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49ers running back Isaac Guerendo is recovering from a torn pectoral muscle

The story of the San Francisco 49ers‘ 2025 campaign was injuries, which just so happens to be what the story of the 2024 season was, too. Whereas the 2024 team succumbed to its injuries, last year’s squad managed to overcome its injury woes to make a run all the way to the divisional round of the playoffs.

Simply put, San Fran is hoping to stay relatively healthy in 2026 because if it can, it has a legitimate shot at making a Super Bowl run. Fans of the team are going to want to shield their eyes, though, because head coach Kyle Shanahan recently revealed that running back Isaac Guerendo suffered a serious injury, even though the team isn’t even playing games currently.

Isaac Guerendo Recovering from Torn Pectoral Muscle

A fourth-round pick in the 2024 NFL Draft, Guerendo was one of the lone bright spots for the team as a rookie. With both Christian McCaffrey and Jordan Mason battling injuries, that thrust Guerendo into action sooner than expected, but he managed to flash his potential whenever he found his way onto the field (84 CAR, 420 YDS, 4 TD, 15 REC, 152 YDS).

While Mason departed for the Minnesota Vikings last offseason, McCaffrey was fully healthy for the 2025 campaign, and the team picked up Brian Robinson Jr. in a trade with the Washington Commanders, which put Guerendo back in the No. 3 spot on the depth chart. While he was active for 14 games, Guerendo didn’t log a single statistic of note last year on the offensive side of the ball.

Heading into the new season, though, Guerendo appeared to have a real shot at earning the No. 2 gig behind McCaffrey, as Robinson signed with the Atlanta Falcons in free agency. However, Shanahan recently revealed that Guerendo suffered a torn pectoral muscle in April, which will keep him on the sidelines until late in training camp.

“49ers HC Kyle Shanahan said RB Isaac Guerendo tore his pectoral while lifting weights and he’s expected to be out until late in training camp,” Ari Meirov of The 33rd Team shared in a post on X.

49ers Won’t Love This Isaac Guerendo Injury Update

GettySan Francisco 49ers RB Isaac Guerendo

The silver lining here is that Guerendo still could be ready to go for the start of the season. Considering how many injuries this team has dealt with in recent years, though, this just isn’t the sort of news anyone in San Francisco wants to hear. Guerendo has battled his fair share of ailments to begin his career, too, so from an individual perspective, this is another tough blow for him.

With Guerendo out, Jordan Jones and third-round rookie Kaelon Black will spend much of the summer battling it out for the backup job behind McCaffrey. Guerendo has more NFL experience than either of those guys, but the time he’s being forced to spend recovering from this injury is going to put him at a disadvantage. Guerendo could still earn the No. 2 spot on the running back depth chart, but this position has suddenly become much more intriguing in the blink of an eye.