Ronaldo ahead of James and Federer

With insight from the panel of trainers, strength and conditioning coaches and performance experts, Sports Illustrated identified the fittest athletes in the world and their findings reveal that Real Madrid superstar Cristiano Ronaldo is the king of fitness.

LeBron James, indisputably the best basketball player in the world, was ranked second while Swiss Maestro Roger Federer surprisingly came in at third.

Weightlifter Mat Fraser came in at fourth while NFL linebacker James Harrison and receiver Odell Beckham Jr ranked fifth and sixth respectively.

Oklahoma City Thunder's explosive point guard Russel Westbrook, sprint star Wayde van Niekerk and MMA fighter Conor McGregor rounded off the top 10.

Rafael Nadal came in 20 spots behind Federer, while WWE's John Cena was ranked 24th.

Other notable athletes on the list include cyclist Chris Froome (12th) and Chelsea midfielder N'Golo Kante (48th), while Indian cricketer Virat Kohli's exclusion raised many eyebrows.

Athletes were considered based on performances in the last 12 months, demands and risks of their respective sports, training regimens, longevity and physical benchmarks, including: speed, strength, endurance, agility, flexibility and power.