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How Dad’s Fitness May Be Packaged and Passed Down in Sperm RNA | Quanta Magazine

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sperm RNA modifications and phenotypic features in the offspring,” Mansuy’s team concluded in their paper, which has not yet been peer-reviewed.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

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“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.

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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.”

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Fitness

Air Force revises physical fitness program, score charts to boost airmen health

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Air Force revises physical fitness program, score charts to boost airmen health

The U.S. Air Force updated its physical fitness program and score charts for the fitness tests to boost the long-term health of airmen.

The modernized program utilizes a more thorough assessment model to strengthen warfighter readiness by motivating airmen to build more sustainable fitness habits for the duration of their careers, according to a Feb. 27 release.

“This update is not just about increasing the physical fitness test standards; it’s about ensuring our warfighters are fit, ready, and prioritizing their long-term health,” Air Force Chief of Staff Gen. Ken Wilsbach said in the memo.

The updated score charts will have increased minimums for each scored component and separate charts are now available for Occupationally Specific Physical Fitness Assessments as well.

A baseline window for airmen to take the diagnostic tests will begin March 1, but scoring won’t become official until July 1, per the statement.

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This gives the airmen time to adjust their training focus as needed before the official scoring date. The baseline period is also meant to produce data to ensure that the new program is implemented in a fair, accurate and effective manner across the Air Force.

“The baseline period will also provide the data required to assess and refine score charts in advance of full implementation of the new standards,” the statement says.

Airmen who complete the Physical Fitness Readiness Assessment during the baseline period can use that diagnostic score as their official fitness test score, according to the release.

Body composition will return as a scored component in the assessment, but airmen can elect to take it out of the test up to five days before testing the remaining components.

The release states that resources are made available to support the force through the transition, like trained experts that will instruct airmen through safe conditioning and a playbook that gives guidance on workouts, recovery and nutrition.

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Earlier this year, the force announced that airmen can choose between a 2-mile run or the 20-meter High-Aerobic Multi-shuttle Run for their fitness tests every six months, following the “Culture of Fitness” initiative last September to encourage airmen and Space Force guardians to improve their physical fitness.

The statement says that the certification of the 2-mile run is in progress to ensure that all Air Force tracks meet official standards, and final measurement specifications will be published in the fitness program guide.

As announced in January, an airmen’s fitness assessment scores will become part of their annual evaluation to “incorporate a full picture of an individual’s performance and contributions.”

Cristina Stassis is a reporter covering stories surrounding the defense industry, national security, military/veteran affairs and more. She previously worked as an editorial fellow for Defense News in 2024 where she assisted the newsroom in breaking news across Sightline Media Group.

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Study finds 5 more minutes of exercise could reduce your risk of death by 10%

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Study finds 5 more minutes of exercise could reduce your risk of death by 10%

The universal quest for immortality continues, and new research has hinted at a small lifestyle change that could reduce overall death rates in countries if we start taking our movement more seriously. 

Conducted by a global research team, the study named ‘Deaths potentially averted by small changes in physical activity and sedentary time: an individual participant data meta-analysis of prospective cohort studies’ was published in The Lancet and suggested that adding five more minutes of physical exercise a day to your life could reduce death rates by 6 per cent. 

Conducted on cohorts wearing on-person devices from Norway, Sweden and the USA, scientists analysed activity and sedentary levels to deduce what was causing higher death rates and found that a little change could go a long way.

With the help of the study’s author and additional experts from the field, we delved into the details and uncovered exactly what we need to do to make sure we are maximising our health before it’s too late. 

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A little change makes all the difference 

We already know that we should all be getting out and exercising to ensure everything in our bodies is running smoothly, but just how important is that daily movement and could it be contributing to national mortality rates? 

Professor Ulf Ekelund works in the Physical Activity and Health department at the Norwegian School of Sport Sciences and was one of the authors of the study. He broke down the data for HELLO!

The professor explained: “We estimated the number of deaths potentially prevented by five and ten-minute increases in moderate intensity physical activity if all individuals in the population adhered to this increase. 

“We analysed the data using two different approaches: 

  1. ‘High-risk approach’ comprising the least active 20 per cent of the population 
  2. ‘Population approach’ comprising 80 per cent of the population (excluding the most active 20 per cent).

He continued: “We found that six per cent and ten per cent of all deaths might be prevented in the two different scenarios, respectively, if all individuals made these changes. 

“If an individual is completely inactive, every little move counts. For example, the least active 20 per cent in our study sample were only active for an average of about two minutes per day of moderate intensity. If all these individuals increased their activity by five minutes per day, it might reduce the number of deaths by six per cent annually.”

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Dr Darren Player, a professor in Musculoskeletal Bioengineering at University College London, who was not involved in the study, shared his interpretation of the data with us and added: “The key finding was that an increase in Moderate-to-Vigorous Physical Activity (MVPA) by only five minutes per day for the least active individuals prevented 6 per cent of all deaths. This effect could extend to as much as 10 per cent in all individuals, except for those who are already very active.” 

© Getty Images
Adding five minutes of exercise on to your day could have massive results

Exercise versus moderate intensity 

In terms of how to achieve the correct level of activity and movement, we have to understand the difference between physical activity and moderately intense movement. They are different and will yield different results. 

Professor Ulf explained: “There is a clear distinction between moderate intensity activity and exercise. Brisk walking is an excellent type of moderate intensity, whereas exercise is defined as something people do with the purpose to enhance fitness and/or health. It is structured and repetitive. Exercise is only a small proportion of all the physical activity people do. 

“Physical activity [PA] is any bodily movement that increases energy expenditure above resting levels. It can be conducted with different intensities from very low to very strenuous. Exercise is a subset of PA which is planned, structured and done with a specific purpose.” 

Woman and her dog running towards the sunset on a country road© Getty Images
It matters what kind of exercise you do, so we need to understand the difference between physical exercise and intense movement

Could any of this add years onto our lives? 

While this study was specifically about reducing death rates through exercise and movement, it made us wonder how it would affect the number of years we could all expect to live. Would incorporating an extra five minutes of movement add any time to the general life expectancy? 

Dr Darren referred to data from the UK Biobank to share his estimations. He said: “This is quite a difficult question to answer, but there is some evidence. The following paper suggests that there could be an increase in life expectancy of 0.9 years for inactive women and up to 1.4 years for inactive men. 

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“The increases are dependent on the nature of physical activity, with higher intensity and greater volume (total amount of exercise) being the key factors. This is a large UK Biobank study, which does have some strengths for the analyses.” 

He continued: “However, the factors that contribute to life expectancy and mortality are complex and varied, with further studies required to understand the picture fully. Particularly, the effect of resistance training combined with other forms of physical activity is likely to have a greater effect than one type of activity alone. Further research is required in this area to provide suitable evidence.” 

What type of exercises can I do during my five extra minutes a day? 

According to the NHS, there are a variety of movements that you can incorporate into your routine to make sure you are hitting the target of five extra minutes of exercise per day to increase your longevity. 

These range from simple activities like making a cup of tea to pushing a lawnmower and dancing around your living room for fitness, depending on the intensity you are able for. While the study suggested five minutes of moderate intensity exercise, the health service broke down its recommendations into sections based on vigour:

Light activity: 

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  • Getting up to make a cup of tea
  • Moving around your home
  • Walking at a slow pace
  • Cleaning and dusting
  • Vacuuming

Moderate activity:

  • Walking for health
  • Water aerobics
  • Riding a bike
  • Dance for fitness
  • Pushing a lawnmower
  • Hiking

Intense activity: 

  • Running
  • Swimming
  • Football
  • Hiking uphill
  • Martial arts

It also suggested some easy-to-do strength exercises that involve using a kitchen chair or filled bottles of water as props:

  • Sit-to-stand 
  • Mini squats 
  • Calf raises 
  • Standing sideways leg lift 
  • Standing leg extension 
  • Wall press-up 
  • Bicep curls 
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Fitness

Fitness Class Volume Tied to Exercise Intensity Perception

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Fitness Class Volume Tied to Exercise Intensity Perception

About The Study: In this comparative effectiveness study, reducing music volume in group fitness classes did not lead to meaningful reductions in perceived exertion and may reduce the risk of noise-induced hearing loss. These findings support implementing safer sound practices in fitness environments and underscore the need for increased awareness and education on hearing protection.

/Public Release. This material from the originating organization/author(s) might be of the point-in-time nature, and edited for clarity, style and length. Mirage.News does not take institutional positions or sides, and all views, positions, and conclusions expressed herein are solely those of the author(s).View in full here.

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