Cristiano Ronaldo strips down for sub-zero fitness routine

At the start of the year, Manchester United missed the services of Cristiano Ronaldo for several weeks. Now that he's back, the Portuguese star is making sure that he is doing everything he can to keep his body in its best shape. He finally returned to active duty for the Red Devils in late January, and has recently taken to social media to show fans his impressive physique and a glimpse into his sub-zero treatments that are meant to keep him away from further injuries.

The 36-year-old forward is smashing through all the earlier misconceptions about a footballer's ability to stay at the top level in the mid-30s. Very few outfield players have been able to maintain top form as they get to this age, and Ronaldo has revealed some of his secrets to almost 400 million Instagram followers.

On Thursday, the five-time Ballon d'Or winner took to the popular social media platform to lead fans through a maze of low temperature treatment rooms, which he said were meant to aid in his recovery.

It was an interesting maze of rooms that appear to be getting colder and colder as he opened more doors. He showed off his chiseled frame as he entered the facility wearing only a pair of boxer briefs, gloves to protect his hands, a head cap, and face mask.

It is not uncommon for professional athletes to take a dip in ice baths and receive cryo treatments, but these are often done behind the scenes under the watchful eyes of the club's physiotherapists. Ronaldo's fans are delighted to have a rare glimpse into the hard work that their favourite player puts in to stay in shape.

Ronaldo re-joined Manchester United last summer, after leaving the club way back in 2009 to join Real Madrid. He has since made himself a legend across Europe, but it is clear that he is not planning on winding down his career anytime soon.

The Red Devils are dealing with an internal crisis at the moment due to the suspension of Mason Greenwood, but Ronaldo will surely be determined to get past the problem and help the club get into the UEFA Champions League spots. They are currently in a four-way battle against West Ham, Arsenal and Tottenham Hotspur for the coveted slot, and a single slip will send them straight into the Europa League.

Manchester United will be facing Middlesbrough in the FA Cup on Friday, and will resume Premier League action against Burnley next week.