High-intensity interval training (HIIT), which involves alternating short bursts of demanding exercise with easier recovery periods, may be especially helpful for older adults who want to reduce fat without sacrificing lean muscle.

In a study published in Maturitas, researchers from the University of the Sunshine Coast compared three different exercise intensities. Although participants across the groups experienced modest fat loss, HIIT stood out for its ability to reduce fat while maintaining lean tissue.

“We found that high, medium and low intensity exercises all led to modest fat loss but only HIIT retained lean muscle,” said lead author and exercise physiologist Dr. Grace Rose of the University of the Sunshine Coast.

The results highlight an important distinction in healthy aging: losing weight is not necessarily the same as improving body composition.

Six Months of Exercise Revealed a Key Difference

The Australian research team investigated how workout intensity affects body composition, meaning the proportions of fat, muscle and other tissues that make up the body.

A total of 123 healthy older adults from the Greater Brisbane region participated in the trial. Their average age was 72, and their average body mass index was approximately 26kg/m², which the researchers described as normal for adults over 65.

Participants completed three supervised gym sessions each week for six months. Each session lasted 45 minutes, and participants were assigned to high-intensity intervals, moderate-intensity exercise, or a low-intensity comparison group.

To track changes, researchers measured body composition at the beginning of the study, after three months, and again at six months. They used a specialized scanning technique that estimates fat and lean tissue throughout the body.

The findings revealed that exercise intensity made a difference.

Both high- and moderate-intensity training significantly reduced fat mass, with larger improvements than those seen in the low-intensity group. However, the two more demanding approaches differed in their effects on lean tissue.

“While moderate training reduced fat mass, it also caused a small decline in lean muscle,” Rose said.

Participants performing HIIT, meanwhile, reduced fat without experiencing the same decline in lean mass.

This could be particularly valuable later in life, when maintaining muscle becomes increasingly important for physical independence. Strong muscles help people climb stairs, get out of chairs, maintain balance, and carry out everyday activities.

One important distinction is that the scans measured lean tissue rather than muscle strength directly. Lean mass includes muscle but also other tissues and water, so changes in these measurements do not necessarily translate into equivalent changes in strength.

High-Intensity Exercise Also Reduced Abdominal Fat

The researchers found another potentially important benefit involving fat stored around the middle of the body.

“Both high and moderate intensities improved the composition of weight carried around the middle. Further analysis is needed of the low intensity results.”

The original study found improvements in visceral adipose tissue among both the high and moderate intensity groups.

Visceral fat is different from the fat that sits directly beneath the skin. It accumulates deeper in the abdomen, surrounding internal organs such as the liver and intestines.

Excessive amounts of this fat have been linked to insulin resistance, cardiovascular disease, and other metabolic problems.

According to Rose, these findings matter because body composition can influence the development and progression of chronic diseases as people age.

While body weight and body mass index provide useful general information, they do not reveal how much fat or muscle a person carries, or where that fat is stored.

Someone who loses fat while maintaining muscle may experience a more favorable change in body composition than someone who loses a similar amount of weight along with valuable lean tissue.

Still, the original researchers emphasized that the improvements were relatively small. They cautioned that the differences were not clearly clinically meaningful when compared with lower intensity exercise, particularly after accounting for measurement uncertainty.

Why HIIT May Help Aging Muscles Stay Strong

One possible explanation for HIIT’s advantage lies in the way it challenges the body.

Rather than exercising at the same pace throughout a workout, HIIT repeatedly pushes the cardiovascular system and working muscles through periods of intense effort, followed by easier activity.

University of the Sunshine Coast Associate Professor of Physiology and study co-author Mia Schaumberg explained how the training worked.

“High-intensity training in this study involved repeated short bursts, or intervals, of very hard exercise — where breathing is heavy and conversation is difficult — alternated with easier recovery periods.

“HIIT likely works better because it puts more stress on the muscles, giving the body a stronger signal to keep muscle tissue rather than lose it.”

This explanation is consistent with the idea that muscles adapt to the demands placed on them. When exercise provides a sufficiently challenging stimulus, the body has more reason to maintain the tissues needed to perform that activity.

Muscle preservation is especially important because aging is often accompanied by a gradual decline in muscle mass and strength. In more advanced cases, this can contribute to sarcopenia, a condition characterized by reduced muscle strength and quantity that can interfere with mobility and independence.

Schaumberg said the original research could help people make more informed decisions about exercise and healthy aging.

When the university publicized the findings in early 2026, she also highlighted their relevance to people setting fitness goals.

“With the festive season now behind most of us and New Year’s resolutions in full swing, this research can help inform people’s plans for healthy aging in 2026,” she said.

The research involved collaborators from UniSC’s Healthy Ageing Research Cluster and The University of Queensland.

More Recent Studies Reveal Additional Benefits of HIIT

Research published in 2026 has provided further insight into how HIIT affects older adults, although it also suggests that intense workouts are not necessarily superior in every situation.

One 2026 study, published in Medicine & Science in Sports & Exercise, investigated whether older adults could benefit from completing HIIT at home with remote supervision.

The study involved 20 adults aged 61 to 74 who exercised using a specialized machine that let them work their arms and legs without bearing their body weight.

After eight weeks of training, participants had lost an average of approximately 1.4 kilograms, or about 3 pounds, of fat mass. Their aerobic fitness also improved substantially.

Participants completed 96 percent of their scheduled workouts, and the researchers reported no exercise-related adverse events.

Although the trial was small, its findings suggest that appropriately supervised HIIT programs may offer benefits outside a conventional gym.

Another 2026 randomized trial, published in The Journals of Gerontology, Series A: Biological Sciences and Medical Sciences, compared HIIT with continuous moderate-intensity exercise in older adults living with HIV.

In that study, participants completed 16 weeks of exercise, with both groups also performing resistance training.

Unlike the original Australian study, both exercise groups experienced reductions in fat and increases in lean mass. The researchers found no statistically significant difference between the two groups in those body composition changes.

These results suggest that workout intensity is not the only factor that matters. Resistance training, which challenges muscles through weights or other forms of resistance, may also help preserve or increase lean tissue.

The populations and training programs differed, so the findings should not be treated as a direct contradiction of the Australian results.

Is HIIT Really the Best Exercise for Older Adults?

A broader scientific review published in the Journal of Clinical Medicine in August 2026 offers additional perspective.

Researchers examined 25 reports involving approximately 2,818 participants to assess how HIIT and other forms of interval training affect older adults.

The most consistent benefits involved cardiovascular fitness, including improvements in the body’s ability to use oxygen during exercise.

Some studies also reported improvements in physical function and metabolic health. However, the review did not establish that HIIT was consistently better than moderate-intensity exercise.

The researchers noted that differences between exercise programs, participant characteristics, and study methods made it difficult to identify a single optimal training approach.

Taken together, the findings suggest that HIIT can be a useful tool for healthy aging, but it is not the only way to improve fitness or protect muscle.

For adults over 65, the Centers for Disease Control and Prevention recommends a combination of aerobic exercise, muscle strengthening activities, and exercises that improve balance.

Higher intensity workouts may be appropriate for some older adults, but people who are inactive or have medical conditions may benefit from gradually building up their fitness and seeking guidance before beginning a demanding program.

The central message from the Australian study remains compelling: what happens to muscle during fat loss may be just as important as the amount of weight someone loses.

HIIT showed promise because it helped participants reduce body fat while maintaining lean tissue. Combined with newer findings, the research reinforces the value of exercise programs that support not just a lower number on the scale, but also the strength, fitness, and physical function needed for healthy aging.

The four astronauts spent 237 days in orbit, traveled more than 100 million miles, and completed thousands of trips around Earth while carrying out scientific experiments that could help shape future missions to the Moon and Mars.

NASA will host a news conference at 3:30 p.m. EDT on Thursday, Oct. 15, at Johnson Space Center in Houston, where returning crew members will discuss their experiences and research accomplishments.

“Jessica, Jack, Sophie, and Andrey spent 237 days living and working in orbit, traveled more than 100 million miles, advanced important science, and returned safely home because of the extraordinary expertise and competence of thousands across NASA, SpaceX, and our international partners,” said NASA Administrator Jared Isaacman. “Building the capability, experience, and confidence to do this repeatedly is exactly what will allow us to go farther, and I am grateful to Crew-12 and their families for their service to humanity’s greatest adventure.”

NASA Astronauts Return After 237 Days and 100 Million Miles

The returning crew included NASA astronauts Jessica Meir and Jack Hathaway, ESA (European Space Agency) astronaut Sophie Adenot, and Roscosmos cosmonaut Andrey Fedyaev.

Their spacecraft touched down in the Pacific at 8:34 a.m. PDT. SpaceX recovery teams aboard specialized vessels reached the capsule shortly afterward and brought the astronauts and spacecraft aboard.

Following routine medical evaluations, the crew members will be transported to shore before traveling to NASA’s Johnson Space Center in Houston.

“NASA’s activities supporting the International Space Station — transporting crew, conducting impactful research, and maintaining critical national assets — enable the science, engineering, and risk‑reduction needed for future missions across the solar system,” said Dana Weigel, manager of NASA’s Low Earth Orbit Program at the agency’s Johnson Space Center. “We’re grateful for the dedication across the human spaceflight team that makes this possible, and we’re thrilled to welcome Jessica, Jack, Sophie, and Andrey home.”

Over the course of their 237-day stay, the astronauts circled Earth more than 3,792 times, accumulating over 100 million miles of travel.

For Meir and Fedyaev, Crew-12 marked their second journey into space. Hathaway and Adenot, meanwhile, completed their first space missions.

The crew launched on Feb. 13 at 5:15 a.m. EST, reaching and docking with the International Space Station the following day.

Space Station Experiments Could Help Future Moon and Mars Missions

Beyond the remarkable distance traveled, Crew-12 devoted hundreds of hours to scientific investigations designed to support future human exploration and improve life on Earth.

One research project explored ways to produce stem cells in space for potential use in cell-based medical treatments. Another demonstrated technology capable of producing IV fluids on demand, an ability that could become especially valuable during long-duration missions far from Earth.

The astronauts also investigated how pneumonia-causing bacteria may contribute to lasting heart damage. Understanding this relationship could offer new insights into cardiovascular health.

Other experiments focused on nutrition in space and how individual physical characteristics may influence blood flow during spaceflight. These studies could help researchers better understand the health risks astronauts face during extended stays in microgravity.

Together, the investigations provide valuable information about keeping humans healthy beyond Earth while testing technologies that may eventually support crewed expeditions to the Moon and Mars.

Historic Spacewalks Mark Crew-12 Mission

The mission also included significant milestones outside the space station.

Meir carried out four spacewalks during Crew-12, raising her career total to seven. That achievement places her third among NASA women for the most career spacewalks, behind former astronauts Peggy Whitson and Suni Williams.

Adenot also reached a historic milestone by completing three spacewalks. In doing so, she became the first French woman to venture outside the International Space Station.

With Crew-12 safely back on Earth, NASA has completed another extended mission that combined scientific research, international cooperation, and human spaceflight experience. The knowledge gained will contribute to preparations for more ambitious journeys beyond Earth’s orbit.

NASA has highlighted four events worth watching this month, ranging from Jupiter briefly vanishing behind the Moon to shooting stars created by debris from Halley’s Comet. With crisp autumn evenings and a little luck, skywatchers can enjoy several of these displays without any special equipment.

Jupiter Disappears Behind the Moon on October 6

Before sunrise on Tuesday, October 6, skywatchers in parts of North America had an opportunity to witness an unusual celestial disappearing act. Jupiter, the largest planet in our solar system, slipped behind the Moon’s slender crescent and remained hidden for approximately an hour before coming back into view.

Astronomers call this phenomenon a lunar occultation. It happens when the Moon moves directly between Earth and a more distant object, temporarily blocking our view. Despite its mysterious-sounding name, occultation simply refers to one celestial object concealing another.

The event was visible to the naked eye, although binoculars offered a more detailed look. Observers using optical equipment could also potentially watch some of Jupiter’s moons disappear behind the lunar edge and emerge again.

Viewing opportunities depended on location, with the occultation visible across parts of eastern and central North America. The timing varied geographically, with the event occurring during the early morning hours, around 4 a.m. EDT in some locations.

Draconid Meteor Shower Peaks October 8 and 9

The next celestial attraction comes on the evening of Thursday, October 8, when the Draconid meteor shower reaches its peak. Favorable viewing beginning around 9 p.m. EDT, and the display continues into the early hours of Friday, October 9.

Unlike many meteor showers that are best observed after midnight, the Draconids offer a convenient opportunity to see shooting stars soon after nightfall. That makes them particularly appealing to casual observers who would rather not stay awake until dawn.

Conditions are especially promising this year because the Moon is approaching its new phase. With little moonlight to brighten the sky, even relatively faint meteors should be easier to detect.

The shower gets its name from Draco, a constellation representing a dragon. Although the name might sound like something from a Halloween horror story involving a certain famous vampire, it actually refers to the constellation from which the meteors appear to originate.

The Draconids are generally a modest display, typically producing only a handful of visible meteors each hour. For the best chance of spotting them, head somewhere away from bright city lights, allow your eyes to adjust to the darkness, and scan the open sky for brief streaks of light.

Orionid Meteor Shower Brings Debris From Halley’s Comet

Another opportunity to catch shooting stars arrives on October 21, when the Orionid meteor shower reaches its annual peak.

These meteors have a particularly fascinating origin. They are tiny fragments of material left behind by Halley’s Comet during its journeys through the solar system. When Earth travels through this trail of ancient comet debris, the particles enter our atmosphere at tremendous speeds, creating bright streaks of light as they burn up.

For observers in suburban areas with some artificial lighting, NASA estimates that approximately 3 to 6 meteors may be visible each hour. People watching from darker locations could see somewhat more.

The Orionids take their name from Orion, the famous hunter constellation, because their meteors appear to radiate from that region of the sky. Orion is also home to Betelgeuse, an enormous red supergiant star recognizable by its reddish appearance (but don’t say that name three times in a row!).

There is one potential obstacle to this year’s display. The Moon will be in its waxing gibbous phase, meaning more than half of its visible surface will be illuminated. Its brightness could make some of the dimmer meteors difficult to spot.

Fortunately, viewing conditions should improve after the Moon sets at approximately 3 a.m. local time. By then, Orion will also be higher in the sky, creating a better opportunity to catch meteors during the hours before sunrise.

October’s Hunter’s Moon Lights Up the Halloween Sky

October’s final major celestial highlight is the Hunter’s Moon, which reaches its full phase on October 26 in Universal Time. For observers in much of North America, the Moon will appear full on the evening of Sunday, October 25.

The name Hunter’s Moon comes from traditions associated with the changing autumn season. As crops were harvested, fields became more open, and daylight hours shortened, hunters could take advantage of the bright moonlight to locate and follow animals after sunset.

The Moon will remain a prominent feature of the night sky in the days following its full phase. As Halloween approaches, it will gradually transition into a waning gibbous Moon, with its illuminated portion slowly decreasing each night.

Its lingering glow will provide a fitting backdrop for the final evenings of October, bringing NASA’s month of celestial tricks and treats to a memorable close.

The surprise came when scientists examined a previously unknown protist called Oligohymenophorea sp. PL0344. Two genetic signals that ordinarily tell cells to stop making proteins had taken on completely different functions. Even more remarkably, the signals had been reassigned to two different amino acids, breaking a pattern scientists believed was closely linked by evolution.

The discovery, published in PLOS Genetics in October 2023, revealed an unexpected level of flexibility in one of life’s most fundamental biological systems. Subsequent research has uncovered additional genetic code variations in related microorganisms, suggesting that many more surprises could be waiting in the microscopic world.

An Accidental Genetic Discovery in a Freshwater Pond

Dr. Jamie McGowan, who was a postdoctoral scientist at the Earlham Institute, made the discovery while studying a protist collected from a pond at Oxford University Parks in England.

The project had originally been designed to test a DNA sequencing method capable of analyzing extremely small quantities of genetic material, potentially from just one cell. McGowan worked alongside scientists at the Earlham Institute and a research group led by Professor Thomas Richards at the University of Oxford.

Rather than investigating genetic code evolution, the researchers were trying to improve the tools available for studying organisms that are difficult to grow and analyze in laboratories.

But when they assembled and examined the organism’s genome, they noticed something unexpected. The protist belonged to a previously unidentified species, and its genetic instructions appeared to operate according to an unusual set of rules.

Dr. McGowan said: “It’s sheer luck we chose this protist to test our sequencing pipeline, and it just shows what’s out there, highlighting just how little we know about the genetics of protists.”

What Are Protists, and Why Are They So Unusual?

Protists are among the most diverse and least understood groups of organisms on Earth. Many consist of just one cell and are too small to see without a microscope. Familiar examples include amoebas, various algae, and diatoms, which are microscopic organisms often found in aquatic environments.

However, not all protists are tiny. The broad category also includes organisms such as kelp, slime molds, and red algae, some of which grow into large, complex structures.

The group is so varied that scientists generally define its members by excluding other major branches of life.

“The definition of a protist is loose — essentially it is any eukaryotic organism which is not an animal, plant, or fungus,” said Dr. McGowan. “This is obviously very general, and that’s because protists are an extremely variable group.

“Some are more closely related to animals, some more closely related to plants. There are hunters and prey, parasites and hosts, swimmers and sitters, and there are those with varied diets while others photosynthesize. Basically, we can make very few generalizations.”

Eukaryotes are organisms whose cells contain a nucleus, a specialized compartment that houses most of their genetic material. Humans, other animals, plants, fungi, and protists all belong to this broad category.

The organism at the center of the discovery belongs to a group of protists called ciliates. These creatures typically swim using tiny hair-like structures known as cilia, which move in coordinated patterns to propel them through water.

Ciliates are widespread in freshwater and marine environments. They are also particularly interesting to geneticists because some have evolved unusual ways of interpreting DNA instructions.

How the Genetic Code Tells Cells When to Stop

To understand why this discovery was so unexpected, it helps to know how cells turn genetic information into proteins.

DNA acts like an instruction manual, storing the information that cells need to build and maintain their structures. However, those instructions must be translated into physical molecules before they can carry out biological functions.

The process begins when a section of DNA is copied into messenger RNA, a molecule that carries genetic instructions to the cell’s protein-producing machinery.

A structure called the ribosome then reads the RNA sequence three letters at a time. Each group of three letters is known as a codon, and most codons specify one of the amino acids that serve as the building blocks of proteins.

As amino acids are connected, they form a chain that can fold into a three-dimensional structure. The resulting protein may function as an enzyme, provide structural support, transport molecules, or perform countless other cellular tasks.

In DNA notation, a protein-coding sequence commonly begins with a start codon (ATG) and ends with a stop codon (normally TAA, TAG, or TGA).

These stop codons work like punctuation marks. They tell the ribosome that it has reached the end of the instructions for a particular protein and should release the completed chain.

When the instructions are copied into RNA, the letter T is replaced by U. Consequently, the corresponding stop codons in RNA are written as UAA, UAG, and UGA.

Across most forms of life, these signals have maintained the same basic functions for an extraordinarily long period of evolutionary history.

But nature has occasionally found ways around the usual rules.

Scientists Find Two Genetic Stop Signals With Different Meanings

Researchers have known for decades that some organisms use modified versions of the genetic code. These variations are uncommon across life as a whole, but ciliates are particularly rich in examples.

In certain ciliates, stop codons have evolved to specify amino acids instead of terminating protein production.

Until relatively recently, one pattern appeared especially consistent. Two of the conventional stop codons, TAA and TAG, almost always retained the same meaning. When their functions changed, both generally came to specify the same amino acid.

This suggested that the two signals were constrained to evolve together.

“In almost every other case we know of, TAA and TAG change in tandem,” explained Dr. McGowan. “When they aren’t stop codons, they each specify the same amino acid.”

The genome of Oligohymenophorea sp. PL0344 told a different story.

Instead of functioning as stop signals, TAA and TAG appeared to encode entirely different amino acids. TAA specified lysine, while TAG specified glutamic acid.

Both amino acids are common components of proteins, but they have different chemical properties and biological roles.

Meanwhile, TGA remained the organism’s only conventional stop codon.

The findings represented the first reported example of a genetic code in which both TAA and TAG had been reassigned to encode two different amino acids.

That distinction matters because it shows that the evolutionary relationship between the two codons is not as restrictive as scientists had assumed.

“This is extremely unusual,” Dr. McGowan said. “We’re not aware of any other case where these stop codons are linked to two different amino acids. It breaks some of the rules we thought we knew about gene translation — these two codons were thought to be coupled.

How This Microscopic Organism Makes the Unusual Code Work

Further investigation revealed clues about how the protist manages to function with its unconventional genetic instructions.

The researchers identified specialized transfer RNA genes associated with the reassigned codons. Transfer RNA molecules act as interpreters during protein production, helping match the instructions in messenger RNA with the correct amino acids.

Their presence supported the conclusion that the unusual genetic code was a genuine feature of the organism rather than a sequencing error.

The team also found an unexpectedly high number of TGA stop codons in DNA regions immediately following protein-coding sequences.

These additional stop signals could act as a backup system. If the ribosome accidentally continues reading beyond the intended end of a protein, a second stop codon may prevent it from extending the protein too far.

That protection could be particularly valuable in an organism that relies on only one of the three conventional stop codons.

Although the researchers could not establish exactly how the unusual code evolved, the findings demonstrated that the machinery responsible for translating genetic information can be far more adaptable than previously appreciated.

Follow-Up Research Reveals More Genetic Code Surprises

The original discovery also opened the door to a broader question: How many other microorganisms are using genetic codes that scientists have not yet recognized?

In December 2024, McGowan and colleagues published additional findings in PLOS Genetics showing that unusual genetic code changes had occurred independently in several other ciliate lineages.

The team investigated genetic information from a group of ciliates known as Phyllopharyngea, including genomic data gathered through the TARA Oceans project, an international effort to study marine life and its genetic diversity.

Their analysis identified three previously uncultivated ciliate species in which UAG, normally a stop codon, appeared to specify leucine instead.

These organisms came from samples associated with the Arctic and Southern Oceans.

The researchers also examined existing genomic datasets and identified two additional ciliates, Hartmannula sinica and Trochilia petrani, in which UAG appeared to encode glutamine.

Evolutionary comparisons suggested that these changes arose independently on at least three occasions.

Importantly, the genetic codes were not identical to the unusual system found in Oligohymenophorea sp. PL0344. In the five ciliates examined in the 2024 research, UAA remained a stop signal while UAG had acquired a different meaning.

Even so, the findings provided further evidence that these two genetic signals do not always have to evolve together.

Rather than being an isolated curiosity, the original discovery had helped illuminate a much wider pattern of genetic code flexibility among ciliates.

Scientists Are Still Uncovering Hidden Protist Diversity

The search for unexpected biology in microscopic organisms has continued beyond the genetic code itself.

In March 2026, researchers from the Earlham Institute and the University of Oxford reported another discovery made possible by techniques designed to sequence individual cells.

Their study, published in Microbial Genomics, investigated Bodo, a group of common protists found in freshwater, brackish water, and soil.

By analyzing just seven uncultured cells, the scientists identified three previously unrecognized evolutionary lineages, each associated with its own distinct bacterial partner living inside the organism.

The work did not demonstrate the same genetic code changes found in PL0344. Instead, it showed how much biological diversity can remain hidden when researchers rely primarily on organisms that are easy to cultivate in laboratories.

Together with the genetic code discoveries, these findings demonstrate the value of examining microorganisms that have received relatively little scientific attention.

Better sequencing technologies could reveal additional unconventional genetic codes, unexpected relationships between organisms, and previously unknown ways that cells function.

Nature May Have More Genetic Rules to Break

For scientists, unusual genetic codes offer more than biological curiosities. They provide opportunities to investigate why the genetic code is so consistent across most forms of life and how evolutionary changes can sometimes alter its fundamental instructions.

Understanding these natural variations could also inform efforts in synthetic biology, where researchers attempt to modify genetic codes to give cells new capabilities or enable them to produce proteins with unusual properties.

However, the evolutionary forces responsible for the extraordinary diversity of genetic codes among ciliates remain incompletely understood.

What began as a routine sequencing experiment ultimately revealed that even some of biology’s most familiar rules have remarkable exceptions.

As McGowan observed:

“Scientists attempt to engineer new genetic codes — but they are also out there in nature. There are fascinating things we can find, if we look for them.

“Or, in this case, when we are not looking for them.”