dissenting.
I disagree with the majority’s view that the evidence of causation, is legally sufficient to support the jury’s finding that appellee’s injuries were proximately caused by the negligence of appellant. Therefore, I respectfully dissent.
As noted by the majority, a plaintiff in the posture of appellee must plead and prove that the defendant’s negligence1 proximately caused the injury in order to recover. Leitch v. Hornsby, 935 S.W.2d 114, 118 (Tex.1996). Proximate cause consists of cause in fact and foreseeability. Id. Cause in fact means that the alleged negligent act or omission was a substantial factor in bringing about the injury and without which the injury would not have occurred. El Chico Corp. v. Poole, 732 S.W.2d 306, 313 (Tex.1987). Cause in fact may not be established by mere guess or conjecture; it must be proven by competent evidence. Hamer v. E-Z Mart Stores, Inc., 825 S.W.2d 456, 463 (Tex. 1992).
Appellee worked 17 years for appellant doing physically demanding work. His job required a great deal of lifting and carrying until approximately 1992, when under provisions of a union contract, he bid for the job and became operator of a cryovac machine. His job at the cryovac machine did not require such heavy lifting and carrying as he had previously done, but it required him to constantly bend, reach to grasp bags of processed beef product, and adjust and position the bags on the cryo-vac machine.
Appellee worked as a cryovac operator from 1992 until April 29, 1995. For approximately two weeks before April 29th, he received treatments from the plant nurse because of discomfort in his hand and wrist. On April 29th, according to appellee, he reached the point that he was physically unable to do the work required by the cryovac machine position because of pain and limitations to his left hand, left wrist, and his neck. After April 29th, he worked about a week in a different job on light duty, using one hand. He then began experiencing pain in his leg which caused him to stop working altogether. Dr. Mark Scioli, who performed surgery on appellee, testified that appellee sustained cumulative trauma disorder (CTD) injuries to his hand, neck and low back which were caused by the repetitive movements and physical stresses of his work activities. Dr. Scioli did not, however, testify that appellee’s injuries would have been avoided if the cryovac job activities had been reduced or the workplace design had been altered before appellee was injured so as to correct the activities and designs on which appellee based his negligence claim.
Appellee did not plead or undertake to prove that the cryovac machine job in its entirety was unsafe and that appellant was negligent in simply having a cryovac operator position at all. There was no attempt to show that all repetitive bending, reaching, grasping, pulling and lifting movements would have been removed from the cryovac operator’s job if appellant had *703been acting with ordinary care. And, as shown by appellee’s proof, a CTD injury is the end result of repetitive physical movements and stresses which individually are not so great as to cause an injury, but, rather, which eventually cumulate to “wear out” a part of the injured person’s body and thereby cause what is referred to as a CTD injury.
Appellee’s allegations of negligence and proof were, in substance, that appellant was negligent and provided an unsafe place to work because the machinery and design of the cryovac operator’s workplace required excessive bending, reaching, pulling and body movements, without appropriate rest periods, and also because appellant did not timely detect and cause treatment of appellee’s CTD symptoms. Appellee alleged that the cryovac operator’s job as it was prior to and in April, 1995, required appellee to bend his body too far, reach too far for the bags of product, process too many bags of product (ie., the product processing line was set at a chain speed which was excessive) and work for excessive periods without rest breaks. He also alleged that the machine did not have a photo-electric eye to automatically stop the processing conveyor line when appellee fell behind in moving bags of product, and appellant failed to do “symptom surveys” to detect early signs of CTD in appellee so the effects of the cumulative trauma could have been treated earlier.
Jury question number one inquired “Did the negligence, if any, of Excel proximately cause any injury in question?”2 The trial court instructed the jury that
“Proximate Cause” means that cause which, in a natural and continuous sequence, produces an event, and without which such cause such event would not have occwn'ed. In order to be a proximate cause, the act or omission complained of must be such that a person using ordinary care would have foreseen that the event, or some similar event, might reasonably result therefrom. (Emphasis added)
Neither party objected to the instruction. The jury answered “yes.”
Appellant urges that the jury’s answer to the question was based on legally insufficient evidence because there was no evidence that if either the cryovac machine worksite or job requirements had been modified or the number of cattle processed per hour had been reduced, or if all three had occurred, then appellee would not have suffered CTD injuries. See Leitch, 935 S.W.2d at 119. Appellant advances the same legal insufficiency argument as to its alleged negligence in failing to inquire about and detect appellee’s CTD symptoms earlier than appellee’s reporting of them. See id. Thus, appellant reasons, appellee has not proved that the alleged negligence of appellant was a cause in fact of appellee’s CTD injuries. In other words, appellee did not prove that but for the alleged negligence of appellant, appel-lee’s CTD injuries would not have occurred. See id.; Mosley v. Excel Corp., 109 F.3d 1006,1009 (5th Cir.1997).
As part of his proof, appellee introduced evidence about injury rates to cryovac operators; recommendations for changing the cryovac worksite, job activities and machinery configurations; and recommendations that CTD symptom surveys be performed. The recommended changes assertedly would have reduced the injury rate for cryovac machine operators. The *704evidence was not to the effect that CTD injuries would have been eliminated by the recommended changes.
Appellee’s evidence, however, did not address the “but for” aspect of appellee’s injuries having been proximately caused by appellant’s alleged negligence. For example, witnesses testified that the processing lines, including the cryovac machine operated by appellant, were set to process a certain number of cattle per hour. Ap-pellee testified that when he first began working at the cryovac machine in 1992, the processing rate was a little over 200 cattle per hour. The processing rate gradually increased. In April, 1995, when he last worked on the cryovac machine, he recalled that the processing rate was 240-250 per hour. Sometime after appellee quit working in 1995, the processing rate increased to 272 cattle per hour. Yet, no witness or evidence was presented to prove that if the processing rate had remained at 200 cattle per hour, or had been decreased instead of increased, appellee’s CTD injuries would not have occurred. Nor was evidence offered to prove that if the workplace had been modified before appellee was injured so that the angle he was required to bend, or the distance he was required to reach was reduced, then appellee would not have been injured. No proof was offered that use of an electric eye control on the product line would have prevented appellee’s back, shoulder, neck, wrist, or hand injuries. The proof was that installation of an electric eye control was considered and that recommendations (including a recommendation by OSHA) were made that such a control be installed. The changes purportedly would have, in general, reduced the number of injuries. Whether such changes would have prevented appellee’s particular CTD injuries was not addressed by the evidence.
Nor was evidence offered that appellee’s injuries would have been prevented had appellee received earlier treatment for his CTD symptoms. Moreover, evidence concerning early intervention by medical or other management when CTD symptoms occurred3 addressed the relieving, minimizing or curing of injuries following manifestation of the CTD’s, not prevention of the injury initially by removing the trauma which cumulated to cause the injury.
In sum, appellee did not prove that he would not have suffered his CTD injuries but for the alleged negligence of appellant. See El Chico Corp., 732 S.W.2d at 313. Whether his 17 years of physically demanding labor and repetitious activities required by the cryovac operator’s job which were not alleged to have been negligence on the part of appellant would have resulted in the CTD injuries to appellee even in the absence of the allegedly negligent acts and omissions of appellant was left to the speculation of the jury. In such instance, the proof of cause in fact is insufficient. Hamer, 825 S.W.2d at 463. I would sustain appellant’s second issue challenging the legal sufficiency of the evidence to support the jury finding that appellee’s injuries were proximately caused by the negligence of appellant.
. I assume the evidence is legally and factually sufficient to support a finding that appellant was negligent, and thus only address the issue of causation.
. Appellant’s fifth issue urges error in the broad form submission because of the three different parts of his body appellee claimed were injured. See Crown Life Ins. Co. v. Cas-teel, 22 S.W.3d 378, 388-90 (Tex.2000).
. The competency of such evidence was not challenged. See Leitch, 935 S.W.2d at 119.