Reporters got a sneak peek at part of UCLA football practice that coach Chip Kelly probably didn’t want them to see

One UCLA defensive back after another lurched toward the tackling dummies, wrapping their arms around the blue foam and wrestling them to the ground.

After a few repetitions, the thudding of bodies was interrupted by the booming voice of defensive line coach Vince Oghobaase.

“We did it in the spring!” the irritated coach shouted Friday morning on the Bruins’ opening day of fall camp. “Now do it!”

Oghobaase then opted to show, not yell. He plunged his 6-foot-5 frame, last listed at 303 pounds during an NFL tryout eight years ago, into a dummy and rolled around on the ground with it firmly in his grasp.

The scene played out a few steps from a group of reporters allowed to watch part of the Bruins’ first practice, but it might be the only drama the media gets to witness before the season opener Sept. 1 against Cincinnati at the Rose Bowl.

UCLA coach Chip Kelly has closed practices with the exception of a 20-minute window that includes stretching and some drills. Reporters were granted access to a second chunk of the roughly hour-long practice Friday because of a mix-up involving which portion of the session they were supposed to watch.

It’s the first time UCLA has closed fall camp to the media going back to at least the start of the Karl Dorrell era in 2003. Kelly did not speak with reporters to explain his policy, though he’s scheduled to talk Saturday as part of twice-weekly availability.

Access is also being limited in other ways. Assistant coaches are not being made part of the regular interview rotation and players available to the media have been selected by school officials for the first nine days of camp.

Most of UCLA’s spring practices were open to the media and public, but Kelly was known for restricting access during his final two seasons at Oregon in 2011 and 2012.

The parts of Friday’s practice that were observable were mostly a blur.

Left tackle Andre James said the Bruins already were moving at a swifter pace after a host of player-run practices and offseason workouts under the guidance of Frank Wintrich, the team’s new director of football performance.

“Where we were in the spring compared to coming out today, we were a lot better,” James said. “We’re always trying to pick up the pace. That’s our goal, just every day come out a little faster and be a little better.”

James and safety Adarius Pickett praised a sports science program that encourages players to get at least eight hours of sleep and monitors their heart rate and distance traveled in practices with tracking devices. The result, the players said, is accelerated recovery and increased energy.

“Everything is calculated, everything is scientific,” Pickett said.

The Bruins’ offensive players bounded onto the field wearing blue jerseys that more closely resembled those the team wears during games as opposed to the darker shade they had worn during practice in previous years. Freshman defensive lineman Atonio Mafi was the only player wearing a yellow jersey, denoting that he was recovering from an injury.

Linebackers Jaelan Phillips and Josh Woods were among the players back from the injuries that slowed them in spring practice, and fellow linebacker Mique Juarez appeared noticeably slimmer than he’d been in the spring.

It was the UCLA practice debut for a host of newcomers including quarterbacks Wilton Speight and Dorian Thompson-Robinson, who will battle incumbent Devon Modster for the starting job. Speight and Modster appeared to be working with the first team during the limited portion of practice the media was allowed to watch.

Zach Sweeney and converted defensive lineman Boss Tagaloa are vying to become the starting center, with Sweeney getting first-team repetitions Friday. James said Justin Murphy, a graduate transfer from Texas Tech, has been moving around the offensive line and “could definitely play great at tackle.”

The Bruins appeared upbeat for a team picked to finish fourth in the Pac-12 Conference’s South Division after a 6-7 season that led to the hiring of Kelly.

“Coming out, first day,” James said, “the dudes were excited to put on a helmet and start running around.”

Given the viewing constraints, it was one of the few things for which reporters didn’t have to take his word.

ben.bolch@latimes.com

Follow Ben Bolch on Twitter @latbbolch