Kaepernick has been busy in the gym during the off-season.
San Francisco 49ers coach Jim Harbaugh has warned quarterback Colin Kaepernick not to get “too jacked up” during the off season.
Kaepernick wasted little time in getting back in the gym following the 49ers’ Super Bowl defeat to Baltimore Ravens in New Orleans last month.
However, Harbaugh is worried that his new franchise quarterback may be working too much on bulking up too quickly.
“If you’re talking just about weightlifting and upper-body strength, yes, I think there is that fear,” he told Comcast SportsNet Bay Area.
“it’s something we’ve talked about. ‘I don’t want you getting too jacked up, Colin.’ I want some speed, quickness and not just (flexing his muscles).”
Kaepernick completed 62 per cent of his passes with 10 touchdowns and three interceptions last season after taking over the role of starter from Alex Smith in Week 10.
However, there is a fear he may be working too hard on his upper-body strength when his throwing arm is as strong as it needs to be already.
Team-mate Michael Crabtree revealed that wide receivers on the roster are even trying to stay away from the 25-year-old in warm-ups as there is a “lot of heat coming”, as reported by NFL.com.
Kaepernick has always been a hard-worker in the gym, especially during the off-season, but the 49ers will hope it will benefit rather than hinder him ahead of the new campaign.