Prior to “Rocky,” boxing matches in movies played static. You could set up dolly tracks outside of the ring to give viewers a sense of fluidity, but anything inside the ring was probably going to be handheld or on sticks. This didn’t mean you couldn’t film a memorable boxing match (Mark Robson’s 1949 noir “Champion” closes with a viscerally unsettling bout); you just weren’t going to give moviegoers anything they hadn’t seen.
Garrett Brown’s 1975 invention of the Steadicam changed this. One year later, masters like Hal Ashby and John Schlesinger added the newfangled rig to their technical palette in, respectively, “Bound for Glory” and “Marathon Man.” But the stabilized camera was practically tailor-made for “Rocky.” Avildsen could get inside the ropes with Stallone and Carl Weathers to give audiences a face-mangling, rib-cracking fight for the ages. But doing so would require the director to film the bout twice and in reverse.
Per Adam K. Raymond’s 40th anniversary appreciation of “Rocky” for Yahoo! Movies:
“When the big day arrived, Avildsen began by shooting the final round first. This allowed the gradual removal of the makeup and prosthetics Stallone and Weathers needed to make their faces look like they’d been through 15 rounds. The actors performed each round twice, once with cameras shooting through the ropes from outside the ring — a touch Avildsen said added to the realism — and another time with Steadicam operator Garrett Brown circling them in the ring.”