By Anna Malpas in Kharkiv, Jonathan Brown in Kyiv, Philippe Siuberski in Montpellier and Diane Falconer in Fukuoka

As synchronised swimmers, Maryna and Vladyslava Aleksiiva are used to having to smile no matter what.

The sunny sisters are one of Ukraine's best hopes of a gold medal at the Paris Olympics after winning a bronze in artistic swimming at the Tokyo Games three years ago.

But the trials the 22-year-old twins have been put through -- forced to flee their homes, surviving shelling and sleeping in bomb shelters -- have tested even their stoicism.

They have even had to jump out of the pool and "run to the basement in wet swimsuits" when the explosions got too close, Maryna told AFP.

Russian tanks were stopped in the suburbs of their hometown Kharkiv during the invasion almost two years ago, with the sisters having to leave their sparkly costumes behind when they were evacuated.

Regular bombardments have not stopped them from returning to Kharkiv to prepare for the Games, even if the windows of their training pool are still broken from the missile attacks the border city is often subjected to.

"Everything has been bombed: our pool, where we started training, our school, our city centre," added Maryna.

While the Ukrainian army eventually pushed the Russian troops back, Kharkiv is still vulnerable, only 30 kilometres (19 miles) from the border. Last week, 11 people were killed in the latest wave of Russian missile attacks on the city.

It is not exactly the ideal environment for elite swimmers to go for gold, especially when there is no generator to warm the water when the power fails, as it often did last year after the country's electricity grid took a pounding from the Russians.

Sleeping in bomb shelters 

AFP has been following the sisters on their turbulent path to Paris, an odyssey that has taken them from Kharkiv to Italy, France, Poland, Spain, Japan and back.

"When the war started, we did not know what to do," said Vladyslava, the shyer of the two, who often lets her twin Maryna finish her sentences.

"But then we understood our main goal could be to show courage all over the world in competitions."

"To show Ukraine is still alive," Maryna added. "We must show strength."

With the Russians threatening to take the city in the early days of the war, the sisters fled Kharkiv with the rest of Ukraine's artistic swimming team and trained in Italy for six months.

But they were determined to go back to Ukraine to be closer to their parents, training in Kyiv and "sleeping at night in the corridor of a bomb shelter" before returning to Kharkiv.

They have not left their home city -- the heart of Ukraine's artistic swimming scene -- since then, except for short trips abroad to compete.

Even if it is more dangerous, "it's much better to be together, (even) without electricity and music to train," Vladyslava told AFP during a break in the World Aquatics World Cup in France in May where they won the duet gold.

They visited Montpellier's historic centre to eat ice cream and post stories on Instagram to celebrate.

But even in those carefree moments when they joked about the joys of having electricity, the war was never far away.

"I called Mum yesterday, but it was an air raid alert and I was a little bit nervous," said Maryna at the time. "Mum and Dad said, 'Don't worry, we're fine.' So we tried to keep calm and concentrate on our competition."

When we caught up with the twins again in July at the World Aquatics Championships in Fukuoka, Japan, they struck an even more sombre note.

"It is hard to focus when your country is at war and you are away from family," Vladyslava admitted.

Friends killed 

"We have friends who are sportsmen who died on the battlefield defending our country... it is an awful time for us."

Yet back on their sofa in Kharkiv on a rare day off in November, they did not turn a hair when the air raid siren sounded, even though Maryna's apartment is on the top floor and more exposed to shelling.

The sirens go off "five or six times every day" she said. "At night also. It's normal."

Every morning they read the news to see if it's safe to train, only going to the bomb shelter when it's really dangerous.

Vladyslava lives next door with her husband, an IT specialist, which is handy because "we always swap clothes, handbags, jackets, shoes," said Maryna.

On their lazy Sunday morning off -- the one day they do not have to train at 6:30 am -- the sisters wore jeans and jumpers and light makeup in contrast to the heavy warpaint they put on for performances.

Relaxing on the couch, they put on an Edith Piaf record from their grandfather's vinyl collection, which also included The Beatles and Pink Floyd.

Lying on a table nearby was Maryna's bronze Olympic medal from Tokyo. Vladyslava took hers with her when they fled to Italy because it was "the most dear to me".

"I was sure that they would be stars," said their childhood trainer, Maryna Krykunova, a tall, elegant woman in a tweed coat, who first came across them when they were eight years old.

Even then they were tall and supple and naturally in sync for duets, she told AFP.

With girls who are not siblings, "we have to spend a lot of time making them similar", she said.

"With Maryna and Vlada, they are already twins so it's much better."

Unsurprisingly, twins and even triplets are not uncommon in artistic swimming.

New obstacle 

But what used to be an advantage for the sisters may not be a help after a controversial change last year to the way artistic swimming is judged, which has shifted the emphasis from artistic effect to more technical elements.

It is yet another obstacle for the twins as their team strives to qualify for the Paris Olympics, which start on July 26.

"Our coaches are unhappy with the change in the rules," Maryna said, which makes routines look "very unartistic and awkward".

"We must do everything possible so everything is perfect," said Vladyslava.

The last qualifying rounds are at the world championships in Qatar next month, with the team building up for the European Aquatics Championships in Belgrade in June, a dress rehearsal for the Games the following month.

"This is the most important time in our lives," said Vladyslava, adding that they were having to prepare in "unequal conditions" compared to their rivals.

Russia, which has traditionally dominated the sport, will not be competing at the Olympics after its teams were banned over the invasion.

But individual Russian athletes who have not taken a strongly pro-war stance will be able to compete as neutrals, the International Olympic Committee ruled.

Ukraine's foreign ministry condemned the decision, and the sisters have also spoken out, telling AFP in April that it was "maybe better to not allow a terrorist country that killed our sportsmen (to participate)."

But they have since softened their stance, fearing Ukraine could boycott the Games.

Vladyslava said it would be "stupid that they (the Russians) can go -- having killed people -- and we didn't do anything and we can't go."

"We've been training every day for seven hours and we have a goal... to show the courage of our country to the whole world," said Vladyslava.

A medal in Paris would be the ultimate riposte to their Russian competitors who messaged them in the first days of the invasion telling them, "Don't worry, we will save you... it's a safety operation."

"You're crazy," Maryna replied. "I invite you to Kharkiv and you will see how my home town is now... everything has been bombed."