People are just realising important reason Cristiano Ronaldo always wears nail polish on feet

Cristiano Ronaldo went viral earlier this week when fans noticed he was wearing nail polish. But it turns out there's an important reason why he does it.

Earlier this week, the football legend uploaded a post-workout snap with his 13-year-old son Cristiano Jr to Instagram.

The father and son duo posed with huge smiles across their faces as they stood topless in what appeared to be a home gym.

However, Ronaldo's followers were a little distracted by his toenails, which they were quick to point out were painted with black nail polish.

Yasser Bakhsh/Getty Images

One user wrote in the comments: "Is no one going to talk about the black painted nails?"

Another added: "Okayy but did someone notice the black nail polish on Ronaldo's feet?"

And a third said: "Why bro got black toe nails?"

But there's actually a perfectly good reason for it.

Instagram/@cristiano

Athletes can be really susceptible to fungal infections around their toenails due to spending endless hours each day sweating in shoes.

The problem is particularly common in footballers, whose feet take a good deal of trauma when they're tackled or stepped on during matches.

So, Ronaldo paints his toenails to protect them from fungi and bacteria.

It certainly seems to be working for the 39-year-old, who's on top form, scoring 33 goals in 34 games so far this season for Saudi Pro League club Al Nassr and the Portugal national team.

And he's not the only one getting regular pedicures in the name of protecting his little piggies.

During the height of his boxing career, Mike Tyson used to paint his nails and it's also a common practice among MMA fighters and track runners.

Instagram/@cristiano

In other news, Cristiano Jr. appears to be following in his famous father's pedicured footsteps, having played at several academies before joining Al Nassr's books.

The U13s player said: "I am very happy to have come here and I feel comfortable with [Al-Nassr], and I adapted quickly and enjoyed a lot during the current season, thank God."

And, he's demanding his dad keeps playing for a few years longer so they can one day take to the pitch together.

Ronaldo previously said: "My son tells me: dad, hold on a few more years. I want to play with you!"

At the recent Globe Soccer Awards, he joked: "The moment I finish, I don't know to be honest. Of course it will be soon, soon I mean 10 years more. No I am joking, I don't know, let's see."