Just how jacked can San Francisco 49ers quarterback Colin Kaepernick become?

His coach doesn't want to find out.

Jim Harbaugh recently told Matt Maiocco of CSNBayArea.com that he would prefer Kaepernick ease up in the weight room so as to not lose any of his signature speed. This concern over becoming "too strong" isn't something you hear often in the NFL, but it makes sense in this case.

"If you're just talking about weightlifting and upper-body strength, yes, I think there is that fear." Harbaugh said. "It's something we've talked about. 'I don't want you getting too jacked-up, Colin.' I want some speed, quickness, not just (flexing chest his muscles)."

Kaepernick has reportedly hit the gym hard since losing a heartbreaking Super Bowl game to the Baltimore Ravens. But it's not like the third-year quarterback needs to bulk up much more. He is, after all, the same guy whose throws are so hard that they dislocated one of Randy Moss' fingers.

(H/T to Larry Brown Sports)