Michael Schumacher's family has asked for understanding as it continues to keep details of his health private ahead of the seven-time Formula One champion's 50th birthday.

In a statement published on Facebook on Wednesday, one day before his birthday, the family says: "You can be sure that he is in the very best of hands and that we are doing everything humanly possible to help him. Please understand if we are following Michael's wishes and keeping such a sensitive subject as health, as it has always been, in privacy."

No details on Schumacher's current health were given. The former F1 champion suffered serious head injuries in an accident while he was skiing with his teenage son Mick in the French Alps at Meribel on Dec 29, 2013.

Schumacher hit the right side of his head on a rock, splitting open the helmet. Doctors worked to remove blood clots from his brain, but some were left because they were too deeply embedded. Schumacher's condition stabilized after he was placed in a drug-induced coma, from which he later emerged.

Updates on his health have been scarce since he left hospital in September 2014 to be cared for privately at his Swiss home on the shores of Lake Geneva.

"Michael can be proud of what he has achieved, and so are we!" the family said in the statement Wednesday.

"That's why we remember his successes with the Michael Schumacher Private Collection exhibition in Cologne, by publishing memories in social media and by continuing his charitable work through the Keep Fighting Foundation. We want to remember and celebrate his victories, his records and his jubilation."