The employee appeals the compensation judge’s finding that the employee’s May 26, 2004, personal injury was not a substantial contributing cause of his L2-3 herniated disc or the low back and leg symptoms resulting therefrom. We affirm.

Steven G. Gardner, the employee, has a significant history of low back symptoms and treatment. The compensation judge outlined, in a detailed finding, the employee’s chiropractic treatment at Grant Clinic between July 1987 and January 2004. (Finding 7.) The medical records reflect the employee was also seen at Kastner Chiropractic Clinic for low back pain and right leg numbness in December 2003 and in March 2004 for right-sided low back tightness without leg symptoms. In an unappealed finding, the compensation judge found the “employee’s chiropractic treatment records in evidence support his testimony that, over the years, he has sought out chiropractic care occasionally, usually after specific strenuous activities brought on his symptoms, that improved rapidly with a minor amount of chiropractic care, often a single office visit.” (Finding 8.)

In February 1992, the employee was seen by Dr. Gregg Dyste, a neurosurgeon. The doctor recorded a history of an onset of low back and right leg pain approximately three weeks previously with no known injury. The employee reported chiropractic manipulations gave him no relief. A CT scan showed a large disc herniation at L5-S1 on the right. Thereafter, Dr. Dyste performed a right L5-S1 hemilaminotomy and microdiscectomy. Following a healing period, the employee returned to his regular job without restrictions or ongoing symptoms.

The employee was seen at the Douglas County Hospital emergency room on January 24, 2002, complaining of a sudden onset of low back pain without radicular symptoms. A CT scan on January 25, 2002, showed bulging discs at L3-4, L4-5, and L5-S1, without focal protrusion and possible foraminal stenosis bilaterally at L5-S1.

The employee sustained an admitted personal injury to his low back on May 26, 2004, while working for Elbow Lake Coop Grain/Farmers Coop, the employer, insured by National Agribusiness Insurance Company. In the process of lifting a truck tire, the employee twisted and felt an immediate sharp pain in his low back. The injury happened in the presence of the employer’s general manager who told the employee to seek medical attention.

The employee saw Michael Kastner, D.C., on May 27, 2004, complaining of muscle spasm and difficulty standing straight. On examination, Dr. Kastner noted muscle tightness and pain at L5-S1 without radicular pain. The doctor diagnosed a lumbar strain with disc derangement and commenced chiropractic treatment. Dr. Kastner last treated the employee for L5-S1 symptoms on July 19, 2004.

The employee next sought treatment at Stevens Community Medical Center on November 5, 2004. The employee complained of low back pain radiating into his right leg and occasionally into the left leg with numbness and weakness in both legs. Dr. Bynum took the employee off work and referred him to Dr. Kim Tatsumi whom the employee saw on November 9. The employee told the doctor his symptoms had worsened over the last two months and Dr. Tatsumi recommended an MRI scan. The scan was not completed because the employee lacked health insurance at that time.

Following his personal injury, the employee continued working for the employer, with modified duties, until February 18, 2005, when he was terminated because the employer could no longer accommodate his physical restrictions. The employee then became eligible for health insurance through Minnesota Care.

An MRI scan performed in June 2005 showed a herniated disc at L2-3 with a free fragment impinging the thecal sac. Dr. Tatsumi then referred the employee to Dr. Thomas Falloon, a neurosurgeon, who saw the employee on August 1, 2005. The doctor obtained a history from the employee of low back surgery at L5-S1 twelve to thirteen years previously with occasional episodes of low back pain thereafter that responded to chiropractic care. The employee described his work injury and stated he treated conservatively because he was without health insurance. The doctor recommended surgery and later performed an L2-3 discectomy. Following surgery, the employee testified to a nearly complete resolution of his symptoms. The employee began working for Wal-Mart in February 2006, and has worked full-time since then.

Dr. John Dowdle examined the employee in October 2006 at the request of the employer and insurer. Dr. Dowdle reviewed the employee’s medical records, obtained a history from the employee, and performed a physical examination. The doctor diagnosed an acute disc herniation at L2-3 on the right, status post laminectomy and disc excision. The doctor opined the reports of Dr. Kastner from May 27 through July 19, 2004, were not consistent with a right-sided L2-3 disc herniation. Rather, the doctor felt the employee’s then symptoms were consistent with an aggravation of the employee’s underlying degenerative disc disease. Dr. Dowdle stated a disc herniation at L2-3 would usually cause non-dermatomal, intermittent radicular pain but none was reported by the employee until November 2004. Accordingly, Dr. Dowdle opined the May 26, 2004, personal injury likely aggravated the employee’s underlying degenerative disc disease but did not cause the L2-3 disc herniation. The doctor maintained the injury was temporary and resolved within three to four months.

In January 2007, Dr. Falloon completed a Health Care Provider Report in which the doctor opined the employee’s right-sided L2-3 disc herniation was caused by lifting a tire at work on May 26, 2004. The doctor indicated there was no evidence of any pre-existing condition that affected the employee’s disability. Dr. Falloon provided an 11% whole body disability rating and assigned work restrictions.

The employee filed a claim petition seeking workers’ compensation benefits. Following a hearing, the compensation judge found Dr. Falloon’s causal relationship opinion lacked foundation and adopted Dr. Dowdle’s opinion that the May 2004 injury was not a substantial contributing factor to the employee’s herniated disc at L2-3. The employee appeals.

The determinative issue in this case was whether the employee’s admitted personal injury on May 26, 2004, was a temporary injury to the low back as asserted by Dr. Dowdle, or whether the injury was a substantial contributing cause of the employee’s L2-3 herniated disc as opined by Dr. Falloon. The compensation judge rejected Dr. Falloon’s causation opinion, finding the opinion lacked foundation because the doctor did not put the employee’s symptoms from and after November 2004 in the context of his many year history of low back and leg symptoms. Citing Welton v. Fireside Foster Inn, 426 N.W.2d 883, 41 W.C.D. 109 (Minn. 1988), the compensation judge stated a doctor’s opinion without explanation is insufficient to support a finding of liability for a work injury. We disagree.

In Welton, the Minnesota Supreme Court upheld, on substantial evidence grounds, a compensation judge’s finding that the employee did not have a compensable low back injury. The court observed neither the employee’s testimony nor the medical records evidenced any connection between the employee’s 1981 work-related shoulder and left knee injury and the employee’s low back condition in 1984, reiterating that an expert opinion must be based on an adequate factual foundation. We do not, as the compensation judge did, read the Welton case as requiring a medical expert to provide an explanation for his or her opinion.

Foundation goes to the competency of a witness to provide an expert opinion. The competency of a medical expert depends both upon the witness’s scientific knowledge and his or her practical experience with the subject matter at issue. Drews v. Kohl’s, 55 W.C.D. 33, 39 (W.C.C.A. 1996) (citing Reinhardt v. Colton, 337 N.W.2d 88, 93 (Minn. 1983)). Dr. Falloon is a neurosurgeon and the employee’s treating doctor. The doctor took a history from the employee, reviewed the employee’s MRI scan, personally examined the employee, and provided treatment to the employee for his back condition. As a general rule, this level of knowledge establishes a doctor’s competence to render an expert opinion. See Grunst v. Immanuel-St. Joseph Hosp., 424 N.W.2d 66, 68, 40 W.C.D. 1130, 1132-33 (Minn. 1988).

While Dr. Falloon’s review of the employee’s prior treatment records may have been limited, we have stated previously that such a failure does not necessarily render a doctor’s opinion without foundation. Drews, id.; Young v. Fairview-Univ. Med. Ctr., No. WC04-108 (W.C.C.A. July 28, 2004). Similarly, a failure to explain the mechanism of the injury or the underlying reasons for the opinion may go to the persuasiveness or weight that may be afforded the opinion by the compensation judge, but does not render the opinion without foundation. See, e.g., Goss v. Ford Motor Co., 55 W.C.D. 316 (W.C.C.A. 1996); Simons v. Ridgeview Med. Ctr., No. WC06-211 (Dec. 1, 2006); Midtling v. Schwan’s Sales Enters., slip op. (W.C.C.A. Sept. 22, 2003); Darnick v. Swett & Crawford, slip op. (W.C.C.A. Oct. 29, 2002). We, accordingly, conclude there was adequate foundation for Dr. Falloon’s opinion.

We, nonetheless, affirm the compensation judge’s findings. Resolution of conflicting medical expert opinion is the responsibility of the compensation judge, and the trier of fact’s choice between medical experts must be upheld so long as there is adequate factual foundation for the opinion accepted by the judge. See Nord v. City of Cook, 360 N.W.2d 337, 37 W.C.D. 364 (Minn. 1985). Here, the compensation judge specifically accepted the opinion of Dr. Dowdle. It is clear from the compensation judge’s findings that she reviewed and weighed the medical opinions in the context of the employee’s testimony and medical records, and found Dr. Dowdle’s causation opinion more persuasive than that of Dr. Falloon. The evidence as a whole adequately supports the facts assumed by Dr. Dowdle in rendering his opinion, and the compensation judge did not err in relying on Dr. Dowdle’s opinion that the May 26, 2004, injury was not a substantial contributing cause of the employee’s L2-3 disc herniation. We must, therefore, affirm.