(Photo credit: Jayne Kamin-Oncea-Imagn Images)

Rams quarterback Matthew Stafford missed Monday's practice in an unexpected development as he continues to nurse a back injury.

Los Angeles coach Sean McVay declared over the weekend that the 37-year-old signal-caller would participate in his first training camp practice on Monday.

Instead, Stafford was dressed in street clothes and reporters observed him stepping into an Airstream-type trailer known as an Ammortal chamber at the team's training complex in Woodland Hills, Calif.

The Ammortal chamber is advertised as a 'wellness device that aims to optimize human performance and promote holistic health through a combination of non-invasive technologies.'Stafford is dealing with an aggravated disc in his back, which has limited his preparation as he heads into his 17th season.

In his absence, Stetson Bennett IV threw for 188 yards and two touchdowns in Saturday's 31-21 preseason win against the Dallas Cowboys in Inglewood, Calif.

The Rams open the regular season on Sunday, Sept. 7, with a visit from the Houston Texans.

Stafford completed 340 of 517 passes (65.8 percent) for 3,762 yards, 20 touchdowns and eight interceptions last season while starting all 16 games in which he appeared.

A two-time Pro Bowl selection, Stafford has completed 63.4 percent of his passes for 59,809 yards, 377 TDs and 188 interceptions in 222 regular-season games (all starts) with the Detroit Lions (2009-20) and Rams. He ranks 10th all-time in touchdown passes and passing yardage -- and second to Aaron Rodgers among active quarterbacks. The Lions selected him with the first overall pick of the 2009 NFL Draft out of Georgia.

Stafford led the Rams to a 23-20 win over the Cincinnati Bengals in Super Bowl LVI.

--Field Level Media