When Léon Marchand became the greatest swimmer in French history this week with an unprecedented double run of two gold medals in less than two hours on Wednesday night, Marchand mania took over the nation.

Commentators announced that the shy, smiling 22-year-old, known as “half man, half dolphin” for his powerful underwater push-offs, had “restored national pride”.

The cheering frenzy was not confined to 17,000 spectators raising the roof of the swimming arena – even though coaches said they had never heard anything like it. Applause and screams also erupted on streets from Paris to Toulouse, even on public transport. More embarrassingly for France, other Olympics competitions – including table tennis, tennis and a fencing final – had to be briefly paused as the noise of French spectators in the stands cheering Marchand while following on their phones interrupted proceedings.

Related: Léon Marchand seals historic double with gold in 200m butterfly and breaststroke

Marchand, who took his gold tally for a remarkable Games to four on Friday night in the men’s 200m individual medley, is adored not only for his technique in the pool but for his personal story. Born in the south-western city of Toulouse, he comes from a family of Olympic swimmers – his mother, father and uncle – who initially didn’t want him to follow their footsteps because they knew the stress it entailed.

Indeed Marchand, a computer programming student who loves video games and Japanese manga comics, and whose hobby is aviation as he hopes to gain a pilot’s licence, has described himself as reserved and not naturally at ease in the spotlight. He has been open about the emotional challenges of elite sport and says mental wellbeing matters as much as technique for competitive swimming. His pre-race relaxation breathing techniques and a determination to smilingly enjoy the race are crucial, he has said. “You have to take pleasure in it,” he told Brut Media two years ago – suggesting this wasn’t a given amid the pressure on the starting blocks.

When Marchand was 19 he left France for the US to study computing at Arizona State University and train with Bob Bowman, the coach who built the career of the American Michael Phelps – the most decorated Olympic swimmer with 28 medals, including 23 golds.

Bowman refuses to compare the two swimmers, whom he considers very different. Bowman never allowed Phelps to attempt two golds in two hours and tried to persuade Marchand against competing in two key finals on the same night in Paris, but Marchand insisted. “He’s polite, calm, has great humility, is an excellent student and a swimmer with a rare work ethic,” Bowman previously told L’Équipe. “What I like is that he viscerally loves swimming,” Bowman added, saying Marchand has had good technical training as well as his good genes.

Marchand’s mother, Céline Bonnet, now a flight attendant, was a professional swimmer who began breaking French records at 15 and swam at the Barcelona Olympics in 1992. His father, Xavier Marchand, now a TV journalist for the French public broadcaster, competed in two Olympics. “My parents never pushed me,” Marchand has said, adding that they initially tried to dissuade him, knowing the sacrifices it entailed. As a young child, he found the pool a bit chilly as he waited shivering at the edge after winning races. He briefly tried judo and rugby, but always came back to the pool. His parents advised him to focus on the individual medley, like they had, because a range of strokes was more interesting.

As a teenager, Marchand trained with the Dolphins team at the TOEC club in Toulouse. He swam in a pool named after Alfred Nakache, who swam for France in the 1936 Olympics, before he was deported to Auschwitz where his wife and two-year-old daughter died. He survived and went on to compete at the 1948 Games. Documentary footage of Marchand as a young teenage hopeful in Toulouse saw him studying hard at high school for his baccalaureate, which he passed with excellent grades, telling the cameras he needed academic work “as a back-up option” in case swimming didn’t work out.

Marchand has been open about how when he was about 18 and performing well in French competitions, the pressure to constantly succeed and the fear of failure almost became too much. Confinement during Covid ironically helped him as it allowed him to spend down time with his family and live, as he says “like a normal human being”, having the occasional lie-in and playing video games with his younger brother.

Marchand worked with Thomas Sammut, who trains elite athletes on their mental approach to sport. Through working on the psychological aspects of competing, he turned things around before his appearance at the Tokyo Olympics aged 19. “I now like to ask myself what would happen if I fail,” Marchand told Brut. “And I realise nothing will happen: my family will always be just as happy for me. So now I have no more fear of failure. I’m enjoying it.” He said of Sammut: “Sportspeople used to be scared to see that type of person because it could maybe show mental weakness, I was never afraid of that. I wanted to get better in my sport, but above all I wanted to keep smiling in my everyday life.”

Marchand’s massive support from the crowds in France could have brought renewed pressure. In his first breaststroke race, the crowd would fall silent at intervals then cheer each time he took a breath. But Marchand now thrives on it. As a coach, Bowman understands rowdy home crowds and passed on a tip that the Australian Ian Thorpe had once told him: not to see it negatively as pressure, but frame it positively as support.

Marchand told journalists after his double gold win that he was so grateful for the French support. “It’s crazy because the public is so present and I’ve really shared some incredible moments with the spectators,” he said.

Five other French Olympic stars

Victor Wembanyama, basketball

The 20-year-old basketball prodigy, known in France as “Wemby”, towers over rivals at 2.24m (7ft 4in). He is the driving force of the men’s basketball team, drawing huge crowds. Wembanyama, who was born outside Paris to parents who were competitive athletes, moved to the NBA last year, where he was considered the most promising young player since LeBron James entered the league almost 20 years before. After his debut for the San Antonio Spurs, Wembanyama was unanimously voted NBA Rookie of the year for 2024 – the first French player to take the award.

Cyréna Samba-Mayela, 100m hurdles

The 23-year-old sprinter and European champion in the 100m hurdles is France’s biggest hope in athletics. Born in Champigny-sur-Marne, east of Paris, she tried various sports from figure skating to judo before settling on athletics at 15. Samba-Mayela has been training in the US, but caught Covidthis year, affecting her training. Her Irish coach John Coghlan hailed her “physical and mental strength, her technique and her love for the sport”. He said at the start of the Games: “She can become one of the best in history.”

Antoine Dupont, rugby sevens

The Toulouse scrum-half, 27, pivoted to the fast-paced rugby sevens for the Olympics. He played a key role in France winning gold and he was seen as the best player on the pitch in the final, held aloft by cheering supporters in the Paris fanzone. “Competing for an Olympic gold medal is really motivating,” he said when he announced he would quit his comfort zone and move into high-intensity rugby sevens for the Games.

Félix Lebrun, table tennis

The 17-year-old from Montpelier is a household name in France credited, alongside his brother Alexis, 20, with creating so much excitement around the sport that French table tennis clubs have seen a rise in membership. They have a large following in China and drew huge crowds in the men’s singles in Paris, where Félix is aiming for a bronze medal. Both will play in the men’s team events next week.

Manon Apithy-Brunet, fencing

The 28-year-old from Lyon took gold in women’s sabre fencing after a final against her teammate Sara Balzer – the first all-French Olympics fencing final in almost 30 years. More than 8.6 million viewers tuned in for the dramatic last moments of the final on the French public broadcaster France 2. Apithy-Brunet is the first French women’s sabre fencer to take an Olympic gold. She is hoping for another medal with the women’s team, which competes this weekend. After the Rio 2016 Olympics, Apithy-Brunet joined the French gendarmerie through its scheme for elite athletes.