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sperm RNA modifications and phenotypic features in the offspring,” Mansuy’s team concluded in their paper, which has not yet been peer-reviewed.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.”

As the year winds down, many people take time to reflect on what has happened over the last 12 months. You might think about your accomplishments, the challenges you faced, the things you wish had gone differently, and the changes you hope to make in the coming year. It is a natural rhythm as the calendar turns over – and with it often comes the desire for a fresh start.

But one thing people rarely reflect on (or often ignore altogether) is their musculoskeletal health. We tend to focus on appearance, weight loss, and the goals we can measure on a scale or in a mirror. What often gets overlooked, however, are the subtle physical signals that something is not quite right.

Nagging back pain is a perfect example. It is easy to brush off – easy to label as normal – and even easier to assume it will go away on its own. Back pain can slowly become something you adapt to without realizing it. Suddenly you’re adjusting how you bend. You avoid certain activities. You modify how you sit or sleep. Back pain – if you’re not careful – can quickly blend into the backdrop of your daily life.

So if there’s one thing worth leaving behind as the year closes – it’s the back pain that has been following you around for months or even decades. Despite what you may have been told – you do not have to carry this year’s pain into the next one. And when you understand how back pain actually works – you may begin to see that addressing it is one of the most important steps you can take for your overall health as you move into a new year.

Back pain rarely arrives ‘out of nowhere’

Back pain might feel sudden, but there is almost always a history behind it. Most back problems develop gradually – from months or years of poor bending habits, long hours of sitting, repetitive strain, or small compensations your body has been making without your awareness.

Until one day you sneeze, lean forward, or twist just a little too far – and suddenly you’ve “hurt your back”. People often blame the moment – but the true cause is usually what has been building underneath the surface.

The holidays (and other busy seasons) tend to make all of this worse. There is more sitting while traveling, more lifting and preparing, and more time spent on soft couches or unfamiliar beds while visiting family. The body is already managing the stress of daily life, and the extra demands of this season push it beyond what it can comfortably tolerate.

The good news? Once you understand that back pain is rarely the result of a single event “out of nowhere” – but rather the conclusion of small, repetitive microhabits over time – you can start to correct these. Small adjustments in how you bend, sit, lift, and move can make a remarkable difference.

Before you know it – not only will you have less back pain – but you’ll have far more control over it. And that kind of control changes everything.

Back pain doesn’t just ‘go away’

It is easy to assume that once the holidays are over, life will settle down and so will your pain. But pain that lingers into the new year rarely behaves that way. When your back is aggravated from mechanical or movement problems – time alone does not fix it. Rest may help temporarily, but the root issue remains. Without addressing the way you move, sit, bend, or load your spine – the pain simply returns – and sometimes for the worse.

This is also why so many people begin January full of enthusiasm only to be sidelined by February or March. They unknowingly bring unresolved back pain into their new routines. Although exercise is one of the best medicines for back pain – it’s not quite that simple.

When you don’t have any back pain – exercise is excellent prevention. But when you’re already suffering – you need very specific exercises designed to correct underlying mechanical faults before jumping into generalized strengthening.

When your foundation is not solid – even the best fitness plan can falter. Back pain influences everything. It affects how you walk, lift, twist, and breathe. It interferes with sleep, dampens motivation, and makes you cautious without realizing why.

Don’t wait for back pain to “go away” on its own – and be cautious of quick-fix New Year’s programs where you risk layering new problems on top of old ones. Ignoring what your back is telling you now could leave you worse off in 2026 than you planned.

Most back pain has a mechanical cause and a natural fix

The encouraging news is that most back pain (80%) can be resolved naturally when you understand its mechanical origins. The spine is incredibly resilient. It is designed to move, adapt, and support you through decades of life – even with arthritis or bulging discs are part of the equation.

When pain appears, it is usually signaling that something about your movement pattern needs attention. The body gives clear clues. Certain movements will feel better, others worse. How your symptoms behave throughout the day tells a more accurate story than any X-ray or MRI ever could. And once your story is fully realized – meaningful change and lasting relief become possible.

A new year is the perfect time to leave old movement patterns behind. You do not have to accept stiffness when you wake up – brace every time you bend to put on shoes – or avoid activities you enjoy because you fear making your back worse.

Small, strategic changes can make a big difference. And you don’t have to go at it alone. If leaving back pain in 2025 is one of your goals for 2026 – consider consulting with a mechanical back pain specialist who can help you sort through everything you’ve just read here. Or reach out to me personally – I’m always happy to help my loyal readers.

Dr. Carrie Jose, Physical Therapy Specialist and Mechanical Pain Expert, owns CJ Physical Therapy & Pilates in Portsmouth and writes for Seacoast Media Group. For a copy of her free self-help guide for back pain – or to get in touch – visit www.cjphysicaltherapy.com or call 603-380-7902.