The courageous story of the "Flying Sikh" -- India's most successful ever track athlete, who overcame childhood tragedy to seek Olympic glory -- is the latest Bollywood biopic to hit cinemas.

"Bhaag Milkha Bhaag" (Run, Milkha, Run) charts the journey of young Milkha Singh who lost his family during India's tumultuous partition in 1947 and went on to compete at the 1960 and 1964 Olympic Games.

His rise to elite athlete made Singh a national hero and the film, which opens in theatres worldwide on Friday, joins the Bollywood trend of movies based on or inspired by real stories.

"We all grew up with the folklore of Milkha, he's a larger-than-life figure for us," said the film's director Rakeysh Mehra.

"He's like what Pele meant to football, or what Jesse Owens meant for track and field for the West."

The movie title refers to the poignant last words spoken to Singh by his father. As he was dying, he told Singh to flee or he too would be killed in the post-partition riots sweeping the subcontinent -- Singh ran for his life and boarded a train with other refugees.

Mehra was drawn to Singh's story not just for his sporting achievements but for the impact the athlete had on a newborn nation struggling to assert itself.

"At that time, we were looking for heroes outside politics. Outside (Mahatma) Gandhi or (prime minister Jawaharlal) Nehru, there were none that the world knew. So he went out there and in a way conquered the world for us," he explained.

"This man never ran away from his fears, he ran along with them."

Singh finished fourth in the 400 metres at the 1960 Olympics in Rome after a spectacular final that was so close it needed a photo finish to determine fourth place. A devastated Singh, who won gold at both the Asian and Commonwealth Games, never fulfilled his dream of winning an Olympic medal.

The director says his film is decidedly "un-Bollywood", deviating from the typical plotline that aims to "serve a complete meal" by combining elements of dance, drama, emotion and action into one blockbuster.

"Here, drama is the key," Mehra said.

He is the latest Bollywood director to experiment with a biographical story, following a string of true-life movies in recent years that have proven popular with wide audiences.

Among the most successful was "The Dirty Picture" (2011), starring Vidya Balan and inspired by the life of a South Indian erotic actress in the 1980s.

Last year's critically-acclaimed sports biopic "Paan Singh Tomar", starring Irrfan Khan, told the story of athlete Tomar who became a notorious bandit.

Currently in the pipeline are movies about playback singer Kishore Kumar and boxing star Mary Kom, a farmer's daughter who became a five-time world champion and won a bronze medal at the London Olympics.

Farhan Akhtar, who plays Milkha Singh in the new movie, said portraying a living person was a huge responsibility that required months of both physical and mental preparation.

"I wanted them to believe that they've cast an athlete and taught him how to act, as opposed to the other way around. And that comes from the kind of energy you exude when you walk onto a track and it feels like you belong to this space," he said.

The former sprinter, now 77, told Akhtar he hoped the film would encourage future Indian athletes by showing just how close he came to Olympic glory, and perhaps inspiring them "to fulfil that dream for him", the actor said.