Fitness
How Dad’s Fitness May Be Packaged and Passed Down in Sperm RNA | Quanta Magazine
In March 2025, in a preprint uploaded to biorxiv.org, Mansuy and colleagues reported that EVs in mice can transport certain RNAs, metabolites and lipids linked to early-life stress from circulating blood to sperm, with consequences for offspring. The offspring produced by these sperm cells had stress-related metabolic dysfunction as adults and bore the stress signatures in their own sperm RNA. “These changes imply a mechanistic link between sperm RNA modifications and phenotypic features in the offspring,” Mansuy’s team concluded in their paper, which has not yet been peer-reviewed.
Phenotypic Translation
Perhaps the trickiest step to understand is how sperm-borne molecules could influence an adult’s observable traits. In one form of experiment, researchers extract all the sperm RNA from mice that have been raised under stressful or health-altering conditions. Those isolated RNAs are then injected into a zygote. Pups that emerge usually “get the dad’s phenotypes,” Conine said, suggesting that the RNAs alone confer traits from dad to offspring.
But how? During early development, epigenetic processes reign. As one fertilized cell divides into two, and those cells divide again, and so on, one set of DNA instructions is dynamically and repeatedly reprogrammed. The growing body specializes into different cell types and is sculpted into a sequence of increasingly complex forms. It’s possible, then, that early epigenetic alterations to the genome could have significant downstream effects on an adult.
Research out of Conine’s lab, published in 2024, showed that sperm microRNAs alter gene expression in mouse embryos. Experiments like these, he said, support the idea that offspring can inherit paternal traits via the transfer of non-DNA molecular stowaways in sperm.
The recent Cell Metabolism paper took this idea a step further by tracing a mechanism by which this can happen. A team of more than two dozen Chinese researchers focused on the epigenetic transmission of exercise benefits, homing in on a set of microRNAs that reprogram gene expression in the early embryo. These changes ultimately result in skeletal muscle adaptations in adult offspring that enhance exercise endurance. The researchers found that well-exercised mice had more of these microRNAs in their sperm than sedentary mice did. When these microRNAs were transferred into zygotes, the adults they grew into were more physically fit, with more mitochondria in skeletal muscle and higher endurance.
But how did the molecules generate the exercise-positive phenotype? In experiments, the researchers found that the microRNAs suppressed a particular protein, which had the effect of boosting genes related to mitochondrial activity and metabolism.
Intriguingly, the sperm of physically trained male humans also hosted higher levels of many of the same microRNAs than those of untrained cohorts. “This cross-species conservation suggests a potential role for these sperm mi[cro]RNAs in intergenerational exercise adaptations in humans,” the researchers wrote.
The First Draft
The notion that a father’s lived experience can become recorded by his body, transmitted to his gametes and relayed to his offspring is no longer as outlandish as it once seemed. Many researchers in the field are willing to float speculative visions of what could be going on, even as they acknowledge that gaps remain.
“Our hypothesis is that the epididymis ‘sees’ the world and alters the small RNAs it produces in response,” Rando said. “These RNAs are then delivered to the zygote upon fertilization and control early gene regulation and development to shape offspring health and disease.”
Conine speculates that once certain RNAs make their way into the egg, they trigger “a cascade of changes in developmental gene expression that then leads to these phenotypes” of the father showing up in the next generation. Remarkably, this unfolds even though the sheer volume of the sperm’s contents is so much less than an egg’s contents, including the relative amounts of RNA.
The full picture of how paternal experience and behavior might epigenetically influence offspring is not nearly in hand. Researchers are currently piecing the story together, one experiment at a time, rather than proving out every step sequentially in the same set of organisms. One of the gaps is in the characterization of what RNA and perhaps other epigenetic factors do in the zygote to modify genomic activity as it unfolds during development, Mansuy said.
“We are still blind men describing for the first time different parts of the same elephant,” Chen said. “The underlying mechanism is almost certainly an orchestra of a sperm RNA code and factors beyond that.”
Confirming the findings in humans would take enormous effort, but it would be key to turning these findings in mice into “informed medical advice,” Chen said. This would require well-controlled experiments following multiple generations, tracking diet, exercise, aging and environmental exposures, while also using advanced tools to decode sperm-packaged molecules — and then looking for strong correlations between the molecular and phenotypic data.
Even amid the uncertainties, researchers are cautiously moving forward as they learn to believe the results of their own experiments. If they’re right, they will have discovered a new fact of life, Rando said. When he thinks about his two boys, he wonders what he might have done differently when he was younger, before they were born, that might have tweaked his RNA profile in ways that would affect them today.
“We don’t know enough yet to develop guidance like that,” Rando said. “Maybe we will get there.”
For Hobart teacher Mary Holton, health means everything.
She started feeling the squeeze from cost-of-living pressures when fuel prices spiked again.
“Going out for just fitness alone was a bit much,”
she said.
Mary Holton says since joining the group, her fitness across the board has improved. (ABC News: Jake Grant)
Many Tasmanians are feeling cost-of-living pressures in a very physical way, with locals saying exercise routines are being dropped, health appointments delayed and wellbeing pushed to the bottom of the list as budgets tighten.
Ms Holton relies on multiple physiotherapy sessions each week, but says paid fitness classes simply are not an option.
“That costs … so to actually go to other classes as well, it’s out of my budget really.“
Ollie Mathewson conducts a free workout session. (ABC News: Jake Grant)
National data shows that almost half of Australians already fall short of minimum physical activity guidelines, and rising prices are making even basic care unaffordable for many.
Consultant clinical psychologist academic Kimberley Norris says this is exactly how unhealthy patterns begin.
“We tend to focus on the most stressful thing first … and health is one of those things we don’t think about until things go wrong,”
Professor Norris said.
Kimberley Norris says humans tend to focus on alleviating stress first and foremost, and warns de-prioritising health can become a cycle. (ABC News: Jake Grant)
For Ms Holton, going to a free workout group in her local community was a game-changer.
“Came down and absolutely loved it. It’s really nice to have a group and it just keeps growing,” she said.
Finding a free exercise group has drastically improved her health, as noted by her GP, and she is part of a growing trend.
Free exercise classes become a lifeline
At a community exercise class in South Arm, south-east of Hobart, the mood is upbeat, with laughter, movement, and a sense of relief.
Participation has more than doubled in the past year, with more than 100 Tasmanians now involved.
Trainer Ollie Mathewson said the surge was unmistakable.
“It’s free of charge for everybody … and over the last 12 months I’ve noticed a lot more people starting to come along,”
he said.
Ollie Mathewson says attendance at his classes has almost doubled over the past year. (ABC News: Jake Grant)
Across greater Hobart, free and low-cost alternatives are multiplying and include walking groups, community-run circuits, and morning and afternoon fitness meet-ups.
Tasmanians are increasingly organising their own solutions.
Mr Mathewson said connections drive outcomes.
“A lot of people talk about weight and strength, which are obviously insanely important, having other people there to push you single every week makes it a hundred times easier.“
Professor Norris said one’s health can be prioritised for free.
“What we know about health is, it’s more about sustainable wellbeing, it’s about quality of life,” she said.
“So rather than focusing on how much you can deadlift, how far you can run, it’s about how your life has improved and how close your life is to the way you want to live it.”
She said free options were vital because once people stop moving, it becomes harder to start again.
“If we develop routines in which health is not a priority, then we almost get stuck in this cycle of health always being last.“
Health appointments being delayed or dropped
For some Tasmanians, the financial pressure is forcing even tougher choices.
Amy Dakin says she can’t even think about getting a gym membership with all the other costs of living on her mind. (ABC News: Jake Grant)
Amy Dakin, who lives with a compromised immune system, often has no choice but to delay essential care.
“My health needs to be prioritised, but your bills come first, really,” she said.
Jordyn Rowbottom says she’s not the only one changing her hobbies to save on costs. (ABC News: Jake Grant)
Jordyn Rowbottom has seen the same pattern around her.
“People are being forced to cut what they can access,”
she said.
Professor Norris warns that these short-term decisions can create long-term harm, not just for individuals, but for the broader health system.
She said the combination of financial pressure and reduced physical activity would create a public health challenge.
Trainers adapting to shrinking budgets
Personal trainer Nickola Orr works with clients across different income levels, ages and needs.
She said affordability now shapes almost every program she designs.
“You want to make sure they can get as much help as they can within their price range,”
she said.
Nickola Orr is concerned about access to fitness and health services in the face of rising cost pressures. (ABC News: Jake Grant)
With the median individual spend on fitness in Tasmania sitting at almost $600 last year, Ms Orr said the warning signs were already visible.
“We’re going to see more results of long-term neglect; higher injuries, more need for mental health assistance. It’s going to snowball.”
Her concerns echo Professor Norris’s academic findings that once healthy routines break down, the consequences ripple for years.
“The changes are very small … while they add up over time, there is no immediate impact,”
Ms Orr said.
Calls for more free and low-cost options
Mr Mathewson hopes the success of free community classes will inspire governments and private operators to expand accessible fitness programs.
“More free options would be a great thing. There are a few now, but there should be more,” he said.
The Tasmanian government has said it will release its 20-year preventive health strategy this month, titled The Health Revolution.
A Department of Health spokesperson said the strategy “will address the broader social, economic, and environmental factors that influence health and wellbeing”.
“Specific issues about access to health services and programs are being considered through the Access to Health Services project, a Commonwealth-State partnership.
“The Health Revolution will complement that project by addressing the root causes of poor health and the underlying conditions to make it easier for Tasmanians to live well.“
If you’ve been faithfully logging your 30 minutes of moderate exercise most days of the week, you’re getting the recommended weekly about of cardio. But a new study1 suggests that for women in midlife, that standard benchmark may not be moving the needle on cardiovascular fitness as much as we’ve assumed. Here’s what you need to know.
EL MONTE, Calif. (KABC) — A boutique fitness gym in the San Gabriel Valley is focused on women’s empowerment, offering everything from dance fitness to pilates, yoga, zumba and circuit training. It’s called “Beastin Beauties” in El Monte.
“ Boutique fitness spaces here, it doesn’t exist here, so I needed to have this for the people in my community here, where I grew up,” said owner Jay Armada.
Members love working on their health and fitness alongside other women.
“You walk in and you feel like you’re able to let loose and inhibit it in a way that you don’t find in other places,” said member Esmeralda Cabral.
“It takes away the stresses of being in a space where you may feel judgment from others. And there’s a certain level of comfort as a woman that you wanna be able, especially if you’re starting a health journey or you’re reigniting it, you wanna have the comfort of being around under supportive women,” said member Ruby Rose Yepez, who also teaches yoga at the studio.
Women empowerment has been the theme all along, from Jay’s humble beginnings…
“ I want people to feel what I felt when I was going through my own journey. I had lost ninety-three pounds in a whole year and I just wanted everyone to feel that,” said Armada.
…to a huge setback in 2020 when the gym’s previous location burned down in a fire.
“ I thought I didn’t wanna do it anymore. Maybe it was a sign from God that you should just quit. But my community held me up and they just really made me believe in it again,” said Armada.
Now, her business is thriving, and she was just named the city’s Woman of the Year!
“ Community and connection here in this space is super, super important. Jay is not just about bringing people here for health. She brings people here to build the connections so that they feel that they’re part of a community,” said Yepez.
“You build a connection without even really trying. You’re all experiencing the same moments together. There’s always just so much fun happening,” said Cabral.
Copyright © 2026 KABC Television, LLC. All rights reserved.
-
Lifestyle3 minutes agoWe’re having a main character summer. Are you? : It’s Been a Minute
-
Technology11 minutes agoMicrosoft AI chief Mustafa Suleyman says there are three labs that matter — and he wants Microsoft to be the fourth.
-
World18 minutes agoUS ally Kuwait condemns ‘brutal and ongoing Iranian attacks’ after airport was hit
-
Politics21 minutes agoSpencer Pratt surges to runoff in LA mayor’s race after angry voters send message to Karen Bass
-
Health26 minutes agoOne extra serving of processed meat a day linked to higher cancer risk
-
Sports33 minutes agoAJ Brown trade outcome: Dianna Russini paid a heavy price while Mike Vrabel emerged unscathed
-
Technology36 minutes agoCould your Samsung phone replace your passport?
-
Business41 minutes agoRent-hike ban to protect fire victims ends despite gouging concerns
