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Original Issue

THE FITTEST 50

Every sport makes different demands, but success at each often hinges on conditioning. Which athletes were best prepared in 2018? SI picked—and ranked—them

MEN

1 SAQUON BARKLEY

Giants Pro Bowl running back

IF THERE was a rookie milestone to clear in 2018, you could count on Barkley to hurdle it. With breakout speed, punishing power and acrobatic moves—and those muscular quads—the 21-year-old workhorse became only the third first-year back to eclipse 2,000 yards from scrimmage.

2 CRISTIANO RONALDO

Five-time Ballon d'Or winner

3 GIANNIS ANTETOKOUNMPO

Two-time NBA All-Star

4 NOVAK DJOKOVIC

Winner of 14 tennis majors

5 KEVIN MAYER

Decathlon world-record holder

6 MAT FRASER

Three-time CrossFit Games champion

7 LEBRON JAMES

Four-time NBA MVP

8 JORDAN BURROUGHS

Wrestling gold medalist

9 CONOR MCGREGOR

UFC fighter, featherweight and lightweight; boxer

10 CANELO ÁLVAREZ

Multiweight boxing champion

11 AARON DONALD

2017 NFL Defensive Player of the Year

12 LUKA MODRIĆ

2018 Ballon d'Or winner

13 RUSSELL WESTBROOK

2017 NBA MVP

14 PATRICK LANGE

2018 Ironman world champion

15 TOMMY CALDWELL

Free-solo rock climber

16 KJELD NUIS

Two-time speed skating gold medalist

17 GIANCARLO STANTON

Yankees All-Star outfielder

18 PATRICK MAHOMES

Chiefs Pro Bowl quarterback

19 HAMISH BOND

World champion rower, cyclist

20 CONNOR MCDAVID

Oilers All-Star center

21 ELIUD KIPCHOGE

Marathon world-record holder

22 CAELEB DRESSEL

Two-time swimming gold medalist

23 JIM WALMSLEY

U.S. ultrarunner

24 GERAINT THOMAS

2018 Tour de France winner

25 BROOKS KOEPKA

World No. 1 golfer

WOMEN

1 SIMONE BILES

Four-time Olympic gold medal gymnast

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 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.

2 CATERINE IBARGUEN

Colombian triple jumper

3 TIA-CLAIR TOOMEY

Two-time CrossFit Games champion

4 DINA ASHER-SMITH

British world champion sprinter

5 GWEN JORGENSEN

2016 Olympic champion triathlete, marathoner

6 KATIE LEDECKY

U.S. gold medal swimmer

7 AMANDA NUNES

UFC bantamweight, featherweight champ

8 DANIELA RYF

Four-time Ironman world champion

9 EMMA COBURN

2017 steeplechase world champion

10 SERENA WILLIAMS

23-time major tennis titlist

11 BREANNA STEWART

2018 WNBA MVP

12 COURTNEY DAUWALTER

American ultrarunner

13 CASTER SEMENYA

Two-time 800-meter gold medalist

14 MARY KEITANY

Kenyan marathoner

15 EMILY REGAN

Four-time rowing world champ

16 HILARY KNIGHT

U.S. ice hockey Olympic champion

17 KAILLIE HUMPHRIES

Two-time bobsled gold medalist

18 MIKAELA SHIFFRIN

Reigning World Cup ski champion

19 SASHA DIGIULIAN

U.S. rock-climbing champ

20 LINDSEY VONN

Four-time World Cup ski champion

21 MAGGIE STEFFENS

U.S. Olympic water polo champ

22 CAROLINE WOZNIACKI

2018 Australian Open winner

23 JESSIE DIGGINS

Cross-country skiing gold medalist

24 JULIE ERTZ

U.S. soccer World Cup champ

25 CLARESSA SHIELDS

Two-time Olympic boxing gold medalist

THE EXPERTS

MICHAEL JOYNER

Human performance expert, Mayo Clinic

SUE FALSONE

Physical therapist, athletic trainer and author

CHRISTOPHER LUNDSTROM

Exercise physiologist, coach of elite distance runners

DAVID HESSE

Vice president for performance, IMG Academy

ROY HOLMES

EXOS performance manager, CSCS

THE CRITERIA

With the help of a panel of experts (opposite page), athletes were ranked based on their performances over the last 12 months, the demands and risks of their sport, durability, training regimens, and physical benchmarks including power, speed, strength, agility, endurance and flexibility.

FOR MORE ON THESE INCREDIBLE ATHLETES, GO TO SI.COM/FITTEST50