Muscular runners crushing ultramarathons have taken over fitness feeds everywhere.
They’re called “hybrid athletes,” and they’re sparking fierce debate about what’s actually possible naturally.
In a recent GQ article, writer Hannah Singleton explores whether these impressively built endurance athletes are legitimate—or if there’s something else powering their physiques.
The answer might surprise you.
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The New Fitness Ideal
Nick Walker embodies everything “hybrid athlete” has come to mean. As a former NCAA Division I baseball player, he spent four years deliberately gaining weight to build muscle mass.
Now he maintains a bodybuilder physique—chiseled six-pack, capped shoulders, developed chest—while training for one of America’s toughest ultramarathons.
I haven’t lost anything, and I’ve been training since January. I’m still 235 pounds.
Walker’s preparation for the Leadville 100 involves both heavy lifting and long-distance running, often on the same day.
Traditional fitness wisdom suggested you had to choose: bodybuilder physique or endurance athlete stamina. Bodybuilding coaches warned that cardio would kill gains. Runners feared extra muscle would slow them down.
Hybrid athletes now serve as walking contradictions to both beliefs.
Social Media’s Fitness Phenomenon
Google searches for “hybrid athlete” tripled between December 2025 and April 2026. Derek Morgen, who founded VTLZR community for hybrid athletes, noticed explosive growth three years ago.
I nerded out about it three years ago tracking the hybrid athlete subreddit.
Competitions like Hyrox fuel interest—these events combine running with conditioning movements like sled pushes and wall balls, demanding both strength and endurance simultaneously.
But hybrid training isn’t actually new. Physical Activity Guidelines for Americans have recommended combining resistance training with aerobic exercise for decades. Football players and mixed martial artists always trained for both qualities.
Alex Viada coined “hybrid athlete” in his 2015 book, defining it simply as anyone training for two competing goals.
The Skepticism Problem
Today’s hybrid athlete represents something far more specific: someone who lifts heavy, runs far, and maintains remarkable muscle mass throughout.
Given widespread experimentation with performance-enhancing peptides, steroids, and rampant AI imagery, hybrid athletes face constant scrutiny. Walker’s YouTube content attracts comments questioning whether his physique comes “out of a syringe.”
Some fitness influencers create entire videos suggesting testosterone replacement therapy, peptides, or performance-enhancing drugs must explain these physiques. Others insist disciplined training, meticulous nutrition, and elite genetics deserve credit.
What Science Actually Says
Doubt surrounding hybrid athletes has scientific foundation. Exercise scientists study the “interference effect”—how endurance and strength training compete for bodily resources.
Brad Schoenfeld, leading muscle hypertrophy researcher and Lehman College professor, explains that modest cardio doesn’t significantly impact muscle growth.
If you’re running marathons, there’s going to be competition for energy reserves. It’s going to be difficult to gain muscle, and you might even blunt muscle growth.
Research supports this concern. A 2022 Sports Medicine study found running affected muscle growth more negatively than cycling or other endurance sports.
The Resource Competition
Building muscle requires lifting near failure, sufficient calories, and adequate recovery. High-volume endurance training demands tremendous resources too—and studies show at least 50 percent of endurance athletes don’t eat enough during training.
From a running performance perspective, excessive muscle creates disadvantages.
If you look at the people who win marathons, they don’t look like bodybuilders. The body adapts for a reason. It’s not good to have a lot of muscle in that case, because you’re carrying around more weight.
Building muscle and endurance simultaneously isn’t impossible—beginners often improve both. But as athletes advance and endurance goals intensify, maximizing muscle growth becomes significantly harder, says Schoenfeld.
Many simply aim to maintain existing muscle, which requires far less training volume than building new tissue.
The Hidden Background Story
One major misconception: hybrid athletes built their physiques through hybrid-style training alone.
Many prominent hybrid athletes, including Nick Bare (founder of Bare Performance Nutrition), come from bodybuilding backgrounds. They spent years exclusively building muscle before adding long-distance running. Bare competed in bodybuilding competitions as recently as 2023.
While Bare discusses his bodybuilding history on his website, that detail gets buried on Instagram and YouTube channels where he’s built massive audiences. Followers see his current physique as hybrid methodology’s product, not years of specialized muscle-building.
Lifestyle Advantages
Walker notes people overlook how lifestyle enables social media physiques. These athletes typically have time for everything required at elite levels:
- High training volumes for both strength and endurance
- Sufficient nutrition to support demanding schedules
- Proper recovery including sleep and mobility work
- Flexible schedules or fitness-related careers
- No competing demands like raising children
Genetics: The Wildcard
Genetics influence outcomes by 50 percent or more, according to Schoenfeld. Specific genes determine baseline muscle mass, growth potential, fat storage patterns, and muscle shape.
Muscle insertions and “muscle bellies”—the length and shape of muscle tissue—determine whether muscles appear long and full versus shorter and peaked.
That’s the wild card. Just because someone takes off their shirt and claims that their training is responsible for everything doesn’t mean that if you do what they do, you’ll get the same gains.
The Influencer Question
Bare and his “Hybrid Boys” crew remain primary targets for Reddit speculation and YouTube analysis. Critics highlight inherent conflicts of interest: professional fitness influencers’ aspirational bodies typically launch product sales.
Viada notes that given steroid prevalence in fitness modeling and bodybuilding, some athletes in this space potentially use—or previously used—testosterone replacement therapy or performance-enhancing drugs.
He offers a hypothetical scenario: Someone weighing 230 pounds, stage-ready from bodybuilding competitions, transitions to testosterone replacement therapy while tapering off anabolic steroids.
They could do the worst running program in the world. High volume, no thought to recovery. And they could lift pink dumbbells once a week and still have a great physique.
Past Use Complicates Things
Even previous enhancement use complicates assessment. Athletes might be completely natural now but carry unusually high muscle mass from prior cycles—levels most people couldn’t achieve without drugs.
It gives you this incredibly high starting point. You got to take an elevator up to the third floor, and everybody else is starting on the first floor, trying to get to the second floor.
Bare repeatedly insists he’s natural, including during a My First Million podcast appearance. Dan Churchill, another group-associated figure, even showed bloodwork on YouTube while promoting natural testosterone-boosting methods.
Walker dismisses accusations entirely, crediting hard work alone.
People are entitled to whatever they want to think. I know for me, I have been doing this stuff for many years now and it’s just a compound effect.
Hybrid athletes represent fitness culture’s latest aspirational identity—but whether their results come purely from training, genetics, previous muscle-building phases, or enhancement remains hotly contested.
