The average human sperm cell is around 50 microns long, roughly the diameter of a hair or the thickness of a heavy-duty plastic bag. Under a microscope, amid a galaxy of proteins, sugars, dust and dead cells, they look like broken satellites, spinning crazily without direction. The motion is generated by the sperm cell’s long flagellum, which can propel it the length of its body every second. That’s under ideal conditions, when a man has been exercising and eating clean, abstaining from alcohol and cigarettes, steering clear of saunas and any endocrine-disrupting chemicals and, certainly, avoiding androgenic steroids.
So when Felix van der Heiden and Manu Bos examined their samples during a March visit to the San Francisco offices of the biotech start-up Sperm Racing, they were shocked by what they found. To the naked eye, they looked like robust young men, tall and broad-shouldered, with feline eyes and complexions like a Ken doll’s. Back in the Netherlands, Bos had been a sponsored skateboarder and was now an influencer; van der Heiden, under the handle Zeta, had parlayed his handsome face and washboard abs into a career as a looksmaxxer, with over 700,000 followers on TikTok. There was just one problem.
“ His sperm — like 60 percent is dead,” van der Heiden said. “And for me, everything’s dead. Just rotten inside.”
It wasn’t a total surprise, van der Heiden admitted. He’d been doing testosterone replacement therapy and dabbling in selective androgen and estrogen receptor modulators. His bloodwork had been showing low levels of luteinizing hormone, or LH, which tells the testicles to produce testosterone and, indirectly, sperm. If he wanted to have children, he would have to start injecting a peptide called human chorionic gonadotropin, or hCG, which mimics LH, to get his testes back online. “ It just takes time,” he said.
Van der Heiden persuaded the technician to check another slide, and he obliged. The average young man produces 50 million sperm per milliliter of semen. Each slide held enough fluid to contain a few thousand sperm cells. This one had two twitching in it. Bos was not impressed. “His doesn’t work, and mine is almost as bad,” Bos said.
“No, I got two sperms,” van der Heiden replied.
They’d planned on coming to San Francisco and doing a sperm race, hoping to make — what else — video content for their YouTube channel, Dutch Brahs. And they didn’t have 90 days for their sperm to recover. Bos suggested bringing in ringers, though that would run counter to the Sperm Racing ethos.
Currently valued at $50 million, Sperm Racing is a start-up devoted to, well, racing human sperm through an artificial reproductive system. At their office and across the country, they’ve hosted matches with college students, streamers and influencers — all in the name of raising awareness about male infertility. In the last decade, some studies have found that sperm quality across the developed world has dropped precipitously. On average, young men today produce half as much sperm as men of their grandfathers’ generation. There are many competing explanations for this phenomenon, but one thing scientists can agree on is that sperm quality, and specifically sperm motility — that is, how fast they swim and for how long — is a decent proxy for male health. Healthy men make healthy sperm. Healthy sperm swim faster. And the fastest sperm wins.
“We’re turning health into a competition,” one of Sperm Racing’s founders, an 18-year-old named Eric Zhu, told me.
Van der Heiden’s languid sperm were an extreme example of the problem the company aims to highlight. Any young man’s social media feeds will be awash in contradictory and potentially bad advice on improving health. (Van der Heiden is a part of this industry; in recent weeks, he has made sponsored posts for creatine chews and supplements called D-Bloat and U-Glow.) In a sense, Sperm Racing aims to cut through that noise by reducing male vitality down to its absolute essence. “It turns this very taboo concept to a biomarker that everyone cares about,” Zhu said.
Of course, the company also adds to that noise. Sperm Racing employees spend much of their time turning the sperm races into video content, which ideally steers customers toward the company’s revenue-generating businesses. There’s Andros, a line of plastic-free boxer briefs, and a fertility supplement in the form of a pineapple-flavored gummy called Sperm Worms. Tagline: “Boost Your Boys.”
Sperm Racing seems to represent the final phase of a cultural transformation taking place in the tech industry. In the ’10s, Silicon Valley fostered a rapacious and disruptive business culture that nevertheless spoke in (and seemed to believe in) progressive platitudes. The ’20s have proved quite different: The Valley has embraced an openly masculine and competitive posture — or at least it wants to project that image. And here in one start-up was its most bluntly literal expression.
I met van der Heiden and Bos during the week I spent at Sperm Racing headquarters in San Francisco. My plan had been to follow the founders around as they prepared for a big race to be held at the Chase Center. The potential matchups included two former N.B.A. All-Stars and two much-loathed A.I. titans. But I soon learned that the event wouldn’t be happening. At an all-hands meeting, one of the company’s founders, Shane Fan, made an announcement. From that day on, Sperm Racing would be dedicated to producing a World Cup. Never mind one big race in front of a live audience — they would run dozens of them.
Drawing contestants from 128 countries, the monthlong single-elimination tournament would provide over a hundred matches. Using A.I., the company could translate commentary into any language, expanding its reach even further. Any race could be clipped a half-dozen different ways and circulated around the internet. As soon as possible, they needed to bring in tens of thousands of applicants, send out sample kits, process them and build out their marketing plan. “ So it’s going to be like a sprint for the next whole year,” he said.
At 23, Fan was a bit older than the median Sperm Racing employee; only one person in the office was over 25. And Fan, like many at the company, has a background in social-media content. After graduating from the University of California, Berkeley, at 18, he became an internet personality, eventually racking up over one million followers on TikTok. Around the offices of Sperm Racing, he was what passed for a wise old man.
The problem with live celebrity matches, he explained, was that there was only so much content they could generate. Even though a big-name matchup was sure to go viral, the success wouldn’t last long.
The algorithm rewards a constant flow of content, Fan said, which is exactly what a World Cup would provide. And the matchups could be carefully engineered for maximum virality. “We’re doing Russia vs. Ukraine,” Fan said. “Israel vs. Lebanon.” Tragically, the world may never see these showdowns. Before I could file this article, the company would pivot again.
It was Zhu’s idea to race sperm. The son of Chinese immigrants, he grew up in small-town Indiana, though he talks with the nasal accent and 1.5x speed of the Bay Area. During the pandemic, Zhu got his first computer, and within a few months had taught himself the basics of coding. He started a software-as-a-service business called Aviato. (It was named after a fictional start-up from the TV series “Silicon Valley.”) By the age of 15, he had raised $2.3 million, and managed to get himself expelled from high school for taking too many business calls from the bathroom. Zhu moved to San Francisco and, in his telling, fell in with a circle of longevity enthusiasts who competitively tracked their sperm counts.
In 2024, one of Aviato’s early investors, Joe Lonsdale, persuaded Zhu to enroll at the University of Austin, which was founded in 2021 by Lonsdale and other prominent conservative donors. There, Zhu seems to have spent a few months trolling fellow students by wearing a red Kamala hat and getting two classmates to wrestle after smearing themselves, respectively, in olive oil and canola oil. In a vindication for MAHA, olive oil won.
One weekend during his time there, Zhu says, he was flown to New York with a group of other students for a meeting with a secretive billionaire donor to the school. When the donor asked Zhu to pitch his craziest business idea, he recalled those sperm-obsessed longevity guys from San Francisco. He laid out a vision for a company that would help men track their health by racing sperm. The donor encouraged Zhu to make it a reality.
Zhu reached out to his friend Nick Small, a 16-year-old prodigy of crypto arbitrage, who was well connected in the New York tech scene. Fan joined them, and over the course of an all-nighter at the Paramount Hotel, the three conceived of Sperm Racing and wrote up a manifesto. The tone is somewhere between LinkedIn slop and an underprepared high schooler bluffing his way through a class presentation — the whole thing formatted like a poem.
when people hear about it, they ask me the same thing every time:
wait is this actually happening?
AND THE ANSWER IS ALWAYS
hell yeah, it is.
By late 2024, the three had raised over $1 million from investors led by the hedge fund and venture capital firm Karatage, along with Figment Capital and Karman Ventures. Sperm Racing spent most of this initial investment on its debut event in April 2025. In a rented soundstage in Los Angeles packed with curious fans, two young men faced off, one representing the University of Southern California, the other the University of California, Los Angeles, with a musical interlude by Ty Dolla Sign. The winner (U.S.C.’s representative) received a golden sperm trophy; the loser was doused in white goo. The race livestream glitched out and there were plenty of dull moments, but the buzz it generated proved there was interest in the sport.
One angel investor, who agreed to communicate with me only on the condition of anonymity, had already seen multiple pitches in the male fertility space before he met Sperm Racing’s founders. Those other companies were doing it in a “sterile” direct-to-consumer way, with “generic websites, clinical language,” the investor told me. “Eric’s insight was to flip that entirely: make it competitive, make it social, make it funny. The spectacle would act like a Trojan horse for a male health business.”
Racing sperm does involve some actual science. And for that, the company relied on the expertise of Rishi Kanaparti, who led the company’s biology department and was, improbably, 17. “When I first saw sperm racing on TV, I was kind of skeptical,” Kanaparti said as he showed me the laboratory. Under his white lab coat, he wore a black graphic T-shirt and baggy, raver-style jeans. His wild bleached hair gave him the appearance of a mad scientist who had accidentally electrocuted himself. Before joining Sperm Racing, Kanaparti was dual-enrolled at his Atlanta high school and Georgia State. In his spare time, he researched how fluids travel through the cardiovascular system in a lab at Georgia Tech and published several papers on the subject. When he saw for himself that the science behind sperm racing was legitimately interesting, he left his program in Georgia and moved to San Francisco. He was completing his G.E.D. online while running the lab.
The process borrows from well-studied I.V.F. technology, Kanaparti explained. First, the team purifies the semen samples in a centrifuge. Then they pipette the sperm into two parallel 3,800-micron (3.8-millimeter) microfluidic racetracks etched into silicone chips. These chips are fabricated from molds in an ad hoc clean room set up next to the first-floor bathroom.
The environment within the racetracks is designed to emulate the human reproductive system. In a process known as rheotaxis, the sperm move against a steady flow of warm fluid that mimics cervical mucus. Like salmon swimming upstream, they cling to the walls of the track to avoid the central current and maintain their sense of direction. On Kanaparti’s tracks, however, the sperm encounter unnatural obstacles: tight sections, sharp corners and pillars that separate the best from the rest.
Watching the raw footage from the microscope camera, it’s difficult to tell what’s going on. The sperm and the track are both translucent, with bubbles, particles and dust adding to the visual chaos. To identify the leaders of the pack, a computer vision system applies object detection software to the raw data, the same way a traffic camera picks out speeding cars. This data is then put through 3-D generation software, which transforms it into the slickly produced footage the audience sees onscreen. In the final cut, two or more competitors’ sperm are shown in different colors jostling for position on the same track. The camera follows the action from overhead, with occasional close-ups at crucial moments of suspense. “For this to be entertaining and actually raise awareness, we need to make it cool to watch, like F1,” Kanaparti said.
But making that footage entertaining requires more than cool graphics. To understand how sperm racing reaches its full dramatic potential, I visited the production studio of Gabe Cataldi, the company’s announcer. Tucked in the back of the lower level, past desks littered with hot sauce, coconut water, creatine and baby oil, was Cataldi’s lair. The walls were padded with foam for soundproofing, and two huge lights shone down on a newscasting desk positioned in front of a green screen. A banner attached to the front of the desk read “SMNN,” pronounced “see-men-en.”
Cataldi’s job is harder than it looks. The contestants are sex cells that cannot make adjustments or pit stops. “They’re uncoachable athletes,” Cataldi said. As a commentator, he has to bring both enthusiasm and drama to the action of microscopic cells swimming through a channel. Cataldi told me that he likes to borrow terms from other sports broadcasts: “Metaphors of, like, ‘he’s asking the question,’ ‘he answers it,’ ‘he opens the door, goes through, kicks the door in.’”
But what really excites him are the personal back stories. He imagined a matchup between a macho “Andrew Tate type” and a “vegan skinny” guy who “looks like a twink.” If the musclebound meathead was actually unhealthy, it would be a perfect upset with a positive message: Virility can come in surprising packages. “Society, we should be praising this guy,” he said of his imaginary twink champion. “Biologically, the girls should be seeking him.”
Cataldi has been giving these biological imperatives more thought now that he and his wife, who lives in New Zealand, are thinking about having their first child. But in some ways, Cataldi is already a father. He shares a San Francisco apartment with two other Sperm Racing employees, with another three in the apartment below, and has taken to looking after them. “They call me Unc and Dad,” he said. (He’s 33 years old.) Cataldi wakes at 8 a.m. for his run and knocks on the guys’ doors. And as the only employee above the age of 25, Cataldi had the unofficial job of renting and driving a van for a team-building trip to Six Flags.
Testing racetracks requires employees at Sperm Racing to regularly provide samples, and almost everyone in the office had taken part in internal company scrimmages — except Cataldi. “ I just felt really awkward,” he told me. “ But I’m in the best shape of my life, and I will maybe — I’ll go against you.”
Before I realized what had happened, I’d been challenged to a sperm race. My journalistic curiosity was piqued; for years I’d been thinking about the intersection of masculinity, health and wellness, and here was an opportunity to test all of these at once. But at stake was more than professional duty. My honor as a man, whatever that was, demanded I accept. Just a year apart in age, we would be racing in the Unc Division.
On race day, I handed a plastic cup with a blue lid to a lab tech, who stowed it next to Cataldi’s in the incubator, where they rested for 10 minutes at 98.6 degrees Fahrenheit. Millions of my cells were, hopefully, zipping around in there. As news of the race spread through the office, a crowd formed in front of the wall-size TV.
As the channels opened and the sperm flooded the chamber, Cataldi resumed his role as announcer. He took an early lead with a single sperm, R1, darting ahead. “I’m cooking him,” he said. But soon my L1 and L2 racers were pulling up alongside his. “My guy is completely lost!” he shouted at the screen. As my first sperm crossed the finish line, his was still stuck at the halfway mark. The whole thing lasted just 16 seconds. It was a blowout.
“I got sperm-mogged,” he said.
“That’s unfortunate,” Small said, patting Cataldi on the back.
The workday was coming to an end, and people were drifting back to their desks to wrap things up and prepare for the weekly team dinner. The guys arranged themselves around a long folding table set with chopsticks and 15 containers of microwavable Kraft mac and cheese. Behind them clips of horses played on the TV. The previous week’s team dinner had been a Shabbat; this week was International Women’s Day and a belated Lunar New Year celebration. The horses on the screen were “auspicious,” Zhu said; it was the Year of the Horse.
Before the meal could begin, there was one final contest. Each week, a different member of the team organizes a multiple-choice quiz in Kahoot!, the app beloved by teachers and students across the United States.
“Guys, repeat after me: We are very against cheating at Sperm Racing,” Zhu said. “ If you’re cheating, you will get spankings.” The screen changed to the start page of the Kahoot! quiz. The title was “Gender, Feminism and LGBTQ+ Movements: A Knowledge Challenge.” I had expected something about the N.B.A. or V.C. firms, but in this area I was more confident. I read a lot of feminist and queer theory in college. Many of the company’s employees were barely older than “RuPaul’s Drag Race.” I was ready to run a victory lap.
Question 1: Which concept explains how gender inequality overlaps with race, class and other identities?
That was easy: intersectionality.
Question 2: Who developed the theory of intersectionality?
My first thought was Audre Lorde. But she wasn’t up there. I panicked and chose bell hooks — wrong. It was Kimberlé Crenshaw. As I watched the rankings update, I saw that almost everyone else in the room had gotten it right. From there, things went downhill. I didn’t know the name of the historically lesbian neighborhood in San Francisco (Bernal Heights) or the city’s oldest continuously operating gay bar (Twin Peaks Tavern). When the quiz was over, the screen showed that out of 15 contestants, I came in 12th. The winner, with a perfect score, was van der Heiden — Zeta.
Of the many surreal moments I experienced at the Sperm Racing office that week, this was perhaps the strangest. Given Zhu’s love of trolling, I considered whether it was all an elaborate prank — but the enthusiasm in the room felt genuine. The guys really did want to prove who knew the most about toxic masculinity, just as they wanted to see who had the fastest sperm or the heaviest squat max.
After dinner, I approached van der Heiden. He had skipped trade school to focus on content creation full time, so where had he learned all this stuff?
“Just TikTok,” he said, with a shrug.
In May, Zhu got in touch. Sperm Racing was pivoting again. One-third of the team had been replaced, including Kanaparti, the head of biology. Cataldi might stick around to make content on a contract basis, but his humor wasn’t exactly what the founders wanted for the rebrand. “We don’t want to be degenerate anymore,” Zhu said. The company was “steering away from the cheap jokes.” Now, they were leaning toward the name Biomarker Sports instead.
The name “Sperm Racing” had lasted only six spermatogenesis cycles, but the company would still race sperm, Zhu assured me. It just wasn’t the sole marker of health they wanted to measure and optimize. According to the pitch deck, there would be blood draws, cryo-chamber stress tests and a “VO2 max face off,” with a sperm race as the final leg of the contest. The idea behind the pivot, Zhu explained, was to appeal to an older audience, men ages 25 to 40. This made a certain amount of sense: The Zoomers running the company might have found the edgelord approach amusing, but they were hardly facing down difficult family-planning questions. Men who are struggling with their fertility may want something more serious. Whether these hypothetical customers would be willing to put their reproductive health in the hands of teenagers was another question entirely.
The civilization-level problems the business claimed to want to solve were colliding with business demands and the dull realities of the attention economy. In a funny way, Zhu and the others had backed themselves into the corner of the Valley entrepreneurs who came before — saying they wanted to change the world, and mostly making content instead. At times, these imperatives appeared hopelessly at odds, but Zhu didn’t seem to mind.
When I had my last one-on-one with him back in San Francisco, it was a beautiful afternoon in Yerba Buena Gardens, and the birds and the bees were singing about spring. Maybe his “crazy experiment,” as he called it, wouldn’t last, or maybe one day he’d be looking back and telling epic tales about his life: creating a sport bigger than F1, saving humanity from existential collapse. I asked him whether he planned to have children one day. He described a vision of himself as a patriarch, lying on his deathbed and surrounded by his progeny. “Grandchildren. Grandchildren’s grandchildren.” He wanted to be able to look back on his life with pride, and he felt sperm racing — in whatever form it took — would allow him to do that. “Think about the dad lore,” he said.
Daniel Waite Penny writes about the culture and politics of masculinity, health and the environment. He has a podcast called “Non-Toxic.”
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