It’s one of the most complex, contentious questions in sports: Who are the fittest athletes in the world? Every sport makes different demands and physiques are carved and cut and chiseled in distinct ways, but success at each often hinges on conditioning. What happens when you level the playing field and compare disparate sports?

With the help of a panel of trainers, exercise physiologists and performance experts, athletes were selected based on their performances over the last 12 months; demands and risks of their respective sports; durability; training regimens; and other physical criteria including power, speed, strength, agility, endurance, flexibility and more.​

Read more about the selection process here, and count down to see the fittest male and female athletes in the world right now.

Meet the Experts

Dr. Michael Joyner

Human performance expert, Mayo Clinic

David Hesse

Vice president for performance, IMG Academy

Dr. Christopher Lundstrom

Exercise physiologist and coach of elite distance runners

Roy Holmes

EXOS performance manager, CSCS

Sue Falsone

Physical therapist, athletic trainer and author

Click below to navigate to the complete list of men and women.

MEN

WOMEN

25

Brooks Koepka

PGA Tour

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If you don’t think golfers are athletes, you haven’t seen 28-year-old Brooks Koepka in the gym. The world’s top golfer and 2018 U.S. Open and PGA Championship winner, Koepka gets his strapping 6-foot, 186-pound frame and bulging biceps from intense lifting sessions and dynamic workouts focused on explosiveness and mobility, often with Florida-based trainer Joey Diovisalvi. ​

Erick W. Rasco

24

Geraint Thomas

Cycling

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In July 2018, 32-year-old Geraint Thomas became only the third Brit to win the Tour de France, cycling’s famed 23-day race that is the ultimate test of extreme endurance and the ability to push past pain and suffering. Before ruling the road, Thomas captured two Olympic gold medals in track cycling in 2008 and ’12.

Justin Setterfield/Getty Images

23

Jim Walmsley

Ultrarunner

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What would it take for you to run more than 4,000 miles in a year? It’s standard for trail- and ultra-runner Jim Walmsley, who surpassed that mark on Strava in 2018 in his training for several top finishes, including a course-record 14 hours, 30 minutes at the Western States 100-Mile Endurance Run (the Super Bowl of ultra-running) in June. Walmsley customizes his diet in order to fuel his body for the ultra distances and training for various terrains and trails.

22

Caeleb Dressel

Swimming

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At age 22 and more than a year out from the Tokyo 2020 Summer Olympics, Caeleb Dressel is already making waves. Standing at 6’3” and 190 pounds, the American sprint specialist dominated the 2018 NCAA Championships. He then went pro in 2018, signing with Speedo and breaking records at the ’18 Fina World Championships. In addition to training for missile-like, explosive power off the blocks, Dressel has mastered the art of building strength without adding too much muscle mass or bulk.​

Fred Lee/Getty Images

21

Eliud Kipchoge

Marathon

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The 34-year-old Kenyan cemented his place as the greatest marathoner of all time in 2018, crushing the world record by one minute and 18 seconds with his 2:01:39 finish at the Berlin Marathon. While the feat further proved his dominance in the 26.2-mile distance, Kipchoge isn’t done yet—he plans to continue constructing his 5’6”, 115-pound body into an even finer-tuned marathon machine.

Maja Hitij/Bongarts/Getty Images

20

Connor McDavid

Edmonton Oilers

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While the NHL is full of incredible athletes, it’s speed that sets Edmonton Oilers center Connor McDavid apart from others in the league. The 21-year-old has won two consecutive fastest skater titles at the NHL All-Star Game SuperSkills Competition. And his commitment to honing his agility and acceleration on the ice, combined with his masterly stick-handling and puck control, is paying off: in December 2018 alone, McDavid put up eight goals and 24 points in 13 games.​

Ronald C. Modra/NHL/Getty Images

19

Hamish Bond

Rowing

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A two-time Olympic gold medalist in the coxless pair at London 2012 and Rio ’16 and world champion for six consecutive years, New Zealand’s Hamish Bond dominated rowing for nearly a decade. But the 32-year-old is now looking to make his mark in a second sport, switching to road cycling with an eye on Tokyo 2020—clear evidence of his peak conditioning.​

Photo by Justin Setterfield/Getty Images

18

Patrick Mahomes

Kansas City Chiefs

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During his breakout 2018 season, Kansas City Chiefs QB Patrick Mahomes has demonstrated his superhuman abilities with seemingly impossible throws and sneaky escapes from defenders. His arm strength and athleticism could translate to several sports—in fact, before becoming an NFL star, Mahomes was a top baseball prospect and didn’t play football full-time until he was a sophomore in college.​

David E. Klutho

17

Giancarlo Stanton

New York Yankees

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While he may not have had an MVP-caliber season in his first year with the New York Yankees, Giancarlo Stanton hit .266 with 38 homeruns and 100 RBI and still ranks as one of the fittest, most powerful hitters in Major League Baseball. During the offseason, the 6’6” outfielder is known for intense (and insane) workouts, from traditional lifting sessions to unconventional physical challenges.​

Winslow Townson

16

Kjeld Nuis

Speedskating

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At the 2018 Winter Olympics in Pyeongchang, Dutch speedskater Kjeld Nuis won gold medals in the 1500- and 1000-meter events, after many world championships since his first in ’14. Besides focusing on form and technique, Nuis adds cycling, resistance training, plyometric exercises and Olympic lifting techniques into his vigorous workouts. ​

Joosep Martinson/International Skating Union (ISU)/ISU via Getty Images

15

Tommy Caldwell

Rock climbing

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Tommy Caldwell is known for his historic free-climb ascent of the El Capitan’s Dawn Wall in Yosemite National Park and is considered one of the world’s best free climbers, along with good friend Alex Honnold. To complete his impressive feats, 40-year-old Caldwell uses various techniques to build the aerobic conditioning and muscular strength needed to scale small edges of rocks and boulders. From mountain running to backcountry skiing, the workouts are always adventurous.

14

Patrick Lange

Triathlon

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In October 2018, Germany’s Patrick Lange became the first-ever athlete to break eight hours at the IROMAN World Championships in Kona, Hawaii, setting a new course record of 7:52:39 en route to his second straight title. Remarkably, the 32-year-old didn’t do his first full IRONMAN race until 2016 and before becoming a professional triathlete, Lange worked as a licensed physiotherapist, so he puts a lot of his training focus on recovery.

Donald Miralle

13

Russell Westbrook

Oklahoma City Thunder

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Oklahoma City’s star continues to make triple-double history with every game he plays, chasing Magic Johnson (138) and Oscar Robertson (181) for the most in NBA history. At 6’3” with a 7-foot wingspan, Westbrook incorporates sprints, weight lifting sessions and resistance training into his regimen—though most of his workout details are kept under wraps.

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12

Luka Modrić

Real Madrid

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In Croatia’s run to the World Cup final in 2018, team captain Luka Modrić recorded a distance of 39.1 miles ran but showed little signs of fatigue, a marker of his stamina and tireless ability to cover the pitch. The winner of several major awards in 2018—including the FIFA World Cup Golden Ball, UEFA Men's Player of the Year Award, the Best FIFA Men's Player and the Ballon d'Or—the Real Madrid midfielder is known to be obsessed with staying in prime physical shape. ​

Juan Manuel Serrano Arce/Getty Images

11

Aaron Donald

Los Angeles Rams

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Los Angeles Rams defensive tackle Aaron Donald is in line to win a second-straight NFL Defensive Player of the Year award, thanks to his Hulk-like 6’0”, 284-pound build, menacing pass-rushing tactics and punishing combo of explosive power, agility and brute strength. Donald finished 2018 with 20.5 sacks and forced four fumbles in his fifth season in the league.​

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10

Canelo Álvarez

Boxing

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It was an up-and-down year for Canelo Álvarez, after a rematch of a controversial draw with Gennady Golovkin was canceled following Álvarez's positive test for a banned substance. But following a six-month suspension, the Mexican boxer ultimately came out on top, returning in September to defeat GGG in a majority decision to win the unified middleweight title. Then three months later, Álvarez moved up one weight class to claim the super middleweight world title with a third-round knockout of Rocky Fielding. A mix of elite conditioning, stamina and power punches makes Alvarez one of the world’s best in the ring.

Erick W. Rasco

9

Conor McGregor

UFC, boxing

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Though he wasn’t victorious against Khabib Nurmagomedov in his much-anticipated return to the octagon, Conor McGregor’s ability to swing from UFC to boxing and then back again is a testament to his superior fitness. A multi-weight champion in UFC, the 30-year-old from Ireland packs precision and punishing power into his signature punch.​

John W. McDonough

8

Jordan Burroughs

Wrestling

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After leaving the Rio 2016 Olympics without any hardware, 30-year-old American Jordan Burroughs is still chasing Olympic gold—and U.S. wrestling history. Burroughs finished with a bronze medal at World Championships in 2018, but he’s still working towards Tokyo 2020, focusing on building explosiveness, not bulk, on his brawny, 5’7” frame.

Charlie Neibergall/AP/REX/Shutterstock/Getty Images

7

LeBron James

Los Angeles Lakers

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At age 34 and in his 16th NBA season, LeBron James knows how to sculpt, shape and strengthen his 6’8”, 250-pound beastly body for the rigor of the NBA season. From plyometrics to Bodyblade exercises, to a team of coaches, trainers, personal chefs and masseuses that help him prepare, James spends a lot of time—and money—on his physical fitness, but the attention to detail continues to pay off as his storied career carries on. ​

John W. McDonough

6

Mat Fraser

CrossFit

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It was a record year for 29-year-old Mat Fraser, who took home his third consecutive CrossFit Games title in dominating fashion with a record 220-point separation between the American and the rest of the field. From three-plus hour weightlifting workouts to metabolic conditioning and lengthy recovery sessions, Fraser’s full-time job is training to keep his 5’7”, 190-pound physique in prime condition—and he’s damn good at it.

Courtesy of CrossFit, Inc.

5

Kevin Mayer

Decathlon

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On the same day the record books were rewritten in the marathon in 2018, France’s Kevin Mayer broke the decathlon world record, earning 9,126 points over the 10 events, 81 points higher than the previous mark set by Ashton Eaton. An Olympic silver medalist in 2016, 26-year-old Mayer’s remarkable success in the grueling, diverse event speaks to his exceptional conditioning in all aspects of fitness.

ANDREJ ISAKOVIC/AFP/Getty Images

4

Novak Djokovic

ATP tennis

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After missing part of 2017 due to an elbow injury, Serbia’s Novak Djokovic stormed back to his best form in ’18, winning back-to-back Grand Slam titles at Wimbledon and the U.S. Open and reclaiming the World No. 1 spot for the first time since ’16. Lean, long-lasting and limber, the 31-year-old’s resurgence is due in part to his commitment to injury rehabilitation, conditioning, diet and mental health.

DON EMMERT/AFP/Getty Images

3

Giannis Antetokounmpo

Milwaukee Bucks

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Have you seen Giannis Antetokounmpo lately? Last offseason, the 24-year-old made it clear that he was taking his game to the next level, bulking up his already-intimidating 6'11", 242-pound frame (and 7'3" wingspan) for his sixth season in the league. Antetokounmpo has continued to transform his body—and deliver on the court—over the course of his career, remaining committed to weightlifting sessions and adding boxing into his regimen. They don’t call him the “Greek Freak” for nothing.

Vaughn Ridley/Getty Images

2

Cristiano Ronaldo

Juventus

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At the age of 33, Portuguese footballer Cristiano Ronaldo is a physical specimen, sporting a perfectly chiseled six-pack, sinewy leg muscles and bulging biceps, plus a self-proclaimed “biological age of 23” that keeps him performing at a top level on the pitch. The Juventus star is known for his obsession with fitness and his training sessions incorporate every aspect of physical conditioning.​

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1

Saquon Barkley

New York Giants

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If there was a rookie milestone to clear in 2018, you could count on Barkley to hurdle it. With a menacing mastery of breakout speed, punishing power and acrobatic moves—and those massively muscular quads—the 21-year-old workhorse shattered records, becoming only the third first-year back to eclipse 2,000 yards from scrimmage. ​

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Michael J. LeBrecht II

25

Claressa Shields

Boxing

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American Claressa Shields has no problem calling herself “the greatest woman of all time,” and rightfully so, as the 23-year-old from Flint, Mich., is a two-time Olympic gold medalist and unified world champion in two weight classes, capturing the WBC female super middleweight title in November 2018 to add to her WBA and IBF female middleweight titles. In between her own rigorous training, Shields also serves as a training partner to UFC fighter Cris Cyborg.​

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24

Julie Ertz

USWNT, Chicago Red Stars

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Chicago Red Stars and USWNT midfielder Julie Ertz (née Johnston) has an extraordinary combination of toughness, agility and stamina—plus first-rate ball-winning skills—that make her an impactful player on the field. When she’s not lacing up her sneakers for long runs, Ertz hits the gym with her husband, Eagles tight end Zach, for intense workouts that target core strength and balance.

Jeremy Reper/ISI/REX/Shutterstock

23

Jessie Diggins

Cross-country skiing

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While her sport mainly demands endurance, Minnesota native Jessie Diggins must also go all-out on power and speed during a race—remember that insane finish in Pyeongchang? The 2018 Olympic gold medalist uses plyometrics, interval training, roller skiing and slacklining to develop a cardio base, strong core, explosiveness and balance. ​

Bob Martin

22

Caroline Wozniacki

WTA tennis

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A former World No. 1 and the 2018 Australian Open champion, Caroline Wozniacki continues to demonstrate her superior fitness, even with her recent rheumatoid arthritis diagnosis. To help with the condition’s symptoms, the 28-year-old expects to add more mobility exercises to her already diverse regimen, which includes traditional speed training, boxing, yoga and more.​

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21

Maggie Steffens

U.S. water polo

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The list of accomplishments for 25-year-old Maggie Steffens is lengthy: two Olympic gold medals, two world championships, two Pan-Am Games titles and two World Cups, plus three NCAA titles at Stanford. Her trophy case is filled thanks in part to her approach to training her 5’8”, 165-pound body. Steffens will go from the CrossFit gym, to workouts on the beach, to laps in the pool—sometimes all in one day.​

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20

Lindsey Vonn

Alpine skiing

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While she announced that the 2018-19 season will be her last before retirement, four-time World Cup champion Lindsey Vonn isn’t letting the end of her career—or another injury—stop her. The 34-year-old dominates on the slopes and in the gym, with beastly workouts consisting of everything from battle ropes to Olympic lifts and more.​

Thomas Lovelock

19

Sasha DiGiulian

U.S. rock climbing

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Not even a fractured leg could stop 26-year-old Sasha DiGiulian from scaling walls and killing it in the gym. Standing at 5’2”, DiGiulian focuses on her strength-to-bodyweight ratio, finger strength and coordination through various dynamic movements and lifting exercises. After becoming the first North American woman to climb the grade 9a (5.14d), which is known as one of the hardest climbs achieved by a female, DiGiulian is aiming for ascents on every continent.​

Andy Mann/Red Bull Content Pool

18

Mikaela Shiffrin

Alpine skiing

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Just 23, Mikaela Shiffrin has already rewritten the record books in 2019, matching her personal best winning streak in slalom by capturing her seventh consecutive World Cup victory in the discipline. She’s won 12 of the last 13 and 28 of the last 34 World Cup slaloms she competed in, but that type of dominance doesn’t come without hard work. The 5’7” Shiffrin spends a lot of time in the “pain cave,” running sprints, flipping tires and building strength for the slopes.​

Bob Martin

17

Kaillie Humphries

Bobsledding

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Though she’s taking time off from competition, Canadian bobsledder Kaillie Humphries isn’t halting her intense regimen as she prepares for the 2022 Olympics. The three-time Olympic medalist dedicates three to five hours a day to a combination of sprinting and weight lifting, all designed for optimal performance during those fleeting few minutes on the bobsleigh track.

Clive Mason/Getty Images

16

Hilary Knight

U.S. ice hockey

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For a game as physical and fast as ice hockey, Hilary Knight needs to be both powerful and dynamic, which is why she emphasizes core strengthening exercises, medicine ball drills and plyometrics in her off-ice workouts. After taking silver at both the 2010 and ’14 Olympics, Knight helped the U.S. team capture gold in Pyeongchang in ’18.​

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15

Emily Regan

Rowing

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A three-time gold medalist at the World Rowing Championships and Olympic gold medalist in the women's eight in 2016, Buffalo native Emily Regan has surged in the sport since first competing on an international level in ’10. Regan, along with the rest of her team, is eyeing Tokyo 2020 after capturing another world title in ’18.​

Gian Ehrenzeller/Keystone/AP Images

14

Mary Keitany

Marathon

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The world record holder in a women-only marathon with a 2017 London Marathon time of 2:17:01, 36-year-old Kenyan Mary Keitany has dominated distance running for nearly a decade. In 2018, she added a fourth New York Marathon title to her résumé, recording the second-fastest time in the race’s history and just 17 seconds off the course record.​

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13

Caster Semenya

Track and field

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In 2018 in the 800 meters, Caster Semenya amassed a 9-0 record and ran the fourth-, sixth- and eighth-fastest times in history, while also putting up impressive times in the 1,500 meters. The South African runner is consistently dominant, but because of her hyperandrogenism, she also stirs up controversy. Semenya was left off the 2018 IAAF Athlete of the Year short list; she is now challenging the governing body on their new regulations for athletes with the condition.

SAEED KHAN/AFP/Getty Images

12

Courtney Dauwalter

Ultrarunning

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Colorado native and full-time science teacher Courtney Dauwalter specializes in extreme endurance events, the ultimate test of stamina, strength and spirit. In 2017, Dauwalter won the Moab 240 outright, finishing the 238-mile race in 58 hours, an incredible 10 hours ahead of the next competitor, male or female. ​

Joe Amon/The Denver Post via Getty Images

11

Breanna Stewart

Seattle Storm

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After losing more games in her first two WNBA seasons than she had in her life, Breanna Stewart reawakened in 2018, posting career highs in points, steals (1.4 per game) and shooting percentage (52.9), winning league MVP and leading the Storm to the WNBA championship. Stewart’s resurgence is a product of a diet overhaul and amped-up workout routine, featuring Pilates, yoga, weight lifting, saunas and more.​

Stephen Gosling/NBAE via Getty Images

10

Serena Williams

WTA tennis

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After a 14-month maternity leave and pregnancy complications that left her bedridden for six weeks after giving birth, 23-time Grand Slam champ Serena Williams returned to the WTA tour in 2018 with two runner-up finishes in three major appearances. One could argue that the 37-year-old isn’t at her peak conditioning level, but she’s no doubt a favorite to win yet another major title during the 2019 season.

Erick W. Rasco

9

Emma Coburn

Track and field, steeplechase

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Despite losing her American record to Courtney Frerichs in 2018, Coburn beat her younger compatriot three times and continues to be the face of American steeplechase, winning seven national titles since ’11. In her training for a middle distance event with one water jump and four barriers per lap, Coburn logs miles and completes a host of core and mobility exercises using resistance bands.​

Charlie Neibergall/AP/REX/Shutterstock/Getty Images

8

Daniela Ryf

Triathlon

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In October 2018, 31-year-old Daniela Ryf captured her fourth consecutive IRONMAN World Championship in Kona, Hawaii, even after being stung (twice!) by a jellyfish in the first moments of the 2.4-mile swim leg of the race. The Swiss triathlete shattered her 2016 overall course record by more than 20 minutes and shows no signs of slowing down in ’19.​

Donald Miralle

7

Amanda Nunes

UFC

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After ending Cris Cyborg’s unbeaten streak at UFC 232 with a stunning 51-second knockout to become the first female fighter to win UFC titles in multiple weight classes, Amanda Nunes confidently declared herself as the sport’s greatest fighter. While some may debate that claim, there’s no denying the dominance of the 30-year-old Brazilian, who trains only with men and delivers a lethal combination of powerful striking and underrated grappling skills.​

Christian Petersen/Zuffa LLC/Zuffa LLC via Getty Images

6

Katie Ledecky

Swimming

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The world’s most dominant female swimmer had a quiet 2018 season by her unbelievably high expectations, earning three golds, a silver and a bronze medal at the Pan Pacific Championships and becoming one of just three women to set an individual long course world record on the year. In addition to a handful of world records, Ledecky has five Olympic gold medals and 14 world championship gold medals, the most in history for a female swimmer, and she’s already training to extend her reign at the Tokyo 2020 Games.

AP Photo/Nicola Shannon

5

Gwen Jorgensen

Triathlon, marathon

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After becoming the first American to win a gold medal in the Olympic triathlon, Gwen Jorgensen decided to leave the sport—and her place as one of the world’s top triathletes—to pursue a new one: the marathon. Following the birth of her child in 2017, 32-year-old Jorgensen declared that her new goal was to win a gold medal in the Olympic marathon in ’20, and so far, she's seen positive results in the 26.2 distance.

Charlie Neibergall/AP/REX/Shutterstock

4

Dina Asher-Smith

Track and field

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Just 23 years old, British sprinter Dina Asher-Smith finished 2018 as the European champion and world leader in the 100-meter, 200-meter and 4x100-meter races. In order to increase her power and explosiveness on the track, Asher-Smith doesn’t lift heavy weights, instead sticking to core strengthening and single-leg stability work—and plenty of grueling track workouts, of course. ​

Alexander Hassenstein/Getty Images

3

Tia-Clair Toomey

CrossFit

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Hailing from Australia, 25-year-old Tia-Clair Toomey successfully defended her CrossFit Games title of “Fittest on Woman on Earth” in 2018 and she’s the favorite again in ’19. An Olympic weightlifter that completed at Rio 2016, the 5’2”, 128-pound Toomey also won a gold medal in the women's 58 kg event at the 2018 Commonwealth Games. Toomey’s enviable six pack is a mark of her sheer strength, flexibility and power.​

AP Photo/Manish Swarup

2

Caterine Ibarguen

Track and field

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Named IAAF’s Female Athlete of the Year in 2018, 34-year-old Colombian Caterine Ibarguen posted an unbeaten season, winning the IAAF Diamond League and Continental Cup titles in triple jump and long jump. Also an Olympic gold medalist from Rio, Ibarguen is now working towards Tokyo 2020 with a mix of sprinting sessions, technical training and weightlifting.

Lukas Schulze/Getty Images for IAAF

1

Simone Biles

Gymnastics

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She may only stand at 4’9” but the world’s most decorated gymnast towers over the competition. After time away in 2017, the 21-year-old Biles returned to rule the sport again in ’18 with an unmatched mix of muscle and mettle. At the world championships in Doha, Qatar, in November, she set the record for career world titles among men and women, with 14, including four more gold medals—all while suffering from a painful kidney stone. An all-around champion, indeed. ​

Ulrik Pedersen/CSM/REX/Shutterstock/Getty Images