Now we know why the San Francisco 49ers signed a couple of running backs. 49ers head coach Kyle Shanahan said on Thursday that running back Isaac Guerendo tore his pectoralis muscle a month ago while lifting weights. Shanahan says Guerendo could be ready at the end of training camp.
Guerendo has had flashes of being a solid running back for the 49ers. In his rookie season, there were numerous plays indicating he could be something special—if only he could stay healthy. The pec tear joins a list of injuries
over his two years in the league, including groin, foot sprain, ankle, and shoulder injuries.
After a 2024 that showed some optimism, Guerendo was quiet in 2025. He played in 14 games with zero offensive snaps and five kick returns. Many thought his second year would be the year he’d take a lot of the load off Christian McCaffrey, but Guerendo didn’t see the field.
Guerendo is entering the third year of his four-year rookie deal. The 49ers signed both Jordan Mims and Jemar Jefferson earlier Thursday, and now the reasoning makes a bit more sense. The two recent signings will join 2026 third-round pick Kaelon Black to compete for a role behind McCaffrey—making one wonder what the future holds for Guerendo with the injuries.
