It’s the question the entire swimming world has been asking ever since Summer McIntosh made herself known on the world stage by qualifying for the COVID-delayed Tokyo Olympics at the age of 14. The Canadian swimmer finished fourth in the 400-meter freestyle there, but she won two gold medals a year later at the 2022 World Aquatics Championships (in the 200m butterfly and 400m individual medley), and the world knew Canada had a star in its ranks.Fast forward four years, and McIntosh is on track to become one of the sport’s biggest names ever. At 19, she is a three-time Olympic champion, eight-time world champion and two-time Commonwealth Games gold medallist. She also holds world records in the 200m butterfly, 200m individual medley (IM), 400m freestyle and 400m IM.So good is McIntosh that on Thursday at the Pan Pacific Championships — the biggest meet of the year for swimmers in the Americas and Oceania — she easily won the 400m IM in an event-record time of 4 minutes, 28.01 seconds … and was disappointed by it. It’s the 10th-best swim in the event’s history, and she now owns 10 of the 11 top times, but it was more than four seconds off her own record.“Overall just not happy with it,” she said after the race. “I should be capable of more based on my training and (I was) way far off my world record. So I need to reflect on what went wrong and see how I can improve.”That’s a scary thought for the field ahead of the 2028 Olympics in Los Angeles, where McIntosh is targeting gold medals in five events.“When you’re that good, that young, you’re gifted,” British former world champion swimmer Mark Foster said. He made the GB national team at the age of 15 and won his first Commonwealth Games medal at 16 but describes himself as “good” rather than great.“The greats are the ones that can either dominate a race for a long period of time, like Adam Ramsay-Peaty (the GB swimmer who won the 100m breaststroke at the 2016 and 2020 Olympics),” Foster said, “or they can float across a few different events, medal in all of them and win some of them.“She’ll (Summer) win 200-meter fly at the Olympics, but she’ll also win the 400-meter freestyle, maybe 800-meter freestyle, maybe 200-meter breaststroke. She’ll win the 200-meter medley, the 400-meter medley — she’s just that good.”How does she do it?John Atkinson has been high performance director and national coach of Swimming Canada since 2013 and has seen up close the talent and hard work that has gone into McIntosh’s incredible career so far. He told The Athletic that her “ability to train for all four strokes, focused on 200-meter and 400-meter events, having shown she is world-class in the 800 free and can race with speed in 100-meter events, is remarkable and only possible with talent coupled with an attention to detail that makes her a special athlete.”McIntosh’s mother, Jill Horstead, was also an Olympic swimmer who competed for Canada in the 200m butterfly at the Los Angeles Olympics in 1984, finishing ninth with a time of 2 minutes, 13.49 seconds.At the Canadian swimming trials last month, McIntosh swam the same event in 2:01.65, breaking the longest-standing world record in women’s swimming of 2:01.81, set by China’s Liu Zige in October 2009.Good genetics are just one factor in what makes McIntosh the swimming powerhouse she is.Height is not one of them. Standing at 5 feet 8 inches (173 cm), she is not among the tallest world-level female swimmers (though also not the shortest). What she does have, though, is a wingspan of 180cm, some seven centimeters longer than she is tall. “Having long arms compared to your body length does contribute,” said Foster, who names 23-time Olympic champion Michael Phelps as another swimmer who famously had an impressive wingspan (around 201cm, while his height was 193cm).A larger wingspan means a swimmer’s arms can reach further and gives them more pulling power through the water.Summer McIntosh’s wingspan — longer than she is tall — helps give her superior pulling power through the water. She owns world records in four events. (Alex Slitz / Getty Images)What’s more important than wingspan to making a swimmer fast, though, Atkinson said, is the “application of power in the stroke technique and having endurance to maintain this.”The power in McIntosh’s strokes comes in part from her very effective “catch” technique, which refers to the way a swimmer’s arm and hand are positioned once they enter the water and how well they “catch the water,” pushing it backward.“The more water you can hold and use, the more efficient you are,” said Foster, who compares a swimmer to a race car. “A race car on skinny tires is not going to get a lot of traction. A race car on thick tires: a lot of traction.”McIntosh’s catch features a high elbow and fingers pointing directly down toward the bottom of the pool, resulting in a strong grip on the water.It’s one of the things that two-time Olympic champion Rebecca Adlington notices about McIntosh’s technique: “She gets her hand and forearm into a strong position early, creating a bigger surface area to push against, rather than her hand slipping through the water,” Adlington told The Athletic. “It means she gets a lot from every stroke, which is part of why she looks so effortless.”Efficiency is one word that comes up consistently when talking to people about McIntosh and the way she moves through the water. What does that look like in the pool? When it comes to swimming, “Efficiency is essentially the reduction of drag,” said Justin Richardson, head senior coach at Swim Neptune and founder of Peak Performance Swimming.He points to McIntosh’s body line and body position as being among the most important aspects when it comes to her efficiency: “She always rides up high on the water, especially in butterfly and freestyle. Hips are always up high, legs are never sinking. She keeps her kick up high in the water by engaging her posterior chain, her head position is steady on the surface in freestyle, and her breath is low and quick in butterfly.“This ties into stroke efficiency and strength. Since she maintains such a great body line, she moves through the water more easily. She is also putting her body in a position that allows her to maximise her strength. Put these together, and you can see how she gets so much distance with each stroke while keeping her stroke count low and under control.”McIntosh’s body position is down to “a combination of core strength, body alignment, head position, kick and technique,” Adlington said. “She stays incredibly horizontal and streamlined, with her hips high, which reduces drag. She has this across most of her strokes, not just front crawl.”At 19, Summer McIntosh is already at the top of women’s swimming. She has won 11 gold medals across the Olympics and world championships. (Quinn Rooney / Getty Images)Foster compares swimmers to speed boats in the way they propel themselves up high in the water to help gain more speed. McIntosh, he said, “looks really light on the water; she sits really high.“That goes down to catching water because when we swim, we don’t just pull ourselves forwards, we lift ourselves out and forwards. All the resistance is in the water, not on top of it. So you pop your body up like a speedboat. The more on top of the water you are, the faster you are.”Another important piece of the puzzle is McIntosh’s engine. “She does not fall apart at the end of her races,” Richardson said. “Her technique does not decay or get worse when she is tired.“Pair that with her ability to hold body position and really grab the water, and she is able to hold a faster pace and more efficient stroke for longer than those she is racing.”Not only can she hold her pace, but she can increase it when she needs to: “She seems able to change gears incredibly well,” Adlington said. “She can settle into a pace and look completely controlled, but then has another level when she needs it.”While Foster stops short of thrusting the term “perfection” on McIntosh, he said that her technique comes about as close to it as possible:“Her stroke is near perfect. Add that to her power to weight, the efficiency that she has and all the things you can’t see on top of the water — body rotation, timing of the hands passing the hips. … She’s like a rowing boat. You watch a lot of rowers in the Olympics, and if they’re pulling a bit too fast, or they’re out of sync, they don’t go very well.“Whereas if it’s all in time and in tempo, you can really see the boat move forward at a rate. And her timing is as perfect as it can be.”— The Athletic’s Peter Baugh contributed to this report.