This appeal is before this court for a second time. Appellee Gregg Agricultural Enterprises (hereinafter Gregg Farms) originally appealed a finding by the Commission that the appellant, Alvin Ray White, was entitled to a permanent anatomical rating of 26 percent. In the first appeal, we held that we could not reach the merits of White’s argument because the Commission had failed to make sufficient findings of fact in support of its conclusion. We remanded with directions to the Commission to include an explanation of why it disregarded White’s previous injury in Texas and its effect on White’s current disability. See Doug Gregg Farms v. Alvin R. White, CA97-1424 slip op., (Ark. App. May 27, 1998). Following our remand, the administrative law judge rendered findings and reached the same result. The law judge found that White’s 13 percent impairment to the body as a whole, in combination with his 14 percent loss of cervical range of motion, resulted in a 26 percent disability to the body as a whole. Gregg again appealed to the full Commission. The Commission then considered at length the medical evidence relating to the Texas injury and concluded that White had not proven that he sustained any new loss of cervical motion, instead of the 14 percent, *313and that he had sustained only an additional 2 percent impairment rating (instead of 13 percent). White brings this appeal.
This case had been the subject of two hearings before the administrative law judge. The first hearing involved only the issues of compensability and temporary total disability. At the hearing on those issues, White testified that his first workers’ compensation injury, a pinched nerve in his shoulder, occurred in 1978, while he was working as a heavy-duty mechanic in Texas, and that he suffered another compensable injury to his back in November 1988. The 1988 injury led to a fusion surgery at C5-6, C6r-7 in 1989. White testified that he settled his claim for workers’ compensation for approximately $45,000. On cross-examination, he denied being told by his treating physician for the 1988 injury, Dr. Stockton, that he was precluded from returning to work.
White began working part time for Gregg Farms in October 1991, at first on a part-time basis to see if he could handle the work. In February 1992, he began working full time. He testified that the job included a lot of bending and stooping. He said that prior to working for Gregg Farms, he was not having any trouble with his neck nor was he on any medication. On cross-examination, he testified that he saw a doctor approximately eight months before going to work for Gregg Farms. He also stated that he had attempted to see a doctor for follow up from his surgery, but could not get the paperwork from Texas straightened out in order to do so. He said that he began to experiencé pain, similar to pain he had experienced from his previous injuries, in December 1992, and he would occasionally wear a neck brace, which had been prescribed for him after his neck injury in 1988. He presented to Dr. Foster in April 1993. He stated that Dr. Foster’s office billed his Texas compensation carrier for some of the bills. He said he worked at Gregg Farms until approximately two weeks before he had surgery in June 1993. After his surgery, Dr. Foster assigned White a 13 percent impairment rating. White also testified that Dr. Foster considered it to be a new injury. White ’ testified that his fusion surgery was successful, and he returned to fight-duty work for Gregg Farms on December 17, 1993, and worked a little more than one month before he was terminated. He applied for temporary total disability and medical benefits from May 25, 1993 through December 17, 1993. Gregg Farms denied all liability.
*314Doug Gregg, owner of Doug Gregg Farms, testified that when he hired White in late 1991, he was aware of White’s back and neck problems. He said that White began to complain about pain in his back and neck shortly after he began working full-time, and that White attributed the pain to a previous injury. He also stated that he remembered White wearing a neck brace shortly after he began working full time, in the spring of 1993. Gregg testified that at no time did White ever report that he had sustained a work-related injury. The first time Gregg realized that White was claiming workers’ compensation benefits was when he received a letter from White’s attorney. In that letter, White’s attorney wrote: “At the time of the injury, Alvin Ray White was working on a truck on a creeper straining with a bar and injured his back. Copy of the letter from the orthopedic surgeon confirming a compensable injury is attached.” The description of the injury matched the injury White received in Texas.
Gregg also testified that after he terminated White for leaving the job without notifying him or their immediate supervisor, White mentioned that he had fallen on the job and that he needed to fill out a workers’ compensation form in order to report the injury. Gregg argued that White was not entitled to such benefits because White’s injury was a recurrence of a previous injury for which he was compensated under Texas workers’ compensation law.
On March 25, 1994, the law judge issued an opinion in that case awarding White temporary total disability from May 25 until December 17, 1993, medical benefits, and attorney’s fees.
The law judge wrote:
Claimant testified that he was virtually asymptomatic when he went to work for Gregg and that his disabling condition came on gradually over time. I conclude that this is not a case where claimant remained symptomatic for a period of time following his first surgery and then sustained a recurrence of the initial injury. Dr. Foster’s testimony that claimant’s permanent impairment has increased by 13 percent is also evidence that claimant sustained a new injury or aggravation causing distinct, new, anatomical deficits rather than a simple recurrence of a previous condition.
*315Gregg appealed to the full Commission, and White cross-appealed. The Commission affirmed and adopted the law judge’s opinion, and this order was not further appealed by either party.
In a subsequent hearing, White sought compensation for permanent disability. At that hearing, the specific issue-was whether White was entitled to a permanent anatomical impairment rating, which is the issue of this appeal. Gregg denied liability for any of White’s anatomical impairment, arguing that “all anatomical impairment is a result of White’s preexisting or prior injury that occurred in 1988.”
At that hearing, White testified again to when he began working for Gregg Farms and when his aggravation started. He also testified to the complications experienced after his June 10, 1993, surgery, which included having trouble turning his neck and sitting for a long period of time. He stated that he has continual pain. He stated that despite his problems, he returned to work in June 1994 and is working full time at Micro Plastics in Flippin. On cross-examination, White denied informing one of his doctors that he had been in constant pain since his injury in 1988. White also denied seeing any medical reports that classified him as totally and permanently disabled as a result of the Texas injury.
Dr. Robert Foster testified in a deposition that he first saw White in April 1993. He said White presented to him, complaining of persistent neck pain, headaches, and occasional pain in his arms. Dr. Foster’s x-rays of White revealed pseudoarthrosis at C5-6. Dr. Foster attributed the fusion failure at C5-6 to White’s smoking and the fact that White underwent two-level fusion surgery, as opposed to a one level.
When asked if the job at Gregg Farms caused White’s pseudoarthrosis, Foster replied “No.” However, Foster also stated that if he had been White’s treating physician in Texas, he would have told White “that if you engage in any type of heavy work or activity, it may become symptomatic enough that you require surgery.” He also rated him with a 13 percent impairment rating representing his previous surgeries as well as his previous fusions. He stated that he would not have been able to give him an impairment rating after his surgery in Texas because, at that time, White was not medically maximized in that he did not completely fuse. *316He stated that the job at Gregg Farms made White symptomatic in that it caused him more pain, “[h]e had already stated that he had pain.” On May 27, 1996, Dr. Foster then included an additional 14 percent rating for loss of range of motion, making a combined anatomical rating of 26 percent.
The administrative law judge issued an opinion stating that White had proven by a preponderance of the evidence that he was entitled to a 26 percent permanent impairment rating as assigned by Dr. Foster. In addition, the law judge found that White had sustained a gradual onset injury while working for Gregg Farms.
Gregg Farms appealed to the full Commission, which affirmed and adopted the findings and the opinion of the law judge. Gregg Farms then appealed to this court, at which time this court remanded the case to the Commission, who in turn remanded it to the administrative law judge to make further findings of fact.
As stated above, upon remand, the administrative law judge again found that White had proven by a preponderance of the evidence that he was entitled to the 26 percent permanent impairment rating as assigned by Dr. Foster. The administrative law judge failed to make findings of fact regarding Dr. Stockton’s opinion that appellee was permanently and totally disabled due to the failure of the fusion at C5-6.
The Commission reversed the law judge. It agreed that White has experienced a gradual onset injury that resulted in disability in May 1993. It cited the medical records resulting from his Texas injury that stated that White could neither get and keep employment nor engage in any substantial gainful activity. It found that White had sustained a compensable aggravation of his preexisting injury, causing him to undergo a second fusion at the C5-6 level.
In addition, the Commission repeated that Dr. Foster had stated “unequivocally” in his deposition that the 13 percent anatomical impairment rating included everything that had been done to White, including the previous fusion surgery in 1989 as well as the re-fusion performed in 1993. It noted that the record reflected that the 13 percent anatomical impairment rating assigned by Dr. Foster was based upon and took into consideration White’s preexisting condition. Furthermore, as explained by Dr. Foster, 11 percent of the 13 percent was attributed to the original two-level *317fusion surgery made necessary by the Texas injury. Therefore, Dr. Foster only assigned, and the AMA Guidelines only allowed, an additional 2 percent impairment rating for the second surgical procedure to repeat the fusion that was required as a result of the compensable aggravation.
In addition, the Commission found that White had not proven by a preponderance of the evidence that he was entitled to a 14 percent permanent impairment rating for loss of range of motion. It found that although the record revealed that White did suffer a loss of range of motion after undergoing his first surgical procedure, there was insufficient evidence to determine the extent of his motion in his cervical spine prior to and subsequent to the 1993 repeated fusion. It did not dispute that White suffered a loss of range of motion, but found that it was unable to determine how much of that loss preexisted his compensable injury. Therefore, the Commission reversed the law judge’s award of 26 percent and awarded White a 2 percent impairment rating. White brings this appeal.
Law of the case
In the first hearing in this case, determining whether White had sustained a compensable injury in the course and scope of his employment, the administrative law judge made a factual finding that White had not remained symptomatic for a period of time following his first surgery and then sustained a recurrence of the initial injury. For his first point on appeal, White argues that that finding became the law of the case because it was affirmed and adopted and not appealed to this court. He argues that if the Commission is allowed to reverse itself after a final order — that being the order determining whether White was entitled to temporary total disability — it would give a party “two bites at the apple instead of just one.” We do not agree with this argument.
The issue of permanent impairment rating was never before the law judge at the first hearing. The only issue presented by White at that hearing concerned the issue of temporary total disability. In fact, White’s counsel stated to the law judge at the first hearing the issue being considered was that of temporary total disability and that the parties were not arguing the issue of permanent impairment rating.
*318Before the hearing on the issue of temporary total disability the following exchange took place:
Law JUDGE: ... Now, are we trying the permanent impairment or
Mr. SPENCER (attorney for White): No, Your Honor. Diane (counsel for Gregg) and I talked yesterday, and I wanted to add that as an issue, but Diane has some other things she had to do before that becomes an issue. This will probably clearly be Second Fund case since he did have a previous workers’ comp, injury.
Law Judge: Okay.
Mr. Spencer: However, you know, we are able to introduce by agreement the reports that were just received from Doctor Foster which indicates another 13 percent in addition to what he already had.
Res judicata applies where there has been a final adjudication on the merits of the issue by a court of competent jurisdiction on all matters litigated and those matters necessarily within the issue that might have been litigated. Castleberry v. Elite Lamp Company, 69 Ark. App. 359, 13 S.W.3d 211 (2000). The doctrine of res judicata is applicable to decisions by the Commission. Castleberry v. Elite Lamp Company, supra. The doctrine of res judicata applies only to final orders or adjudications. White v. Air Systems, Inc., 33 Ark. App. 56, 800 S.W.2d 726 (1990). The filing of a petition for review with the full Commission within thirty days prevents the order of the administrative law judge from becoming final. White v. Air Systems, supra. The key question regarding the application of res judicata is whether the party against whom the earlier decision is being asserted had a full and fair opportunity to litigate the issue in question. Castleberry v. Elite Lamp Company, supra.
Whatever is before the supreme court and disposed of in the exercise of its jurisdiction must be considered settled, and the lower court must carry that judgment into execution according to its mandate. Bussell v. Georgia Pacific Corp., 64 Ark. App. 194, 981 S.W.2d 98 (1998). The trial court, and by analogy the Commission, has no power to change or extend the mandate of the appellate court. Bussell v. Georgia, supra. In Bussell v. Georgia, we stated:
Whatever was before the Court, and is disposed of, is considered as finally settled. The inferior court is bound by the judgment *319or decree as the law of the case, and must carry it into execution according to the mandate. The inferior court cannot vary it, or judicially examine it for any other purpose than execution. It can give no other or further relief as to any matter decided by the Supreme Court even where there is error apparent; or in any manner intermeddle with it further than to execute the mandate and settle such matters as have been remanded, not adjudicated by the Supreme Court. ... The principles above stated are, we think, conclusively established by the authority of adjudged cases. And any further departure from them would inevitably mar the harmony of the whole judiciary system, bring its parts into conflict, and produce therein disorganization, disorder, and incalculable mischief and confusion. Besides, any rule allowing the inferior courts to disregard the adjudications of the Supreme Court, or to refuse or omit to carry them into execution would be repugnant to the principles established by the constitution, and therefore void.
64 Ark. App. at 199-200, 981 S.W.2d at 100 (quoting Fortenberry v. Frazier, 5 Ark. 200, 202 (1843)).
The Commission cannot change its findings of fact on remand. Lunsford v. Rich Mountain Elec. Coop., 38 Ark. App. 188, 832 S.W.2d 291 (1992). Matters decided on prior appeal are the law of the case and govern our actions on the present appeal to the extent that we would be bound by them even if we were now inclined to say that we were wrong in those decisions. Lunsford v. Rich Mountain Elec. Coop., supra. The supreme court has long adhered to the rule that when a case has been decided by it and, after remand, returned to it on a second appeal, nothing is before it for adjudication except those proceedings had subsequent to its mandate. Ouachita Hospital v. Marshall, 2 Ark. App. 273, 621 S.W.2d 7 (1991).
White seems to argue that the Commission and this court are bound by the findings made by the administrative law judge after the hearing on whether White had suffered a compensable injury. We disagree. What this court is reviewing is whether White is entitled to permanent disability benefits based upon an assigned anatomical impairment rating. That issue was not before the administrative law at the first hearing (and, thus, not before the Commission), and both parties agreed that the issue of any permanent impairment would be taken up at a later hearing. Furthermore, Dr. Foster’s deposition testimony in which he discussed how *320he arrived at White’s 13 percent anatomical impairment rating was not even taken until after the first hearing. It was not until after the 13 percent impairment rating was assigned and the deposition taken that Foster assigned an additional 14 percent impairment rating for loss of range of motion.
Further, we are not bound by the Commission’s findings in the first appeal to this court on the issue of permanent disability benefits because we instructed the Commission to take into account more testimony, testimony that we thought was relevant to the outcome of the case, that the Commission had not considered in making its original determination. In our remand, we told the Commission to consider White’s previous injury, his pain from that injury, and Dr. Stockton’s analysis of White’s condition. That is exactly what the Commission has done.
In addition, one of the factors to be considered in determining the applicability of the doctrine of res judicata is whether the party against whom the earlier decision is being asserted had a full and fair opportunity to litigate the issue in question. Castleberry v. Elite Lamp Company, supra. In the case at bar, the Second Injury Fund1 was not made a party to the case until the second hearing before the administrative law judge involving whether White was entitled to a permanent anatomical rating of 26 percent.
Substantial evidence
On appellate review, we view the evidence in the light most favorable to the findings of the Commission and give the testimony its strongest probative force in favor of the action of the Commission. Buford v. Standard Gravel Co., 68 Ark. App. 162, 5 S.W.3d 478 (1999). Our standard of review on appeal is whether the Commission’s decision is supported by substantial evidence. Buford v. Standard Gravel Co., supra. Substantial evidence is such relevant evidence as a reasonable mind might accept as adequate to support a conclusion. Buford v. Standard Gravel Co., supra. We do not reverse a decision of the Commission unless we are convinced *321that fair-minded persons with the same facts before them could not have arrived at the conclusion reached. Buford v. Standard Gravel Co., supra. In cases where the Commission’s denial of relief is based upon the claimant’s failure to prove entitlement by a preponderance of the evidence, the substantial-evidence standard of review requires us to affirm the Commission’s action if its opinion displays a substantial basis for the denial of relief. Moser v. Arkansas Lime. Co., 40 Ark. App. 108, 842 S.W.2d 456 (1992), supp. op. on denial of rehearing, 40 Ark. App. 108, 846 S.W.2d 188 (1993).
Questions concerning the credibility of witnesses and the weight to be given to their testimony are within the exclusive province of the Commission. Arkansas Dep’t of Health v. Williams, 43 Ark. App. 169, 863 S.W.2d 583 (1993). We defer to the Commission’s findings on what testimony it deems to be credible. Arkansas Dep’t of Health v. Williams, supra. When there are contradictions in the evidence, it is within the Commission’s province to reconcile conflicting evidence and to determine the true facts. Arkansas Dep’t of Health v. Williams, supra. The Commission is not required to believe the testimony of the claimant or any other witness, but may accept and translate into findings of fact only those portions of the testimony that it deems worthy of belief. Jordan v. Tyson Foods, Inc., 51 Ark. App. 100, 911 S.W.2d 593 (1995).
It is undisputed that White suffered a compensable injury in 1988 in Texas and that he underwent a two-level fusion at C5-6 and C6-7. It is also undisputed that the fusion at C5-6 did not succeed. In addition, there was testimony that Dr. Stockton, the treating physician in Texas, found that White was permanently and totally disabled. White went to work for Doug Gregg Farms in October 1991, and in December 1992, began experiencing pain. Both the Commission and the law judge relied upon Dr. Foster’s testimony that White suffered from pseudoarthrosis.
The Commission correctly noted that in his deposition testimony, Dr. Foster unequivocally explained that the 13 percent anatomical impairment rating included everything that had been done to the claimant, including his previous two-level fusion surgery in 1989 and the repeated fusion in 1993. In a letter to White’s attorney, Dr. Foster stated that based upon AMA Guidelines, White’s impairment rating was 13 percent to his cervical spine as a whole. Dr. Foster wrote, “This is based on an anatomical impair*322ment rating since the patient has had three spinal surgeries for this level.” As mentioned previously, 11 percent of the 13 percent was based upon and took into consideration White’s preexisting condition, and, therefore, the Commission determined that only 2 percent was attributable to White’s 1993 surgery, which was required as a result of the compensable aggravation he sustained from working at Doug Gregg Farms.
Even though Dr. Foster assigned White a 14 percent impairment rating to the cervical spine, he was unable to apportion this loss of range of motion to White’s 1989 two-level fusion surgery or the re-fusion surgery in 1993, or a combination of both. In fact, in his deposition testimony, he admitted that he never tested White in order to assign him a 14 percent impairment rating. The Commission found that White had suffered a loss of range of motion, but it simply said that White had not proven that the entire 14 percent was due to the aggravation he sustained from working at Doug Gregg Farms or the surgery in 1993 that the aggravation precipitated. It found that:
Dr. Foster merely arrived at the 14 percent functional impairment rating for loss of range of motion by comparing claimant’s post-surgical motion with that of a normal person.Therefore, it is mere speculation that the entire 14 percent resulted from claimant’s compensable injury. Without medical evidence establishing a baseline range of motion after claimant’s first surgical procedure, we cannot determine the extent, if any, of claimant’s loss of range of motion as a result of bis compensable injury.
Based upon the foregoing, we affirm.
Stroud, C.J., Robbins, and Neal, JJ., agree.
Roaf, J., concurs.
Griffen, J., dissents.