Top 10 Sports Illustrated First-Ever Fittest 50 Athletes; Roger Federer, Rafael Nadal, Georges St-Pierre Also Make the Cut

Real Madrid's Cristiano Ronaldo (R) celebrates with team mate Alvaro Morata (L) after scoring a penalty against Atletico Madrid during their Champions League final soccer match at the Luz Stadium in Lisbon May 24, 2014. REUTERS

Sports Illustrated (SI) has unveiled the list of the fittest athletes in the world. Some of the top athletes in different sport disciplines have made it to SI's inaugural list, which was determined based on four unique criteria such as strength, speed, endurance, and agility.

How do the world's greatest athletes fare with other high intensity athletes? Here's the top 10.

Athlete (Overall Score)

1. Lebron James (40)

2. Cristiano Ronaldo (38.5)

3. Usain Bolt (36.5)

4. Floyd Mayweather (36)

5. Dez Bryant (35)

6. Calvin Johnson (34.5)

7. Serge Ibaka (34)

8. Adrian Peterson (33.5)

9. Jon Jones (33)

10. Michael Phelps (33)

The fastest man on earth, Usain Bolt, has received an overall score of 36.5 out of 40. Agility, endurance, and strength were the categories where Bolt fell just short of SI's top two. In 2013, Bolt revealed his rigorous training and diet secrets to Details.com. Bolt reportedly spends 90 minutes in the gym to maintain his healthy and lean physique. As for his diet, he eats healthy food and tries not to eat fast food for long periods.

Real Madrid superstar Cristiano Ronaldo is at the second spot. He scored 10 in three categories including speed, endurance, and agility. He fell short when it comes to overall strength.

King James claimed the top spot. According to SI, no other athlete deserves the first place other than Cleveland's prodigal son. He scored a perfect 10 in all four criteria. "James has the build of Malone and the speed and agility of Iverson." For his stamina, James has played a total of 1000 games in 11 seasons averaging 40 minutes per game for his basketball career. SI said that James is the only athlete who can get away playing other sports and excel in them.

Other athletes who made it to the list include top-ranked athletes in the sporting world of tennis, Roger Federer and Rafael Nadal, who are positioned at the 31^st and 20^th places, respectively. Semi-retired Ultimate Fighting Championship (UFC) fighter Georges St-Pierre is the second mixed martial artist on the list. St-Pierre is at the 25^th spot. Another UFC fighter Jon Jones has made it to the top 10 behind Minnesota Vikings' Adrian Peterson.

For the complete list, visit SI.com.