Fitness

We can’t all be astronauts, but the Artemis II crew has fitness lessons for everyone

Published

3 months ago

April 10, 2026

We can’t all be astronauts, but the Artemis II crew has fitness lessons for everyone

The Artemis II crew — Christina Koch (left), Jeremy Hansen, Victor Glover and Reid Wiseman — have to share tight quarters aboard the Orion spacecraft on their way home. But even with limited space, they can still get a solid workout in — thanks to a very special piece of equipment.

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NASA

Even a few days away from Earth can significantly alter the human body. Without the constant pull of gravity on the skeleton, muscle and bone can quickly atrophy. To combat this immediate physical decline, the four astronauts aboard Orion on the Artemis II mission are using a specially designed machine known as the flywheel.

In a video blog posted before the crew launched, Canadian astronaut Jeremy Hansen compares the flywheel to a rowing machine. “Like a cardiovascular workout where you row at a lower resistance and a fast pace,” Hansen explains as he demonstrates the flywheel’s functionality. Astronauts strap their feet onto a small platform and pull on a handle connected to a cable. Pulling spins a flywheel. It works like a yo-yo, according to NASA — astronauts get as much resistance as they put into it.

The Artemis II crew exercises on Orion using a flywheel, a simple cable-based device for aerobic and resistance workouts.
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The flywheel is small, not unlike an extra large shoebox. Working in Orion’s tight quarters — only 316 cubic feet , about the size of a smallish bedroom — engineers had to design this device to perform with utmost efficiency, so that it can both provide a cardiovascular workout and resistance exercises up to 400 pounds. Astronauts can use it to do weightlifting moves like squats, deadlifts and curls.

Before the astronauts, there were the pillownauts

The flywheel has been years in the making. Jessica Scott, an exercise physiologist at Memorial Sloan Kettering Cancer Center, worked on early prototypes for NASA, anticipating that astronauts would be vulnerable to rapid muscle atrophy without physical exertion.

The moon, seen here backlit by the sun during a solar eclipse on Monday, is photographed by one of the cameras on the Orion spacecraft’s solar array wings

Scott compares ten days in space to ten days in bed. Atrophying for that amount of time, says Scott, “You would feel very weak and your muscles start to lose size very quickly.” The heart, she stresses, is especially vulnerable with this decline in strength.

When recruiting people to study these early flywheel prototypes, says Scott, researchers looked for 30 subjects willing to lie in bed for 70 days. She and her colleagues weren’t sure they would be easy to recruit.

Turns out, people were eager to spend hours a day reclining in the name of science.

In this handout image provided by NASA, a view of the moon taken by an Artemis II crewmember through the window of the Orion spacecraft on Friday, the third day of the mission.

“We had over 10,000 people apply for 30 positions,” says Scott.

They called themselves the “pillownauts.”

Researchers divided these participants into different groups. Some stayed in bed all day. Some of them broke their bed rest in order to work out on a more traditional suite of exercise equipment, and some of them used the flywheel. The goal was not to improve fitness, but to prevent declines.

The flywheel, says Scott, delivered the results researchers were hoping.

“What was really exciting was that the small device could prevent the declines, the same amount that a full gym could do,” she says.

Other missions — like those aboard the International Space Station — have full suites of exercise equipment. The flywheel has not yet been tested for longer durations, but Scott says she’s hopeful it could also provide fitness for astronauts in longer periods of gravity deprivation.

Not everyone’s an astronaut, but everyone ages

Even for people who are not planning on orbiting the moon — this research has important implications, says Thomas Lang, a radiologist who studies bone and muscle loss and has worked with NASA on exercise science for previous missions.

“You start childhood and then as you grow your bone density and mass reach a peak,” says Lang, “in your late twenties or early thirties.”

Those who are lucky to live to old age, he says, will experience hormonal changes that lead to bone loss over time. For women, that escalates sharply in menopause. “That’s a big whopping decline,” says Lang.

Men’s decline may not be as dramatic, says Lang, but they are also vulnerable, especially as they live into their 70s and 80s.

NASA researcher Jessica Scott is also hopeful this work could have broader applications for the general public. Few of us will travel to space, but many of us can relate to dealing with time and space constraints when it comes to exercise, says Scott.

“One day we could all be having our own flywheel,” she says — something small enough to fit under a desk at work, or in the corner of an office.

After his first 30-minute aerobic session with the device, astronaut Reid Wiseman said he was happy to report that in addition to providing a good workout, he was pleased the flywheel didn’t drive his roommates too crazy. No one had to wear ear plugs to block out the sound.

“ It is a really good piece of gear and we can actually get a nice workout,” says Wiseman. “I look forward to the next time I get to try a resistance workout.”

Fitness

Why 21-15-9 Might be the Smartest Workout Format in Fitness – and How to Use it to Drive Muscle Growth

Published

4 hours ago

July 5, 2026

Press Room

Why 21-15-9 Might be the Smartest Workout Format in Fitness – and How to Use it to Drive Muscle Growth

CrossFit means a lot of things to a lot of people – because it’s made up of a lot of things.

Since the rise of the fitness giant, countless brands, events and training methods have sprung up around it – not claiming to be CrossFit, but looking suspiciously CrossFit-esque.

There are, however, a handful of things that are uniquely CrossFit: the ‘Girls’ benchmark workouts. The Hero WODs and, of course, its signature rep schemes.

Chief among them is ’21-15-9′.

The 21-15-9 rep scheme may just be the single most CrossFit thing in existence. But what exactly is it? Where did it come from? And why might it actually be better at building muscle in a hurry than its conditioning roots would have you believe?

Let’s have a look.

What Is 21-15-9?

If you’ve never encountered it before, the format couldn’t be simpler. Choose two exercises (occasionally more) and perform 21 reps of each, then 15 reps of each, then nine reps of each, completing the entire workout as quickly as possible – with good form.

Probably the best-known example is ‘Fran’: 21 thrusters and pull-ups, followed by 15 of each, then nine. On paper it doesn’t look especially intimidating. In practice, it’s one of the most feared benchmark workouts in fitness.

Where Did it Come From?

Unlike many modern training methods, 21-15-9 didn’t come out of a study. It came from the gym floor.

CrossFit founder Greg Glassman has explained that the format emerged through years of coaching and experimentation in the 1990s. Rather than chasing a perfect sets-and-reps prescription, he was looking for a workout that allowed athletes to maintain a high power output from start to finish.

The thinking is surprisingly elegant. You begin with 21 reps while fresh. By the time you reach the set of 15, your ability to produce force has already fallen. By the final nine, you’re significantly more fatigued – but the workload has dropped by almost the same amount.

Instead of grinding through increasingly miserable sets of the same length, the workout ‘meets you where you are’, reducing the work required as your capacity declines. The result is a workout that encourages you to keep moving instead of standing around trying to recover.

The numbers themselves are also remarkably practical. Forty-five total reps per movement provides plenty of training volume without turning the session into an endurance slog, while every set divides neatly into thirds if you need to break it up.

(Although I’ve got to be honest, I’m a 20-15-10-5 man myself, just for the sake of round numbers.)

Why Does it Work So Well?

Although there isn’t research showing that 21-15-9 is somehow the magic formula, there are obvious reasons why it consistently produces brutally effective workouts.

Descending reps help maintain intensity. As fatigue accumulates, reducing the target allows movement quality, bar speed and overall work rate to stay higher than they would if you simply repeated the same number of reps over and over.

It also tends to land in a physiological sweet spot. Most 21-15-9 workouts take between three and eight minutes, depending on the movements and the athlete. That’s long enough to create a serious cardiovascular challenge while still requiring meaningful force production throughout. You’re taxing your anaerobic systems hard while relying on your aerobic system to help you recover just enough to keep going.

Finally, there’s the psychological trick. The hardest-looking part comes first. Once you’ve survived the opening 21, every remaining round appears more manageable. ‘Only 15 left.’ Then, ‘Just nine.’ In reality, you’re becoming more fatigued with every rep, but the shrinking target keeps you attacking the workout instead of pacing too conservatively.

Why it Might be Surprisingly Good for Building Muscle

Perhaps the biggest misconception about 21-15-9 is that it’s ‘just cardio with weights’.

Choose the right load and something interesting happens. Very few athletes complete every round unbroken. Instead, the workout naturally evolves into a series of short, broken sets separated by only a few seconds of rest.

Your 21 might become 11-5-5. Your 15 becomes 8-4-3. Your final nine might stay unbroken – or become 5-4.

In effect, you’ve accidentally turned the workout into a form of rest-pause training.

Those brief pauses allow just enough recovery to squeeze out more high-quality repetitions before fatigue catches up again. By the latter stages of each mini-set, you’re repeatedly working very close to failure, recruiting the high-threshold motor units with the greatest potential for muscle growth.

It’s a similar principle to rest-pause training, myo-reps and cluster sets: all methods used to accumulate hypertrophy-friendly volume while keeping the load relatively heavy and the rest periods brutally short.

You’re basically speed-running a large number of hard, growth-stimulating reps in a very small window of time. Could this help explain why elite CrossFit athletes often carry an impressive amount of muscle despite spending relatively little time performing traditional bodybuilding splits?

It’s certainly plausible, although the ‘elite’ part often selects for athletes with the greatest muscle-building potential.

Much of their training isn’t simply conditioning. It’s high-density resistance training performed under accumulating fatigue, with only fleeting recovery between efforts. In other words, they’re often doing something bodybuilders have deliberately programmed for decades: packing a lot of hard work into a very short period of time.

That’s not to say 21-15-9 is superior to a well-designed hypertrophy programme. If your sole goal is building muscle, there are more efficient ways to do it.

But if you’re looking for a workout that develops fitness, tests your mettle and still provides a meaningful stimulus for strength and size, it’s easy to see why this deceptively simple rep scheme has remained one of CrossFit’s defining fingerprints for more than 20 years.

Best Bodyweight 21-15-9 Workout: ‘JT’

If you’re looking for an interesting twist on the 21-15-9 format, look no further than Hero WOD ‘JT’, which concentrates the muscle-building potential of the format into a brutal upper-body workout.

Created in honour of Petty Officer 1st Class Jeff Taylor, who was killed in Afghanistan in 2006, the workout strips away barbells altogether and relies solely on three bodyweight movements:

21-15-9 reps of:

Don’t let the lack of equipment fool you. The volume – 45 reps of each movement, 135 reps in total – combined with the descending rep scheme makes this a brutal upper-body test, hammering the shoulders, chest and triceps while demanding serious muscular endurance.

Better still, it perfectly demonstrates one of the biggest strengths of 21-15-9. As fatigue mounts and the sets naturally fragment, the workout begins to resemble one giant rest-pause set, allowing you to accumulate a huge number of hard, near-failure reps in less than 10 minutes.

If your goal is building an impressive upper body while developing serious work capacity, there are few bodyweight workouts that deliver quite so much bang for your buck, making ‘JT’ one of my personal favourites.

fitness magazine cover featuring a muscular man with kettlebells

If there’s one thing Kori Sampson knows, it’s how to optimise your body composition for performance. To tap into his knowledge as an elite athlete and coach, we asked him to create a 4-week plan to help you move faster, recover quicker and keep pushing when the fatigue sets in – all while improving your muscle-to-fat ratio.

Ready to build muscle, burn fat and come out the other side looking, feeling and performing better? Click here to get 14 days of free access to the plan via the Men’s Health app.

Fitness

10 minutes of swimming might not sound worth it – but I tried it for 2 weeks and found the benefits of a quick dip

Published

14 hours ago

July 4, 2026

Press Room

10 minutes of swimming might not sound worth it – but I tried it for 2 weeks and found the benefits of a quick dip

The concept of ‘exercise snacking’ has never been more popular. Not only is it convenient and accessible, but there is solid scientific evidence that short bursts of physical activity can yield real benefits for our health. But can a swimming workout be an effective ‘exercise snack’?

A study published in the European Heart Journal found that just 15 to 20 minutes of vigorous physical activity a week (almost as low as two minutes a day) was enough to significantly lower the risk of heart disease, cancer and early death. The study defined vigorous activity as any exercise that leaves you out of breath and raises your heart rate, including swimming.

But does ‘exercise snacking’ really work in the pool? Unlike a short run, walk, or online workout at home, going for a swim requires a bit of effort beyond the swim itself, so we often want to spend longer in the pool to make the most of it. However, head of swim for David Lloyd Clubs, Nuala Muir-Cochrane, believes short swims are worth it: “If you only have 10 minutes, consistency matters more than volume. Even two or three short swims per week can improve swim fitness noticeably,” she says.

With that in mind, I added some 10-minute swims to my routine of strength training and yoga workouts for two weeks to see if it made any difference to my health and fitness. Here’s what I discovered, plus what experts told me about optimising a short swim to either energise, recover or relax.

Benefits of 10-minute swimming workouts

1. Aids muscle recovery

To make the most of my short pool sessions, I often paired them with a gym visit, realising that I’ll need a post-workout shower anyway, so I may as well take a dip first. According to Francesca Bagshaw, performance physiologist at Nuffield Health’s Manchester Institute of Health and Performance, a short swim is perfect for recovering after the gym, a run or exercise class because it combines low-impact movement with increased circulation.

“After a hard session, muscles can feel stiff and fatigued due to microscopic muscle damage, inflammation and metabolite build-up,” she explains. “Gentle swimming helps stimulate blood flow without placing additional mechanical stress on joints and muscles,” Francesca recommends keeping the intensity low to moderate if recovery is your goal, to promote mobility, relaxation and circulation, without additional fatigue.

Samantha Russo, master swim coach for Virgin Active, adds, “In the pool, the water holds most of your bodyweight, so your joints get a break, but your muscles are still working gently through a big range of motion. Because water gives soft resistance in every direction, an easy swim is like active stretching with a built-in massage for the muscles, so you loosen up rather than lock up.”

2. Supports muscle building

Water is around 800 times denser than air, making swimming (or any movement in water) an effective resistance workout. Your muscles need to work harder to propel the body through the water, and multiple muscle groups will be involved, including those in your arms, legs, back and core.

My fortnight of short swims probably didn’t help me gain muscle – the resistance of the water never changes, so practising progressive overload (gradually increasing the weight, as I can in the gym) isn’t possible. I would have to either increase my speed, distance or duration to do this. But I felt that my short swims did support gains from strength training in the gym. Maintaining muscle has been useful for staying strong, not just for my gym workouts, but also for my yoga classes and occasional run.

10 minutes might not seem like a long time, but if you’re headed for the shower anyway, why not throw in a quick workout?

(Image credit: Kerry Law / Future)

3. Boosts energy levels

While it isn’t my preferred timeslot, I would sometimes schedule a short, pacier swim in the morning to boost my mental and physical energy before work. If you prefer morning workouts, you might find that adding a short, fast swim after the gym or an exercise class will energise you for the day ahead.

Samantha is a fan of morning swims: “In the morning, your circulation and nervous system are still in ‘low power mode’, and a short swim acts like a full-body wake-up call,” she says. “The cold water stimulates your skin and nerves, your breathing and heart rate increase, and more oxygen-rich blood is pushed to your brain and muscles. That mix of oxygen, movement and endorphins clears brain fog and lifts your mood far better than a cup of coffee.”

Francesca adds, “For best results, morning swims should be kept relatively short and refreshing rather than exhaustive, particularly before work or further training later in the day.”

4. Lowers stress levels

Much has been discovered about the effects of immersion in water, and how it can induce an ultra-calming ‘blue mind’ state. This is partly why I favour an evening swim, not just to avoid the busiest times at the pool, but to lower my cortisol levels and put a full stop to the day. This can have a calming effect on the nervous system, explains Francesca.

“Steady, rhythmic swimming encourages controlled breathing patterns and can help shift the body toward a more parasympathetic, ‘rest and digest’, state. This reduces physiological arousal and can lower stress levels after a busy day,” she says.

“Warm or temperate water can reduce muscle tension and promote peripheral vasodilation [widening of the blood vessels], helping the body feel physically calmer. The repetitive nature of swimming has a meditative effect for many people, supporting mental decompression and reduced cognitive stress.”

Samantha adds that some may find evening swims contribute to a better night’s sleep: “Your core body temperature rises slightly in the water, then drops as you shower and dry off, and that drop is a natural signal to your brain that it’s time for bed.”

5. Burns calories

The number of calories you burn during a swim will depend on various factors, including the duration, distance, intensity and your bodyweight. For example, according to Harvard Medical School data, someone who weighs 155lb could expect to burn approximately 200 calories over a 30-minute low-intensity swim, rising to 360 calories for a high-intensity 30-minute swim.

Just 10 minutes of swimming will amount to a third of that calorie burn, but the ‘afterburn’ – or excess post-exercise oxygen consumption (EPOC) – may help burn a few more. The ‘afterburn’ concept suggests that we consume more oxygen to help our bodies restore and repair following intense exercise, essentially burning calories at a greater rate. However, research suggests this amounts to just a handful of extra calories burnt.

However, I can be confident that spending an extra 10 minutes swimming in the evening burns more calories than my alternative (usually sitting on the sofa watching TV). It’s the same for a 10-minute walking workout.

10-minute swimming workouts to try

Multi-stroke sprint swimming workout

Nuala recommends this swim workout for beginner-intermediate level swimmers. “It improves cardiovascular fitness without the need for a long session, while using different muscle groups through the stroke changes. The easy swim at the end helps recovery and reduces stiffness,” she says.

How to do it:

For the first five minutes, alternate between front crawl, breaststroke and backstroke for one length each.
On every fourth length, sprint at your near maximum effort. Maintain controlled technique even when swimming faster.
For the final five minutes, cool down with gentle continuous swimming with whichever stroke feels most relaxed. Focus on long strokes with steady breathing and low effort.

Maintaining form is crucial, says Nuala: “For front crawl, keep your head still and look slightly downward rather than forwards; in breaststroke, glide briefly after each kick rather than rushing the strokes; and for backstroke, keep your hips high and do small continuous kicks.”

Varied swimming workout

Cheryl Pottinger, swim teacher for Better, suggests this 10 minute routine which goes up and down the speed scale over 300m (in a standard 25m pool).

How to do it:

Warm up with one length of front crawl, followed by one length of breaststroke at normal pace.
For your main set, swim front crawl with a 10 second rest after each practice, starting with one length at your maximum speed.
Follow it with two lengths at 80% of your maximum speed.
Shift down a gear for the next three lengths at normal pace.
Swim the next two lengths at 80% of your maximum speed.
Finish this section with one length at maximum speed.
Cool down with one length in a stroke of your choice at normal pace.

Recovery swim

As a gentle short swim to aid relaxation after a gym session, Cheryl recommends this sequence. It incorporates the lesser known side stroke, which is relaxed, energy efficient and builds core stability as it forces your midsection to engage as you balance on one side.

How to do it:

Warm up with one length of front crawl and one length of breaststroke at a relaxed pace.
Swim the next two lengths in side stroke, one length on the right side and one on the left. This stroke requires balancing on one side of the body, reaching forward with one arm while the other pulls back, and scissor kicking the legs. “Focus on the power in the muscles during the pull and kick, and the stretching of the muscles during the glide,” says Cheryl. Watch a demo here.
Finish with one length of steady-paced breaststroke, and a final length of head-first sculling (lie on your back using your arms to propel you backwards).

Tips for making the most of a 10-minute swimming workout

Make it your post-gym habit: All the effort involved in travelling to and from the pool, let alone changing in and out of clothes, may not feel worth it for just 10 minutes in the pool. So, I often tacked it onto the end of my regular gym session. If your gym has a pool, make the most of it and view it as part of your workout ‘cool down’ and recovery before showering and heading home.
Tailor your swim to the time of day: There are still benefits to be had if you take a relaxing swim in the morning, or a higher intensity swim in the evening, but you might be working against your energy levels. As Francesca recommends, a pacier swim early in the day can boost alertness, while a lighter intensity swim in the evening can aid post-workout recovery and sleep.
Choose quieter pool times: This goes for however long you wish to spend swimming, but having a lane all to yourself allows you to follow a plan without compromise. I find evenings are best for me but check your local pool timetable to avoid sharing space with unexpected aqua aerobic classes or school swimming lessons.
Bring a poolside kit bag: With just 10 minutes in the pool, you don’t have time to keep nipping back to your locker to fetch forgotten kit. Have a small kit bag pre-packed with anything you might need (think spare hairclips and hairbands, anti-fog goggle spray, kickboard and pull buoy if you’re using them), and keep it at the end of your lane (make sure it isn’t a trip hazard).

Fitness

The Fitness Secrets of Wimbledon’s Top Tennis Pros

Published

1 day ago

July 4, 2026

Press Room

The Fitness Secrets of Wimbledon’s Top Tennis Pros

While many of us are far from becoming top-ranked athletes, there’s plenty to learn from the pros when it comes to optimising our health and fitness. From Janik Sinnner’s muscle-building techniques to Novak Djokovic’s devotion to longevity, dig into these tennis pros’ secrets for peak performance.

Joris Verwijst/BSR Agency//Getty Images

CARLOS ALCARAZ

Fitness Game Changer:

Sand Footwork Drills

Any pro tennis player has to play with agility, but Alcaraz can move. To do so at a high level, the 21-year-old performs lateral movement drills in the sand, teaching his feet to drive up from an unstable surface. This can help prevent ankle injuries and build strength in his calves and shin muscles.

Jose Breton/Pics Action/NurPhoto//Getty Images

JANNIK SINNER

Fitness Game Changer:

Landmine Rotations

Sinner has historically lacked the physical prowess of his competitors, so the 23-year-old has gone all in on strength and mobility work. He does landmine rotational exercises such as the hollow body landmine press, which builds upper-body power.

Lintao Zhang//Getty Images

NOVAK DJOKOVIC

Fitness Game Changer:

Devotion to Longevity

He’s been around this long for a reason. Djokovic, 37, eliminated gluten and dairy from his diet, started practising mindfulness techniques like conscious breathing and visualisation, and even brought a hyperbaric chamber to the 2019 US Open.

Cameron Spencer//Getty Images

BEN SHELTON

Fitness Game Changer:

Explosive Strength Moves

Known for his consistently fast serves, Shelton, 22, relies on single-leg training, using dumbbells to do lateral lunges, step-ups, and even Bulgarian split squats. He focuses on exploding upward on every rep so he’s ready to attack the ball on each serve.

Darrian Traynor//Getty Images

FRANCES TIAFOE

Fitness Game Changer:

Overcoming Isometrics

Tiafoe spent last off-season doing overcoming isometrics: exercises that force the 27-year-old to hold a position against a load he can’t move. This aids in boosting power and strength and can improve joint health.

Ready to build muscle, burn fat and come out the other side looking, feeling and performing better? Click here to get 14 days of free access to the plan via the Men’s Health app.

Andrew Gutman, NASM-CPT is a journalist with a decade of experience covering fitness and nutrition. His work has been published in Men’s Health, Men’s Journal, Muscle & Fitness, and Gear Patrol. Outside of writing, Andrew trains in Brazilian Jiu-Jitsu, helps coach his gym’s kickboxing team, and enjoys reading and cooking.