Baseball superstar Bryce Harper has a THIRD of his blood removed in wacky offseason procedure

Phillies first baseman Bryce Harper has shocked fans by revealing that he has undergone a bizarre offseason procedure to remove a third of his blood from his body.

Fear not, though, baseball fans - it was returned soon after, but is just the latest cutting-edge medical treatment finding its way into the top level of sport.

Taking to Instagram, the 33-year-old - seemingly in the hope of finding a way to elongate his career and improve his health - posted a photo of himself hooked up to machines, alongside his doctor.

'EBOO is a procedure in which 1/3 of your blood is drawn from your body, passed through a filtration and ozonation device, and then returned to your bloodstream,' he explained, in a now-viral post. 

He then went on to explain all the benefits, revealing: 'Circulates your blood outside your body. Exposes the blood to ozone (O₃) and will oxygenate or filter the blood before returning it to you.

'This will: Improve circulation, Reduce inflammation, Fight infections, Support immune function, Remove toxins, Increase energy. 

Bryce Harper has undergone a bizarre offseason procedure that removed a third of his blood

Bryce Harper has undergone a bizarre offseason procedure that removed a third of his blood

Phillies star Harper is on a monster $330million contract that will end when he is 39 years old

Phillies star Harper is on a monster $330million contract that will end when he is 39 years old

'My guy @drjoshredd is a magician. Had a great week of wellness starting with this awesome machine. More videos to come of other things as well.'

It is as yet unclear which 'other things' Harper is referring to, but the Phillies will certainly be hoping the medical procedures can boost the health of its $330million superstar, who is contracted through 2031 - by which time he'll be 39.

Harper is far from the first athlete to experiment with cutting-edge medical technology in a bid to get ahead of his rivals.

Legendary NFL quarterback Tom Brady is perhaps the most famous, with his biohacking efforts and Blood Flow Restriction (BFR) treatment.

Brady, who played at the top level until he was 45, has been extremely open about his regimen, which includes a strict diet, saunas, supplements, and meditation.

Cristiano Ronaldo is showing no signs of slowing down despite being 40 years of age

Cristiano Ronaldo is showing no signs of slowing down despite being 40 years of age 

Tom Brady's health-conscious mindset has kept him extremely fit even post-retirement

Tom Brady's health-conscious mindset has kept him extremely fit even post-retirement 

Elsewhere, LeBron James is rumored to spent over $1.5million a year on ways to improve his health, including cryotherapy and hyperbaric oxygen chambers.

Cristiano Ronaldo is another health-conscious top-level athlete, and his efforts have allowed him to remain at the top of his game at the age of 40.

He is reported to use whole-body cryo chambers, and can take up to six naps a day in an individually-calculated sleep cycle.

It is estimated that he spends over $1m a year on body maintenance to ensure that he is ready to compete at the top level.