Proximate cause consists of cause in fact and foreseeability. See Leitch v. Hornsby, 935 S.W.2d 114, 118 (Tex. 1996). The foreseeability of a back injury in connection with the regular lifting of heavy objects is judged by a reasonable person standard. Id. at 119. In a case like this one, where there is no medical testimony linking the alleged negligence to the injury, a claimant must provide probative evidence, through expert testimony, connecting the injury to the alleged negligence. Id.