A Swimmer In The Blue Water Of The Pacific Ocean Near Kona, Hawaii.

Olympic 10K Marathon Swim vs. Marathon vs. 10K Run

BY Joshua Lawton

How the Olympic 10K Marathon Swim stacks up against Marathon and 10K running as interest grows in open water swimming through pop culture.

As endurance sports seem to get longer and more challenging and as more awareness and interest grow in the various sport types, open water swimming has begun to show up on more people’s radars. Recent films, including “Nyad” and “Young Woman and the Sea,” have helped stoke a renewed interest in open water swimming. Highlighting the challenges and accomplishments of women in the early days of the sport. 

Open water was the forum for all swimming competitions in the first two modern Olympiads, 1896 and 1900. In the 1970s, triathlons were born in open water for the swim segment, and the biggest races today continue to use open water from lakes to rivers to oceans for 3.8 kilometers. In 2008, the Olympic committee debuted the Olympic Marathon Swim at the games in Beijing, bringing open water competition back into the broader world’s stage. The FINA World Aquatics Championships have featured marathon swim events since 1992. Seeing “Marathon Swim” in the competition list spurred a personal interest to learn more in the build-up to selection committee announcements.

The race format of the Olympic 10K Marathon Swim (6.21 miles) is pretty simple. It’s a single mass-start, with no preliminary rounds. Competitors use freestyle swimming, and there are no stroke regulations. To get a better understanding of open water competition, I talked with Brian Johns, Head of Coaching Science with goggles company FORM. He believes many view the 10K Marathon as an open water swimmers’ cultural reference point, much like a Marathon time for runners. This rising interest from swimmers is leading to more popularity of shorter — and longer distances like channel crossings — in open water adjacent to the 10K, similar to the running world where participants build up from a shorter distance and aim for the bigger challenge.

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Comparing the Names, Duration and Distances

With marathon in the name of the event, how does the Olympic Marathon Swim match up to one of the most popular running distances, the 26.2-mile Marathon? Or what about the equivalent 10K Run on the track? 

Let’s start by comparing the named versions of the Marathon by duration. The faster finish times for the Olympic Marathon Swim will be in the 1:48-2:00 range. The 2021 (the games were delayed by a year due to the global pandemic) men’s gold medal winner, Germany’s Florian Wellbrock, finished with a time of 1:48:33, while the women’s gold was won by Brazilian Ana Marcela Cunha, with a time of 1:59:30. Not far off the world record Marathon running times, and faster than Olympic Marathon run times. 

The recognized run Marathon world record was set in October 2023 by Kenyan Kelvin Kiptum at 2:00:35, nearly breaking the two-hour barrier that has been chased by the world’s best in the last few years. Tragically, Kiptum died in a vehicle accident shortly after setting the record. The women’s world record for the Marathon run is 2:11:53 by Tigst Assefa of Ethiopia, set in September of 2023 — the first woman to break the 2:12 barrier. 

The Olympic Marathon records are slightly longer than the times on the major Marathon courses, in part due to the course variations from host cities. The women’s Olympic record is 2:23:07, set by Erba Tiki Galana at the 2012 London games, and the men’s is 2:06:32, set by Samuel Wanjiru in Beijing in 2008.  

Now that we’ve compared the swim duration to a Marathon run, let’s look at the same distance covered by swimmers and runners. Remember, the swim takes nearly two hours to cover the 10 kilometers. The world’s best to run on terra that far takes about half an hour. According to World Athletics, the women’s 10K world record time is 30:01, held by Agnes Jebet Tirop of Kenya in the women’s only race and 28:46 by Agnes Jebet Ngetich of Kenya in the mixed gender race. Rhonex Kipruto of Kenya holds the men’s record with a scorching time of 26:24. The Olympic record times — set on the track as there isn’t a road race of that length — are 29:17:45 by Ethiopia’s Almaz Ayana for women and 27:01:17 by Ethiopia’s Kenenisa Bekele on the men’s side. As you can imagine, swimming has many factors to consider when covering the same distance. Drag, currents, water temperature and more.

The Marathon Swim also has unique energy demands and course structure for racing, leading to complex nutritional demands and tactics. 

Olympic Marathon Swim Versus Marathon Run versus 10k Run Infographic on distance and duration

What It Takes to Race the 10K Marathon Swim

Johns points out that some of the best swimmers in the 1500m and 400m are also becoming some of the best open-water competitors. You can think of the 10K Marathon Swim as somewhat like a one-day bike race. Competitors will see dynamic action in a pack with drafting for some time before one or more attacks off the front to get separation, or it can come down to a drag race in the final kilometer kick for the finish.

The structure of the course can dictate much of the tactical approach to a race. If the course is a single loop, nutrition will be more challenging than a looped course. On a looped course, swimmers can get nutrition handed to them from crew, but they cannot touch anything other than the container for the food or drink. If a competitor were to touch a boat or dock, they would be disqualified. In events with multiple course loops, nutrition strategy can resemble aspects of an F1 race, forcing racers to time calories and caffeine with dynamic efforts and intense finishes. 

So, what does training for the Marathon Swim look like? Johns says an elite marathon swimmer will spend 25-30 hours in the water, mainly focusing on daily doubles five days a week, consisting of 7,000-10,000 meters per workout. This is compared to marathon runners, who spend 10-12 hours a week and run approximately 120 miles weekly. As you can imagine, there is much less impact on the body powering through water. 

According to Johns, many rely on stroke or heart rate to measure swim training, but data recording wasn’t monitored much until recently due to limitations on devices by governing bodies of open water competition. Rules prevent data from being broadcast or shown during competition — devices like FORM goggles are prohibited. However, in early 2023, swimmers were allowed to record data during a race from a short list of approved wearables by the World Aquatics Group, formerly FINA. This has opened the sport to more data collection outside the pace or race clock to get a better measurement of the work an athlete must produce in training and racing. 

As longer endurance events gain the attention of athletes looking for unique and colossal challenges, open water swimming could grow to a broader audience with the success of athletes leveraging social media and cultural artifacts like the movies mentioned above. Keep these pages bookmarked to watch the Marathon Swim, the Marathon or the 10K at the 2024 Summer Games. 

If you’re looking to jump into the open water for longer swims, there are several training plans from great swim coaches in the TrainingPeaks marketplace. Or if the water isn’t your thing and you want to improve your Marathon or 10K time, we have plans for you, too.

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About Joshua Lawton

Josh is a Content Strategist for TrainingPeaks, producing the TrainingPeaks CoachCast and other multimedia content for athletes and coaches. He’s also a long-distance adventure bikepacker and believes the trail 50K is the perfect ultrarunning distance. Feel free to reach out with endurance journies to highlight in TrainingPeaks channels.  jlawton@trainingpeaks.com.

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