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Endurance Athletes Need More Protein
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Runners tend to obsess over carbs—and for good reason. But if you’re not giving enough thought to protein, especially around tough training or low-carb days, you might be missing a key opportunity to boost adaptation, recovery, and long-term performance. A recent review highlights just how critical—and underestimated—protein is for endurance athletes.
The narrative review dug into recent metabolic studies focusing on the protein needs of endurance athletes. Most of the research involved trained runners, cyclists, and triathletes performing prolonged (~90-minute) endurance sessions. The review focused on daily intake requirements, optimal protein timing, and unique needs during carb-restricted training, recovery days, and high-volume periods. In other words—adaptation rather than protein’s direct effects on performance. Here’s what you need to know:
• Daily protein needs are higher than most runners think: Aim for ~1.8 g/kg of body weight/day (that’s 126g/day for a 70kg runner). For those of you who prefer the imperial system, that’s ~0.8g/lb. On days when (or if) you perform carbohydrate-restricted training or maybe a fasted exercise session, go even higher—up to 2.0 g/kg or 0.9 g/lb.
• After hard runs: To maximize recovery, target 0.5 g/kg (0.22 g/lb) of protein in your recovery meal to stimulate muscle repair. Pair this with carbohydrates for the most benefit.
• Adding protein during exercise doesn’t improve endurance performance when carbs are adequate, but it might help during ultra efforts or low-carb sessions to minimize protein breakdown and muscle damage. Remember—protein is not a usable source of energy by the body.
• Women in the luteal phase of their cycle may need even more protein: The authors recommend ~1.9 g/kg/day (0.86g/lb) to counter elevated amino acid oxidation.
What this means for runners
Think of protein not just for strength gains but for endurance resilience. Upping your protein intake can help repair muscle, support mitochondrial function, and maintain performance during heavy training or low-energy availability periods. It’s especially crucial if you’re experimenting with fasted runs, carb periodization, or just feeling beat up after hard efforts. And yes, this applies to everyday runners, not just elites. Carbs fuel the run, but protein helps us recover and adapt.
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RELATED ARTICLE: How Much Protein Do Runners Need? The Ultimate Guide To Protein For Runners
🎙️ Boston, Bannister or Kipchoge: We Debate the Biggest Running Milestones
In this episode, Katelyn, Alex, and Michael debate some of running’s biggest milestones — from elite feats like the sub-2 marathon 🕒 to personal goals like a first BQ 🎯 or breaking 4 in the mile ⚡.
Whether you’re chasing history or your own PR 🏃♀️🏃♂️, these iconic barriers have something to say.
Let’s see who makes the strongest case 🗣️🔥.
Want to Run a Faster Marathon? Fuel Smarter
How much does mid-race nutrition impact your finish time? A new study from the Seville Marathon has some surprising answers.
Researchers surveyed 160 runners (primarily men, average age 42) who completed the 2022 Seville Marathon, examining what they ate and drank before, during, and after the race. They wanted to see if fueling habits—and who gave them advice—had anything to do with performance.
Runners who hit the recommended 60–90g of carbs per hour during the race were significantly more likely to finish the race in under 3 hours, but most runners felt short of this—the average intake was just 35g/h, well below guidelines. Hydration was also inadequate for most of the runners. Fluid intake averaged 466mL/hour. Paradoxically, runners who drank less relative to their body weight were more likely to finish in under 3 hours.
Average sodium (salt) intake was 192mg/hour compared to the recommended 300–600mg/hour, and caffeine intake was a modest 57mg/hour (there are no recommendations for caffeine intake during marathon running).
What about post-race recovery? Most of the runners (not surprisingly) hit the carbohydrate recovery target of 0.8g/kg but fell way short on protein, consuming just 0.1g/kg compared to the 0.3g/kg recommended for endurance athletes.
Finally, very few runners got professional advice—only 19% consulted a sports dietitian—but those who had a nutrition plan were more likely to run fast.
What this means for runners
If you’re serious about your marathon time, fueling during the race may be just as important as your training miles. This study adds to growing evidence that hitting mid-race carb targets (60–90g/hour) improves performance. Most runners are underfueled and underhydrated, and few are getting expert guidance.
Also worth noting: drinking too much may slow you down, not help. Overhydration could lead to bloating, GI issues, or dilutional hyponatremia. Find the right balance and adjust based on race-day conditions.
RELATED ARTICLE: How To Fuel For A Marathon: What To Eat Before, During, + After Your Race
Running a Marathon Causes a (Literal) Change of Heart
Endurance exercise is good for the cardiovascular system; there’s no denying it. But running long and hard takes a toll on the body and can result in short-term (though reversible) changes to the heart, a response that might differ depending on one’s biological sex.
A new study explored whether running a marathon affects men’s and women’s hearts differently. It examined 61 amateur marathoners (34 men, 27 women)using 3D heart imaging and blood tests before, immediately after, and two weeks after a marathon. Researchers explored how the heart adapts (or struggles) with endurance stress.
After the race, all runners, especially men, had larger right ventricles with an increased right ventricular volume. Left ventricle volume decreased post-race, but ejection fraction (a measure of the heart’s pumping capacity) mostly stayed the same, except for men, who saw a drop.
Female runners not only had better baseline cardiac function, but their hearts bounced back faster after the marathon, suggesting superior recovery in this group.
All runners showed increases in cardiac stress and injury markers after the race—Galectin-3 (an inflammatory protein linked to fibrosis) rose the most in less-trained runners and correlated with bigger drops in left ventricle function.
Men had higher creatine kinase (a marker indicating muscle breakdown) and endothelin-1 (a protein linked to heart strain) levels.
Women had more pronounced increases in inflammatory markers, including one called interleukin 6 (IL-6 for short). However, most of these markers returned to normal within 2 weeks of finishing.
What this means for runners
If this sounds scary, don’t be alarmed. All this means is that marathons temporarily stress the heart—most of these changes are normal post-race phenomena, but it means that we should be mindful of recovering slowly after a marathon.
It turns out that women may be slightly more protected, possibly thanks to estrogen’s anti-inflammatory and heart-buffering effects. Less-fit runners also get hit harder—a reminder to build training gradually and only push yourself in long events when you’re ready.
RELATED ARTICLE: Why Is My Heart Rate So High When I Run? 11 Possibilities Behind An Elevated HR
SHORT STUFF You Don’t Want To Miss
HERE’S WHAT ELSE YOU WOULD HAVE RECEIVED this week if you were a subscriber to the complete, full-text edition of “Run Long, Run Healthy.”
- Does running a marathon shrink your brain?
- How shoe stack height affects running stability and biomechanics.
- A supplement that might increase fat burning during exercise.
Thanks for reading. As always—Run Long, Run Healthy
~Brady~
