Tennessee walk-on running back Jayson Sparks was the only healthy player in the backfield for Tuesday’s practice.

Jalen Hurd hasn’t participated in any contact drills┬áthis spring as he returns from shoulder surgery, and Alvin Kamara missed Tuesday’s practice due to a thigh bruise.

It affected how much the Vols could accomplish in practice, coach Butch Jones said, but he’s hopeful that Kamara will return Thursday, or Saturday at the latest.

Justus Pickett chose to transfer after he was academically ineligible for the TaxSlayer Bowl. Derrell Scott also will transfer. Both players saw limited playing time last season.

The injuries at running back only underscores Jones’ recent insistence that the recent momentum behind Tennessee as an SEC contender in 2015 may be premature, given the team’s lack of depth at some spots. Perhaps the Vols will stay very healthy during the fall, and more players will arrive this summer from the 2015 class, but an injury or two could lead to a huge downgrade in talent.

Jones has spoken highly of Sparks, who is 5-foot-8 and 175 pounds, but he’s not on the same level as Kamara, a junior-college transfer, and Hurd.

Hurd did get in some non-contact work Tuesday and then spoke with the media.

“I see some different stuff watching it all, tips that when I get in the game, I can improve on myself,” Hurd said.

The running back also confirmed that Tennessee has installed a few packages where Hurd and Kamara are on the field at the same time. Hurd, who now weighs 235 pounds, also said he’s a stronger runner than Kamara, who is more elusive.