Christian McCaffrey’s latest effort to get a leg up on his competition is a real head rush. The 49ers star revealed over the weekend he’s now training his body upside down in order to prep it for its 10th NFL season. McCaffrey shared on his Instagram page on Sunday that during a recent get-together with surfing legend Laird Hamilton, he spent some time dangling from his feet. Christian McCaffrey shared on his Instagram page on Sunday that during a recent get-together with surfing legend Laird Hamilton, he spent some time dangling from his feet. Instagram / @christianmccaffrey A photo the San Francisco running back shared showed McCaffrey hanging by some cloth, while Hamilton proudly looked on from feet away. McCaffrey appeared to be a bit uncomfortable in the position, though in other snaps he posted from the hangout with Hamilton, it was clear he loved his time with the 62-year-old icon so much, he was down to try another workout that required him to wear a device on his head.…