What happens when you level the playing field and compare athletes of all shapes and sizes in disparate sports? Presenting SI’s 2021 Fittest 50 rankings.
Physical conditioning is ubiquitous among the elite, as all athletes’ bodies are built to meet the unique demands of each sport and withstand the rigors of the game. But what happens when you level the playing field and compare athletes of all shapes and sizes in disparate sports?
Each year Sports Illustrated accepts the challenge and ranks the best-conditioned athletes in the world, consulting trainers, exercise physiologists and performance experts with experience across the college, pro and Olympic levels of sports to evaluate athletes on the following criteria: performances over the last 12+ months (taking COVID-19 layoffs into consideration); demands and risks of their respective sports; durability; training regimens; and other physical benchmarks including power, speed, strength, agility, endurance, flexibility and more.
Count down to see the fittest athletes in the world right now.
Written by Jamie Lisanti, Karim Noorani and Chris Chavez
Meet the Experts
Maggie Steffens, Water Polo
A two-time Olympic gold medalist in water polo, 27-year-old and Team USA captain Maggie Steffens is looking to lead her squad to a third-straight title in Tokyo this summer. The 5′ 8″, 165-pound Steffens is dedicated to fitness, mixing underwater training and pool workouts with Olympic weightlifting techniques to build both endurance and power.
Sara Hall, Marathon
Since shifting her focus to the roads, marathoner Sara Hall has caught the racing bug. Last October, the 38-year-old mother of four cast aside any disappointment from missing the U.S. team for the Tokyo Olympics with a runner-up, 2:22:01 finish at the London Marathon. Just two months later, she became the second-fastest female U.S. marathoner in history with a 2:20:32 win at The Marathon Project.
Kyra Condie, Sport Climbing
Since undergoing major surgery to correct scoliosis at age 12, when doctors fused 10 vertebrae in her spine, 23-year-old Kyra Condie has embraced her condition and utilized it to hone her unique climbing style. A member of Team USA for the Tokyo Olympics, Condie found creative ways to continue her training at home during the pandemic, hanging from door frames and mixing in “off-the-wall” workouts with limited equipment to keep her rock-solid, 5′ 4″ frame in medal-winning shape.
Kendall Coyne Schofield, Hockey
In 2019, Kendall Coyne Schofield rewrote the history books by becoming the first woman to compete in the NHL All-Star skills competition, finishing seventh in the league’s fastest skater event with a time of 14.346 seconds. Since that groundbreaking moment, the six-time world champion and two-time Olympic medalist has continued to put her strength, speed and agility on display, no matter the setting. That include Coyne Schofield squatting her 6′ 6″, 301-pound NFL offensive lineman husband at home during the pandemic.
Sandi Morris, Track and Field
U.S. pole vaulter Sandi Morris is a two-time world championship silver medalist and a 2016 Olympic silver medalist—could this be the year that she makes the jump for gold? The 28-year-old is one of two women to clear 5 meters and she takes her training very seriously. When the pandemic hit, she and her dad built a regulation pole vault pit in his backyard at his Greenville, S.C., home. From box jumps to battle ropes and more, Morris incorporates a variety of exercises into her routine.
Aja Evans, Bobsled
All eyes may be on the Summer Olympians gearing up for Tokyo, but two-time Olympian and Sochi 2014 bronze-medalist bobsledder Aja Evans is here to remind you that the Winter Games in 2022 are right around the corner. A standout shot putter before making the transition to bobsled, the 32-year-old is an all-around athlete with a diverse training regimen that includes everything from weightlifting to boxing and more.
Simone Manuel, Swimming
In 2016, Simone Manuel made history by becoming the first Black female swimmer to win individual Olympic gold, tying for first place in the women’s 100-meter freestyle. America’s short-distance swimming speedster looks to add to her résumé this summer at the Tokyo Olympics. In comparison to her contemporaries Manuel places a special emphasis on weight training to improve her burst and speed in the water.
Caroline Marks, Surfing
Still only 19 years old, Caroline Marks is continuing her remarkable rise in surfing in 2021, winning the first World Surf Tour event of the season after a second-place finish on the 2019 tour and a spot on the U.S. Olympic team for Tokyo. The 5′ 5″, 127-pound Marks takes her training seriously, whether it is on a board in the water or in the gym with weights and resistance bands.
Diamond DeShields, Chicago Sky
Entering her fourth WNBA season, 26-year-old Diamond DeShields is already one of the best and quickest athletes in the sport. After being named a WNBA All-Star in 2019, the 6′ 1″ Chicago Sky guard dealt with injuries in the 2020 WNBA bubble, but her pure athleticism was still on display. Coming from a family of pro athletes, DeShields has fitness in her blood and she’s known to incorporate nonbasketball training, such as boxing, into her workout regimen.
Dalilah Muhammad, Track and Field
Serving as queen of the 400-meter hurdles since the 2016 Olympics in Rio, Dalilah Muhammad put her stamp on the event by winning the U.S. Championships in 2019 with an imperfect race in 52.20, then by lowering her own mark with a 52.16 at the world championships that fall. The 31-year-old Muhammad has spent the last year-plus training to defend her gold medal in Tokyo this summer, adding in more endurance workouts with shorter recovery times to boost her fitness level even further.
Adeline Gray, Wrestling
In her pursuit of Olympic gold, 30-year-old Adeline Gray decided to put her dream of motherhood on hold to focus on her preparation for the Tokyo Olympics this summer, following the one-year delay due to the pandemic. After suffering a shoulder injury after the Rio 2016 Games, the five-time world champion is determined to work her way back, combining physical exercises in the gym with mental training and recovery to prime her body for peak performance.
Courtney Dauwalter, Ultra Running
Colorado native Courtney Dauwalter is a master of completing near-impossible athletic feats. It’s still mind-blowing that last October, the 36-year-old Dauwalter covered 283.33 miles in 68 hours to win the U.S. Big Dog’s Backyard Ultra, which required runners to complete a 4.16667-mile loop every 60 minutes until there’s just one runner standing.
Tianna Bartoletta, Track and Field
Three-time Olympic gold medalist Tianna Bartoletta is looking to make her third U.S. Olympic team this summer. During the pandemic, the 35-year-old started teaching yoga online to athletes across the country while still refining her chiseled physique in preparation for the U.S. Olympic Trials. From sprinting and jumping to yoga sessions and weightlifting in the gym, Bartoletta is an all-around athlete.
Katie Ledecky, Swimming
Despite the postponement of the Olympics last year, Katie Ledecky has not stopped improving. The 24-year-old, who has been itching to compete since an illness limited her in the 2019 world championships, has looked as dominant as ever in the TYR Pro Swim Series in April, posting world-leading times in three different races. Ledecky, as you would expect, has been training extensively in the pool as she looks to add to her five Olympic gold medals in Tokyo this summer.
Serena Williams, Tennis
At age 39, Serena Williams is still chasing a record-tying, 24th Grand Slam victory in 2021. She has come close but has yet to win a major title since the birth of her daughter, Olympia in 2017, but no matter the tournament, Williams is still a threat to her opponents on the other side of the net. Widely regarded as the GOAT, Williams has demonstrated her superior fitness and strength over the course of her Hall of Fame career through her booming serves and powerful ground strokes.
Emma Coburn, Track and Field
Since 2016, Emma Coburn has proven to be a force in the women’s steeplechase on a global scale, with a bronze medal at the Rio Olympics, a gold at the 2017 world championships and a silver at the 2019 world championships. The pandemic limited steeplechase opportunities, but with personal bests in flat races including a 4:23.65 mile last summer, Coburn could become the first non-Black runner to break nine minutes for the 3,000-meter steeplechase this year. The 30-year-old is known for her commitment to fitness, mixing sprint workouts with weightlifting and mobility exercises on a daily basis.
Catarina Macario, USWNT and Lyon
Born in Brazil, 21-year-old Catarina Macario is quickly making a name for herself in the world of soccer, on both the U.S. women’s national team and Lyon. A former standout at Stanford, where she won two NCAA championships in 2017 and ’19, Macario has already shown her creativity on the pitch and ability to score goals with her superior speed and fitness.
Naomi Osaka, Tennis
After winning her second Australian Open title in February, Naomi Osaka has shown she is one of the best athletes in the world. The 23-year-old has won all four Grand Slam finals she has played, building her strength to boost her powerful serve while increasing her endurance through running workouts. With many years ahead and a continued desire to improve her fitness and on-court skills, Osaka is primed for a long, illustrious career.
Valentina Shevchenko, MMA
After dominating Jéssica Andrade at UFC 261, Valentina Schevchenko has cemented herself as one of the greatest pound-for-pound fighters of all time. The flyweight champion lost to Amanda Nunes by split decision at UFC 215, but is still creeping into the GOAT conversation in the women’s division. Standing at 5′ 5″ and 125 pounds, Schevchenko values her body’s recovery and rest, and believes in training once per day, at most, in preparation for her fights. Schevchenko’s speed in the Octagon has earned her a fitting nickname: the Bullet.
Shaunae Miller-Uibo, Track and Field
Undefeated in both the 400 meters and the 200 meters from 2018 through most of 2019, before she finished second at the 2019 world championships to Bahrain’s Salwa Eid Naser (who has since been provisionally suspended for missing three drug tests in a 12-month span), Shaunae Miller-Uibo is one of the world’s top sprinters. The Olympic schedule in Tokyo may prevent the Bahamian star from defending her Olympic gold in Tokyo, since the time between her two events is too close together, but that hasn’t stopped the 27-year-old from completing an intense training regimen, on and off the track.
Tia-Clair Toomey, CrossFit
There is no other woman in the world as successful as Tia-Clair Toomey at the CrossFit Games. The Australian native continues to make history in her sport, winning the Fittest on Earth title for four consecutive years from 2017 to ’20. An Olympic weightlifter who competed at Rio 2016, the 5′ 3″, 128-pound Toomey dominates a wide variety of events, from traditional powerlifting and swimming to pull-ups and more.
Mikaela Shiffrin, Alpine Skiing
Two-time Olympic gold medalist Mikaela Shiffrin has gone through the toughest stretch of her career over the past year, starting with the sudden death of her father and continuing through the COVID-19 pandemic, where she was unable to compete and sustained a back injury. But the 26-year-old Shiffrin endured those difficulties to return and capture four medals at the world championships in February. With that performance, Shiffrin, who is vehement when it comes to preparation and known for her intense workouts, tied the record for most career world championship medals with 11.
Claressa Shields, Boxing and MMA
In March 2021, Claressa Shields made boxing history when she defeated Marie-Eve Dicaire by unanimous decision to become the first boxer in the four-belt era to be an undisputed champion in two divisions. The self-proclaimed GWOAT, the Greatest Woman of All Time, Shields has the accolades to support the title, with two Olympic gold medals and professional world titles in three weight classes to her name. And if that wasn’t enough, in her quest to make more history, Shields has been training to transition to MMA and will make her debut in June 2021.
Amanda Nunes, MMA
After a first-round submission win over Megan Anderson at UFC 259, Amanda Nunes has put herself in a tier above everyone else in the women’s featherweight division. The 32-year-old Brazilian is ruthless against opponents in her sparring sessions and possesses unmatched strength and punching power. Nunes has been so dominant in the Octagon that she is running out of worthy opponents.
Simone Biles, Gymnastics
Despite not being able to compete for more than 18 months due to COVID-19, Simone Biles is still the hands-down favorite to bring home gold at the Tokyo Olympics this summer. The 24-year-old has already established herself as one of the most decorated and dominant gymnasts ever, amassing 30 medals between the Olympics and world championships. Don’t let her 4′ 9″ figure fool you—Biles consistently pushes the limits of her body and her sport, and the layoff has allowed her to refresh and add new skills to her repertoire, spelling trouble for all her opponents. Biles’s mastery of the vault, balance beam, floor exercise and more proves she’s an all-around athlete with an unmatched, diverse combination of power, flexibility, agility and strength.
Joe Kovacs, Track and Field
In 2020, U.S. shot putter Joe Kovacs showed off his quarantine fitness by squatting 320 kilograms (705 pounds) for a set of 10 reps. Last month he flashed a personal best by squatting 870 pounds for four reps. The 6-foot, 295-pound Kovacs won the 2019 world championships in Doha, Qatar, with a throw of 22.91 meters, which was the longest throw in 29 years and now could put Randy Barnes’s 1990 world record of 23.12 meters on watch.
Ariel Torres, Karate
With karate making its debut as an Olympic sport in Tokyo this summer, two-time USA Karate national champion Ariel Torres is poised to make his mark. Ranked No. 10 in the world and a top contender in kata, the karate discipline that means “forms” in Japanese, Torres’s workouts focus on breathing techniques and karate drills that require balance, power and mobility, all at once. The PhysioBall, resistance bands and unilateral exercises with kettlebells are all part of the 23-year-old’s workout arsenal.
Jim Walmsley, Ultra Running
At age 31, Jim Walmsley has established himself as not just one of the best U.S. ultra runners in history but one of the greatest in the world. An expert in endurance, Walmsley spent the early part of 2020 dropping way down in distance to run at the U.S. Olympic Trials, but then recycled some of that speed a year later to set a new 100K U.S. record in six hours, nine minutes and 26 seconds, missing the world record by just 12 seconds.
Fernando Tatis Jr., San Diego Padres
After making his MLB debut in 2019, Padres shortstop Fernando Tatis Jr. has rapidly become one of the hottest names in baseball. The 22-year-old slugger led his team to the postseason last year, ending the Padres’ 14-year playoff drought, and he is near the top of the league this season in home runs and stolen bases. The 6′ 3″, 217-pound Tatis is an outdoorsman who loves to post pictures of himself exploring and exercising in different nature destinations on his off days.
Bryson DeChambeau, Golf
Known for his methodical and mathematical approach to the game, Bryson DeChambeau is built unlike most golfers on Tour—and that’s all according to the 27-year-old’s plan. During the sport’s three-month break during the pandemic, the 6′ 1″ DeChambeau bulked up to 235 pounds, putting on an extra 20 pounds (most of it muscle) in his attempt to gain as much swing speed as he could. The 2020 U.S. Open champion and Tour’s biggest hitter focuses on developing strength through mobility and increasing power through isolation exercises.
Eliud Kipchoge, Marathon
There’s tangible evidence for 36-year-old Eliud Kipchoge’s physical fortitude, with world championship medals and a gold from the Rio Olympics that he’s looking to defend in Tokyo. His mental strength shines in the big moments, like when he became the first man to break two hours for the marathon in an exhibition race in Austria in 2019. It seems as though his 5′ 6″, 115-pound frame is manufactured for the 26.2 distance—in April 2021, Kipchoge made a 2:04 marathon look easy in a tune-up race for the Summer Games.
Jimmy Butler, Miami Heat
After taking only a single minute of rest and outlasting LeBron James in Game 5 of the NBA Finals, five-time All-Star Jimmy Butler further proved that he is one of the most well-conditioned athletes on the planet. The 31-year-old Butler, who has been on four teams over the past five seasons, has finally found a home with the Heat, an organization that shares his intense commitment to training and conditioning.
Italo Ferreira, Surfing
The reigning world champion, after the 2020 season was canceled due to the pandemic, Italo Ferreira has his sights set on winning a medal at the Tokyo Olympics in 2021. The 26-year-old Brazilian did not let lockdowns stop him from completing his oceanside weightlifting workouts and high-intensity training sessions that power his explosive, high-flying style in the water.
D.K. Metcalf, Seattle Seahawks
Before he was a second-round pick in the 2019 NFL draft, the 6′ 4″, 229-pound D.K. Metcalf made headlines with his performance in the speed, strength and agility drills at the combine—and with a shirtless photo that went viral. As a Seahawks receiver, Metcalf has proven that his freak physique translates to results on the field, as he finished in the top 10 in both receiving yards and touchdown receptions in 2020. And before next season, Metcalf is putting his speed to the test: The 23-year-old is slated to run against pro track stars in the 100 meters in an attempt to qualify for the U.S. Olympic Trials.
Mondo Duplantis, Track and Field
Once a high school sensation, 21-year-old Mondo Duplantis continues to push to new heights as a professional and could be favored for gold in the pole vault at the Summer Games in Tokyo. The 5′ 11″, 174-pound Duplantis is unbeaten since earning a silver medal at the 2019 world championships and has since broken the indoor pole vault world record twice. Last September, he also took down Sergey Bubka’s outdoor pole vault world best of 6.14 meters from 1994 with a 6.15-meter clearance.
Aaron Donald, Los Angeles Rams
A three-time NFL Defensive Player of the Year, Rams defensive lineman Aaron Donald trains like a powerlifter in the weight room while also placing special emphasis on agility drills to make sure he is quick enough to make tackles on the field. At 6′ 1″ and 284 pounds, Donald’s combination of explosive power and quickness has propelled him to becoming one of the greatest pass rushers of all time.
Sam Mikulak, Gymnastics
A two-time Olympian and six-time U.S. all-around champion, the 28-year-old Sam Mikulak has plans to retire after the Summer Games in Tokyo, but not before he chases some Olympic hardware. Standing 5′ 6″ and 140 pounds, Mikulak’s training regimen is an all-around effort, combining the repetitions of gymnastics skills with strength training, mobility exercises and a variety of recovery methods to protect his body from the constant impact.
Patrick Mahomes, Kansas City Chiefs
Despite losing Super Bowl LV to the Buccaneers, Chiefs QB Patrick Mahomes projects to be the face of the NFL for a long time. The 2018 MVP is known for his unorthodox medicine ball workouts, which allow him to be the game’s most creative quarterback and throw the football from seemingly any angle on the field.
Mohamed Salah, Liverpool
You do not have to go to Mohamed Salah’s Instagram to tell he is one of the most well-conditioned athletes in the world. The 28-year-old Salah, despite testing positive for COVID-19 in 2020, currently leads all Champions League forwards in distance covered on the soccer field and is second in minutes played. The Liverpool star loves swimming and training inside the pool on his off days.
Carlin Isles, Rugby
Don’t let the 5′ 8″, 165-pound frame fool you—Carlin Isles is widely known as the fastest rugby player in the world. Before he was a USA rugby sevens flyer and the team’s leading try-scorer ever (202), the 31-year-old was a high school star in football and track and field and an All-American in the 60-meter dash at Ashland University. After a disappointing finish at the Rio Games in 2016, Isles is focused on the Tokyo Olympics, training on the track with some of the top U.S. sprinters and challenging himself in the gym with a variety of intense (and sometimes unconventional) workouts.
Connor McDavid, Edmonton Oilers
Although his three-year reign as the NHL’s fastest skater ended in 2020, at the skates of Islanders center Mathew Barzal, Oilers center Connor McDavid is still one of the quickest in the league. The 24-year-old uses his speed to weave in and out of defensive lines like a magician, marrying his agility with incredible stickhandling and power. During the coronavirus lockdown in 2020, McDavid teamed up with former NHLer and trainer Gary Roberts to create a series of 15-minute at-home workouts, sharing his love for fitness with enthusiasts everywhere.
Noah Lyles, Track and Field
The reigning world champion in the 200 meters, 23-year-old Noah Lyles hates being compared to Usain Bolt, as he looks to forge his own legacy at his first Olympics this summer. His personal best of 19.50 in the 200 meters makes him the fourth-fastest man in history, and he’s also expected to give the 100 meters a shot at the U.S. Olympic Trials to see where his 9.86 PR stacks up.
Rafael Nadal, ATP Tennis
If you want to see the most fiery competitor in the sport of tennis, look no further than Rafael Nadal. The Spaniard turned pro in 2001 and is still going strong 20 years later, ranked No. 2 in the world with 20 Grand Slam singles titles to his name. In October 2020, he outlasted Novak Djokovic to win his 13th French Open, proving that his vigorous training and longtime commitment to maintaining his conditioning is still paying off.
Caeleb Dressel, Swimming
As he readies for the Summer Olympics in July 2021, U.S. sprint specialist Caeleb Dressel has followed a strict training regimen consisting of endurance and aerobic training in the pool, plus weightlifting sessions to build strength and explosive power—a distinctive trait the 6′ 3″, 190-pound Dressel demonstrates with his celebrated start off the blocks. After winning a record-breaking eight medals (six gold, two silver) at the 2019 world championships and showing off his improved speed in 2021 races, the 24-year-old could be primed for a big medal haul in Tokyo this summer.
Cristiano Ronaldo, Juventus
Juventus forward Cristiano Ronaldo is known for his intense work ethic and discipline, which helped him sculpt his famously shredded physique and chiseled six-pack. The 36-year-old Ronaldo, who took three weeks off after testing positive for COVID-19 last year, is inching closer to the international scoring record, which has been held by Ali Daei since 2006.
Jon Jones, MMA
After beating Dominick Reyes at UFC 247, Jon Jones now holds the record for the most UFC title fight wins with 14. Having accomplished everything he can in the light heavyweight division, the 6′ 4″, 205-pound Jones has now accepted the challenge of moving up weight classes in order to fight as a heavyweight (up to 266 pounds max), putting an even greater focus on his training and nutrition. Despite a 2018 doping violation and a 15-month suspension, Jones returned to the Octagon and would surprise no one if he added another belt to his already stellar résumé.
Derrick Henry, Tennessee Titans
“How do we stop Derrick Henry?” is a common question for opposing defenses in the NFL. The 27-year-old Titans running back is the reigning NFL rushing leader and almost single-handedly dragged his team to Super Bowl LIV. Henry is known for his intense workouts videos, where he showcases his 6′ 3″, 238-pound frame and the elite strength that makes him seemingly impossible to tackle each Sunday.
LeBron James, Los Angeles Lakers
Before suffering an ankle injury in late March, Lakers star LeBron James had been on a tear in his 18th NBA season. The 36-year-old James, fresh off winning his fourth NBA title and Finals MVP in October, was averaging close to 34 minutes per game this season along the way to becoming an MVP frontrunner. Standing at 6′ 9″ and 250 pounds, James is well-known for his training and recovery methods, which have allowed him to extend his basketball prime long past what many had expected.
Novak Djokovic, ATP Tennis
After winning a record ninth Australian Open title in January 2021, 33-year-old Novak Djokovic broke Roger Federer’s record for most weeks as the No. 1-ranked player in the world in March, and he is currently chasing the top of the list for most Grand Slam titles. The 6′ 2″, 176-pound Djokovic has a meticulous approach to training and nutrition that helps him in all aspects of his game, from sprinting speed, to hitting power and an unmatched flexibility on the court.
Giannis Antetokounmpo, Milwaukee Bucks
When Bucks star Giannis Antetokounmpo was drafted in 2013, he was regarded as a long-term project that many were unsure would pan out. But Antetokounmpo, rising from poverty in Greece, used his work ethic and intense training regimen to transform his rookie-year 6′ 9″ and 196-pound frame into a 6′ 11″ and 242-pound, intimidating physique that earned him two-time NBA MVP honors. The 26-year-old, who recently signed the richest contract in league history, is an all-around force on the court for the Milwaukee. There’s no arguing that he’s more than deserving of the Greek Freak title.