Are ‘Hybrid Athletes’ Too Good to Be True?

Nick Walker started functional bodybuilding in earnest during the pandemic. As a former NCAA D1 baseball player, he had to eat constantly to put weight on his smaller frame. But after spending four years “hammering,” trying to build muscle, he has developed the superhero-esque build you might associate with a true gym rat: developed pecs, a chiseled six-pack, capped shoulders, defined biceps, meaty legs. Oh, and he’s into long-distance running too. As he prepares for the Leadville 100, one of the toughest ultramarathons in the country, he’s maintained his weight by following a regimented exercise schedule in which he lifts heavy and runs long–often in the same day. “I haven't lost anything, and I've been training since January,” he says. “I'm still 235 pounds.”It’s a long held belief among the fitness world that you have to pick between the physique of a bodybuilder or the stamina of an endurance athlete. For decades, bodybuilding coaches preached that any amount of cardio would stunt muscle growth. And runners were superstitious about building too much muscle, lest it slow them down. But recently, so-called hybrid athletes like Walker have become living, extremely online proof that you can have giant quads and run them too.As more fitness influencers strive toward ultra-self-optimization and camera-friendly physiques, “hybrid athletes” have emerged as some of the fitness world’s most aspirational identities across Instagram, TikTok, and YouTube. According to Google Trends, searches for “hybrid athlete” tripled between December 2025 and April 2026. “I nerded out about it three years ago tracking the hybrid athlete subreddit,” says Derek Morgen, a fitness coach who started his business, VTLZR, a community for hybrid athletes, after he noticed the “hockey-stick curve” growth of the term. He says it continues to expand, especially as fast-growing fitness competitions like Hyrox, which pairs running with conditioning movements like sled pushes and wall balls, and demand both strength and endurance.In many ways, hybrid athletes are a search-friendly repackaging of an old idea. The Physical Activity Guidelines for Americans have long encouraged people to combine resistance training and aerobic exercise for overall health, and athletes in sports like football and mixed martial arts have always trained for both strength and endurance. Alex Viada, the coach who coined the term in 2015 in his book The Ultimate Hybrid Athlete, defines the label as anyone training for two competing goals.But the 2026 version of the hybrid athlete has come to mean something much more specific on social media: someone who lifts heavy, runs far, and maintains a physique that looks remarkably muscular in the process. At a moment when experimentation with performance-enhancing peptides and steroids is widespread, AI images are rampant, and “natty or not?” has become a regular question among fitness influencers, hybrid athletes are also a lightning rod for online skepticism. Walker’s YouTube short about how to maintain muscle while running is filled with comments like “Everything special about him comes out of a syringe” and “At this point, why not just come clean?” Some fitness influencers have created videos about how testosterone replacement therapy (TRT), peptides, or performance-enhancing drugs (PEDs) must be responsible for hybrid physiques like Walker’s. Others argue that it’s simply the product of years of disciplined training, meticulous nutrition, and elite genetics.The Science Behind Concurrent TrainingFor what it’s worth, the doubt surrounding hybrid athletes is grounded in research: Exercise scientists have long studied what's known as the “interference effect”—the idea that endurance and strength training compete for the body's resources.At modest levels, cardio doesn't appear to have much impact on muscle growth, says Brad Schoenfeld, one of the leading researchers in muscle hypertrophy and a professor of exercise science at Lehman College. But as endurance training volume climbs, the tradeoffs become more apparent.“If you're running marathons, there's going to be competition for energy reserves,” says Schoenfeld. “It's going to be difficult to gain muscle, and you might even blunt muscle growth.” A 2022 study in Sports Medicine even found that running affected muscle growth more negatively than other endurance sports, such as cycling.Building muscle requires lifting weights close to failure, as well as sufficient calories and recovery. High-volume endurance training requires a lot of your body’s resources too, and, according to some studies, at least 50 percent of endurance athletes don’t eat enough during training. It's hard to build muscle when there’s not enough fuel for them.From a running performance perspective, carrying a large amount of muscle can also be a disadvantage. “If you look at the people who win marathons, they don’t look like bodybuilders,” says Schoenfeld. “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.”That doesn't mean building muscle and endurance simultaneously is impossible. Beginners can often improve both at the same time. But the more advanced an athlete becomes—and the more serious their endurance goals get—the harder it is to continue maximizing muscle growth, says Schoenfeld. At that point, many just try to maintain what they have or try not to lose too much. And if you’re just aiming to maintain the muscle you have, it usually requires far less training volume at the gym.The Hard Body ProblemOne of the biggest misconceptions about hybrid athletes, Schoenfeld says, is that they built their bodies from hybrid-style training alone. Many of the prominent hybrid athletes, including Nick Bare, a popularizer of the term and founder of supplement company Bare Performance Nutrition, come from a bodybuilding background—spending years and years building muscle before taking up long-distance running. (Bare competed in bodybuilding competitions as recently as 2023.) Though Bare is forthcoming about his bodybuilding days on his website, that part of his story is less prominent on the Instagram and YouTube channels where he has built his largest audience. Many followers end up seeing his current physique as the product of a hybrid methodology, rather than the result of years of specific muscle-building.Walker also notes that people often forget how much lifestyle enables what you see online. These social media athletes usually have the time to do everything required at a high level—training high volumes, eating enough to support it, recovering properly, and incorporating mobility work. Many work in fitness-related roles, have flexible schedules, or don’t have children competing for time and energy.Genetics also play a massive role—50%, if not more, says Schoenfeld. Certain genes influence how much muscle mass someone starts with, how much they can build, where they store fat, and the shape and appearance of the muscles themselves. A person’s muscle insertions and “muscle bellies”—the length and shape of the muscle itself—determine whether a muscle appears long and full or shorter and more peaked.“That’s the wild card,” Schoenfeld adds. “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.”Nevertheless, Bare and his close crew of athletes, whom he has dubbed the “Hybrid Boys,” remain the primary targets for much speculation on Reddit threads and from YouTube creators. Some internet critics highlight the conflict of interest inherent in most professional fitness influencers: Their aspirational body is usually a starting point for selling you something. Others like Viada say that given how common steroid use has been in fitness modeling and bodybuilding, it wouldn’t be surprising if some athletes in the space are currently using—or have previously used—TRT or performance-enhancing drugs. He gives a hypothetical: Take someone 230 pounds, stage-ready, right out of bodybuilding comps. They transition to TRT as they taper off anabolic steroid use (since stopping abruptly can shut down natural testosterone production). “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,” says Viada.Even past use, he adds, can complicate the picture. Some athletes may be fully natural now but still carry an unusually high amount of muscle from prior cycles—something most people couldn’t build without drugs. “It gives you this incredibly high starting point,” says Viada. “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 has repeatedly insisted he is natural, including in a past appearance on the My First Million podcast. Dan Churchill, another figure associated with the group, even took to his Youtube channel to debunk these claims, showing his bloodwork and promoting ways to boost testosterone naturally.Walker just brushes off the accusations at this point, insisting that his hard work is all it takes. “People are entitled to whatever they want to think,” he says. “I know for me, I have been doing this stuff for many years now and it's just a compound effect.”