchward-Venne TA, Pinckaers PJM, Smeets JSJ, et al. Dose-response effects of dietary protein on muscle protein synthesis during recovery from endurance exercise in young men: a double-blind randomized trial. Am J Clin Nutr. 2020;112(2):303-317.
- Clauss M, Jensen J. Effect of Exercise Intensity, Duration, and Volume on Protein Oxidation During Endurance Exercise in Humans: A Systematic Review With Meta-Analysis. Scand J Med Sci Sports. 2025 Apr;35(4):e70038.
- Lim C, Janssen TA, Currier BS, et al. Muscle Protein Synthesis in Response to Plant-Based Protein Isolates With and Without Added Leucine Versus Whey Protein in Young Men and Women. Curr Dev Nutr. 2024;10;8(6):103769.
