In need of a good cry? Science has found the perfect movie for you.

Researchers say the two-and-half-minute climax of the 1979 boxing flick "The Champ" is the most reliable way to open the waterworks for even the most hardened, cynical viewer.

In the scene, washed-up boxer (is there any other kind?) Jon Voight returns to the ring to fight for the custody of his son (a very young Ricky Schroder).

In the scientifically proven heart-wrenching climatic scene Schroder pleads "Champ! Wake up!" after Voight's character dies after a gruelling fight in the ring.

Sports, fathers and death have long been known to be the holy trifecta for tears.

Two psychology professors in the U.S., James Gross and Robert Levenson, have been working since 1988 to find the perfect sad film clip so they can use it on test subjects in experiments on how sadness affects behaviour.

"‘The Champ' . . . produced levels of sadness that were much greater than any other emotion," the researchers wrote in an article.

They evaluated over 250 movies and film clips before whittling down the list to 78 contenders for the saddest movie ever title.

"The Champ" eventually defeated "Kramer vs. Kramer."

While a "saddest movie title" might sound superfluous, it actually is quite helpful to social scientists.

Ethics mean psychologists can't trick a subject into thinking something awful has happened in order to induce feelings of sadness. But people are perfectly willing to pay money to cry in a theatre and then walk out minutes later with no long-term emotional damage done, making movies a easy and ethical way for scientists to get those tears.

Chances are you have not heard of "The Champ" and there might be good reason for that. Critics have not been kind to "The Champ," which scores a lowly 38 per cent rating on Rotten Tomatoes.

"The tear-jerking is so determined and persistent that your ducts feel as if they'd been worked over with a catheter," Dave Kehr of the Chicago Reader wrote.

You can take "The Champ" tear challenge here. And read the comments below for what movies would make our readers cry.