Not too long ago, protein wasn’t on the radar of endurance athletes. Instead, most had a one-track mind: carbs, carbs, and more carbs. Spaghetti dinners before marathons, energy gels mid-race, and recovery drinks packed with sugars were the holy grail.
Protein? That was for bodybuilders and strength athletes. For endurance athletes, it was a background player—at best.
But times have changed. Many studies published over the past decades have shown that protein matters for endurance athletes, too. A new review gathers all the scientific tidbits and serves them up into redefined recommendations on how much protein endurance athletes really need.1
Here’s the juicy stuff:
Why Protein Deserves a Spot on Your Running Playlist
Here’s what protein does for endurance athletes.
Protein isn’t just the builder of biceps. For an endurance athlete, it wears multiple hats:
- Stimulates muscle protein synthesis during recovery.
- Repairs and remodels your hardworking muscle fibers, plus your mitochondria (the tiny energy factories inside your cells).
- Replenishes amino acids burned as fuel during long sessions.
- Supports immune function, mitigates fatigue during high-intensity training periods, and reduces muscle soreness.
- Helps maintain your lean muscle mass, especially during periods of low energy availability or intense training. Your heart is not the only muscle critical to endurance performance.
So yes, protein has moved out of the weight room and onto the trails.
What the Study Found
- The baseline daily needs for endurance athletes is around 1.8 grams of protein per kilogram (approximately 0.82 grams per pound) of body mass per day. That’s way above the old 0.8 g/kg general recommendation.
- During carb-restricted training or rest days, it’s a good idea to bump your protein intake to over 2.0 g/kg/day (0.91 grams per pound). Yes, you likely need more protein when you’re not training. That’s when your muscles need it the most for recovery.
- Aim for about 0.5 g/kg of high-quality protein per meal to stimulate muscle protein synthesis (MPS)—that’s ~35g for a 70kg (154 pound) athlete.
- Protein during exercise? Not necessary for performance—unless you’re deep into ultra-endurance territory. It might upset your stomach, but there is no evidence you need for “normal” endurance training.
- Women might need slightly more protein than usual, especially during the luteal phase of their cycle.
In addition, protein seems to stimulate contractile (movement-related) muscle protein synthesis more than mitochondrial (endurance-related) proteins in the short term. So your recovery shake might be doing more for your strength and muscle maintenance than your stamina—but both matter in the long run.
What This Means for You: Practical Recommendations
So you’re lacing up your shoes, ready to pound pavement. Here’s what you do with this info:
- Don’t skip the protein post-run (or post-bike, -swim, or -whatever). After your long runs or rides, don’t just inhale carbs. A protein shake, eggs, Greek yogurt—whatever works for you—aim for that ~0.5 g/kg dose within an hour.
- Match your protein intake to your training intensity. Easy day? Keep it around 1.8 g/kg. If you’re doing big back-to-back sessions, training fasted, or if you’re on a low-carb diet? Push it over 2.0. And rest days—that’s when your body needs it the most.
- During really high training loads, like a marathon prep, make sure your protein intake is on point. It might help you stay healthier, reduce soreness, and keep your immune system in check.
- Ladies take note. In the luteal phase of your cycle (the back half, after ovulation), your protein needs may be a bit higher. Don’t shy away from adjusting your intake accordingly.
Final Rep
This isn’t about ditching carbs—far from it. They’re still the king for performance and the fuel that keeps the engine going. But protein is the repair crew that keeps that engine in tip-top shape, and you need both for peak performance.
More about protein from us:
>> Protein for Strength Training: The Ultimate Guide
>> The 30 Best Protein Foods for Muscle Growth
>> Protein Requirements by Age: A Complete Guide
>> How Much Protein To Build Muscle After 60
And, if you’re need help figuring out how much protein you need, check out our nifty protein calculator!
