OPINION OF THE COURT
GREENBERG, Circuit Judge.This matter presents First and Fourteenth Amendment challenges to a regulation effective at Trenton State Prison, and is before the court on appeal from a final judgment entered in the district court following a nonjury trial. The parties state and we agree that the appeal involves application of the decision of the Supreme Court in O’Lone v. Shabazz, — U.S. -, 107 S.Ct. 2400, 96 L.Ed.2d 282 (1987), to essentially undisputed facts. Thus, we review the matter independently and may substitute our own judgment for that of the trial court. See D & G Equipment Co. v. First National Bank, 764 F.2d 950, 954 (3d Cir.1985). To the extent, however, that the district judge made findings on disputed issues of fact our standard of review is whether there is sufficient evidence in the record to support those findings. Fed. R.Civ.P. 52(a); Leeper v. United States, 756 F.2d 300, 308 (3d Cir.1985).
I.
A.
The facts are as follows. In 1981 plaintiffs Anthony Cooper, Abdur-Rahim Farrakhan, Conrad Corley, Rodney Daniels and Robert Stevens, members of the Nation of Islam, were prisoners sent to the Trenton State Prison from other penal institutions.1 The type of inmate at Trenton State, the only fully maximum custodial institution of the New Jersey Prison System, is demonstrated by the percent serving sentences for murder, rape, assault or robbery in 1981 which was respectively 45, 7, 8 and 24. Plaintiffs were all confined to the management control unit (MCU), a close custody area where prisoners identified as threats to internal security were segregated from the general prison population. The MCU was established following a violent confrontation in 1975 between two rival groups of Muslim prisoners in which one inmate was killed and several were very seriously injured. Inasmuch as the MCU is designed to prevent problems, including violence and disorder, assignment to it is determined on the bases of prior criminal activity, institutional adjustment, psychological reports, staff observations and confidential sources. Thus, the inmates in the MCU represent a significant threat to the safety and orderly operation of the prison. Although inmates are not transferred to the MCU without a hearing, it is not a punitive unit and therefore its purpose differs from that of a disciplinary segregation facility.
Through tight control of the MCU, the prison authorities prevent problem inmates from becoming catalysts to violence, disorder and escape. Congregate activities including religious services are extremely limited in the MCU as they are inconsistent with the unit’s objectives of containing and neutralizing the conspiratorial interests of inmates assigned there. Some inmates are *127assigned to the MCU even though their records are relatively good because the authorities view them as sophisticated operators who work through intermediaries and thus pose a significant threat to internal security. Significantly, none of the plaintiffs suggests that his assignments to the Trenton State Prison and the MCU were in any way inappropriate.
By any standard the inmates in the MCU are tightly controlled. They are confined to their cells for the entire day, including meal times, except for a one hour and ten minute exercise period in an enclosed yard measuring 20 feet by 80 feet. Inmates in the MCU receive double escort. Only 20 to 25 inmates are present in the yard when it is in use. At the times material to this case there were less than 30 inmates in the MCU.
B.
The Nation of Islam, to which plaintiffs belong, is based on the Koran as interpreted by Elijah Muhammad and ministers within the Nation. While the Nation recognizes the validity of individual prayer, it considers group prayer more significant as it reflects the cooperative nature of the religion. Plaintiff Cooper was recognized as an Imam or spiritual leader by the other plaintiffs. The prison authorities, however, do not recognize him in that capacity in the MCU. The Nation has a hierarchy with ranks such as captain, lieutenant and secretary.
In May 1981 plaintiffs were charged in a disciplinary proceeding with violating an administrative regulation barring group demonstrations when they engaged in a group prayer called a “Du’a,” during which they stood in a circle for a few minutes. They were acquitted of these charges. Subsequently, the regulation was amended to provide that:
Inmates are forbidden in any area of the institution to engage in any unauthorized group activity such as an:
a. Educational activity conducted without Education Staff supervision;
b. Sports activity conducted without Recreation Department of Custody Staff Supervision;
c. Religious activity conducted without Chaplaincy Department supervision.
Thus, the amended regulation prohibited group inmate activity conducted without supervision of the prison’s authorities.
Notwithstanding the adoption of the amendment, plaintiffs continued to engage in the Du’a in the yard without authorization and without requesting the supervision of the Chaplaincy Department. When plaintiffs were engaged in the Du’a other inmates stood around watching and were inactive.
Because they violated the amended regulation, disciplinary charges were again filed against plaintiffs and all received sanctions ranging from the loss of privileges to loss of commutation credits. Plaintiffs make no challenge to these disciplinary findings and, insofar as appears from the record, did not appeal them to the New Jersey courts.
Plaintiffs subsequently brought three separate actions, later consolidated, in the district court charging that the defendants, the prison authorities, had infringed their rights to exercise their religion freely under the First Amendment and had denied them equal protection of the laws under the Fourteenth Amendment.2 Plaintiffs then moved for an interlocutory injunction while defendants moved for summary judgment. Both motions were denied. Following a nonjury trial, the trial judge, Judge Bissell, reserved decision pending the decision of the Supreme Court on the appeal from our decision in Shabazz v. O’Lone, 782 F.2d 416 (3d Cir.1986). On June 9, 1987 the Supreme Court reversed our decision. — U.S. -, 107 S.Ct. 2400, 96 L.Ed.2d 282. Judge Bissell then filed a comprehensive but unreported opinion ruling in favor of defendants and on October *12813, 1987 a judgment was entered dismissing plaintiffs’ claims. This appeal followed.
C.
In his opinion Judge Bissell pointed out that the Nation of Islam places high significance upon congregate prayer believing it should be conducted whenever fellow-believers come together. He found that Cooper was recognized as the Imam, or leader, by the other plaintiffs in their prayers and religious activities; nevertheless he concluded that defendants’ refusal to allow plaintiffs to engage “in congregate religious activity in the MCU recreation yard is reasonable and permissible” under O’Lone as MCU inmates are dangerous and potentially disruptive persons who tend to invite and provoke inappropriate conduct in others and are capable of undermining the essential authority of prison administrators and correction officers. The judge also found that “repeated rituals by a particular affinity group may well cause factionalism, derision, counter ‘demonstrations’, complaints, demands for similar status, or physical reactions either in the yard or the cell block.” He also noted that plaintiffs had “reasonable opportunities to exercise their religion consistent with the security status” of the MCU as they could pray privately, receive individual visits from an authorized Imam, though he was not from the Nation of Islam, read religious materials, be given substitute food for pork, and observe fasting periods. Overall, he concluded that the regulatory scheme was reasonably related to legitimate penological interests at the MCU.
Judge Bissell rejected plaintiffs’ argument that the regulation was not uniformly enforced within the yard thus depriving plaintiffs of equal protection of the laws. He found that while basketball games, boxing matches and card games took place in the yard, they were authorized activities conducted in accordance with the challenged regulation as the equipment for these events was either supplied or permitted to be used by the staff and the events were supervised. The judge found there was no evidence that plaintiffs were treated differently from other religious groups.
II.
A.
Our starting point in the resolution of this case is, of course, O’Lone v. Estate of Shabazz, — U.S. -, 107 S.Ct. 2400, 96 L.Ed.2d 282. O’Lone involved a challenge to policies adopted by prison officials which resulted in the plaintiffs, members of the Islamic faith, being unable to attend Jumu’ah, a weekly Muslim congregational service, because their work assignments placed them outside the building in which the services were conducted and prison policies precluded them from returning except for emergencies. The Supreme Court upheld the policies.
In O’Lone the Supreme Court pointed out that convicted prisoners do not forfeit all constitutional protections by reason of their conviction and confinement including those under the First Amendment involving the free exercise of religion. — U.S. at -, 107 S.Ct. at 2404. It noted, however, that lawful incarceration brings about the withdrawal or limitation of privileges and rights for various reasons including institutional security. Thus it held, citing Turner v. Safley, — U.S. -, 107 S.Ct. 2254, 96 L.Ed.2d 64 (1987), that prison regulations alleged to infringe constitutional rights are judged under a “reasonableness” test less restrictive than that ordinarily applied to alleged infringements of fundamental constitutional rights. Therefore a prison regulation impinging on inmates’ constitutional rights is valid if reasonably related to legitimate penological interests. — U.S. at -, 107 S.Ct. at 2404. Accordingly, when such a regulation is challenged, prison officials need not prove that no reasonable method exists by which the inmates’ rights can be accommodated without creating bona fide security problems. Ibid.
The O’Lone court also made reference to specific factors set forth in Turner v. Safley relevant in a determination of the reasonableness of a challenged regulation. O’Lone, — U.S. at -, 107 S.Ct. at 2405-*12907. These include whether there is a valid, rational connection between the regulation and the legitimate governmental interest put forward to justify it, whether there are alternative means of exercising the right that remain open to prison inmates, what impact accommodation of the asserted constitutional right will have on guards and other inmates and on the allocation of prison resources generally, and whether ready alternatives exist for accommodating the prisoners’ right at de minimis costs to valid penological interests. Turner v. Safley, — U.S. at -, 107 S.Ct. at 2262. See also Monmouth County Corr. Inst. Inmates v. Lanzaro, 834 F.2d 326, 331-33 (3d Cir.1987), cert. denied, — U.S. -, 108 S.Ct. 1731, 100 L.Ed.2d 195 (1988).
B.
We have no difficulty sustaining the regulation against the above tests. Cooper was recognized by the other plaintiffs as the Imam or leader, a status Cooper also claimed for himself. Further, the Nation of Islam established a hierarchy with positions assigned to members. Therefore what plaintiffs did was to establish a leadership structure within the prison alternative to that provided by the lawful authorities and contrary to the very purposes of the MCU. Under this alternative authority structure, plaintiffs proposed to engage in daily group activity, and therefore set themselves apart from the other inmates as an affinity group and made the group’s existence obvious to other inmates and prison officials. Such a structure posed a potential threat to prison authority that caused reasonable concern among defendants. Therefore, there was a valid, rational connection between the regulation and the legitimate governmental interest put forward to justify it.
In reaching this conclusion we do not deal in abstractions and would have to disregard facts established beyond dispute to conclude that the concerns of the prison authorities which led to adoption of the regulation and the proceedings against plaintiffs were not reasonable. While plaintiffs invoke the highest principles of our law, they are dangerous persons who even among inmates convicted of the most serious offenses were singled out for special security treatment. For example, Cooper testified that he was serving a 14 to 15 year sentence for armed robbery and had prior convictions for armed robbery, bank larceny, possession of narcotics and breaking and entering. Although he has been a minister since 1971 he explained that periodically he has been suspended for behavior unbecoming to a Muslim and to a Muslim minister. Unquestionably plaintiffs’ confinement to Trenton State Prison and their assignment to the MCU demonstrate that while they are here relying on the law to seek their ends, they have not hesitated to turn against others in violation of the law. Clearly, there is a valid, rational reason for not permitting plaintiffs to establish an infrastructure within the MCU and have it openly function merely because plaintiffs claim a right to engage in their activities on the basis of their religion. See O’Lone v. Estate of Shabazz, — U.S. -, 107 S.Ct. at 2406.
The inquiry of whether there are alternative means of permitting plaintiffs to exercise their rights is dependent on how the affected right is defined. If exercise of that right means that plaintiffs must be able to carry out their particular unsupervised group activity, then it cannot be accommodated. But if the right is more broadly understood to include, as we think it should, general religious activity, see Monmouth County Corr. Inst. Inmates, 834 F.2d at 338-39, then there are alternative means of permitting plaintiffs to exercise it. Certainly a person is always free to pray individually. Further, plaintiffs may receive visits from an Imam, read religious materials, including the Koran, be given food consistent with their religion and observe religious holidays such as Ramadan. In this regard it must be recognized that while Muslims place great importance on group prayer, individual prayer is acceptable and a Muslim will receive blessings from individual prayer. The validity of individual prayer in prison situations is demonstrated by the uncontradicted testimony of a qualified Imam that a person incarcer*130ated by reason of his own acts is required to follow the restrictions attributable to his status. Here the restrictions included limitations on group prayer. Finally, we note that under the regulation supervised congregate religious activity is an alternative means for MCU inmates to engage in religious expression, albeit one in which the plaintiffs have disavowed any interest.
Turner v. Safley also indicated that in considering the reasonableness of a regulation a court should take into account how accommodation of the right will impact on other inmates and guards and on the allocation of prison resources generally. This consideration, of course, has both narrow and broad aspects. The impact may be measured at the immediate time when plaintiffs engaged in the prayer. If so there obviously was some impact as other inmates in the yard became completely inactive during that time. While we do not know whether this was from fear, respect or some other reason, we do know that the other inmates were affected.
But more significant than the immediate impact are the broader implications of plaintiffs’ activities. As we have indicated, the very purpose of the MCU was to restrict and closely supervise organized inmate activity. Plaintiffs’ conduct suggested to other inmates that an organized, unsupervised group could function within the prison.
Finally, Turner v. Safley indicated that the absence of ready alternatives to accommodate inmates’ rights is evidence of the reasonableness of a prison regulation while the rejection of ready alternatives permitting accommodation at de minimis cost to valid penological interests is evidence that a regulation is unreasonable. Inasmuch as the right claimed by plaintiffs was to function openly as an unsupervised group, there were no alternatives consistent with the concept of the MCU to accommodate it. See Monmouth County Corr. Inst. Inmates, 834 F.2d at 345.
C.
Plaintiffs also make a Fourteenth Amendment equal protection argument. They point out that “other more violent group activity, such as boxing matches and basketball games, which presented a greater security threat, was permitted in the yard.” Thus, in plaintiffs’ view, defendants’ response to plaintiffs’ activities was exaggerated. They further indicate that inmates could discuss controversial subjects including religious topics and that other religious groups could engage in activities within the MCU yard.
We reject these contentions for several reasons. First, the recreation activities to which plaintiffs point were authorized. Second, there is a fundamental difference between sporting events and informal discussions of controversial topics on the one hand and the existence of an organized, functioning alternative authority structure among inmates on the other. Third, the challenged regulation makes no distinction based on the religious group or sect. Finally, Elijah Tard, who was superintendent at Trenton State Prison during the time of the infractions here, testified that other religious groups did not engage in unsupervised group activities in the MCU yard. Thus, Judge Bissell’s finding that plaintiffs were not the victims of discrimination is fully supported.
We also point out that this case does not involve any claim by plaintiffs that they unsuccessfully requested Chaplaincy Department supervision for the Du’a. Rather plaintiffs conducted their activities on their own. Thus, we are not faced with a situation in which one religious group could obtain authorization for its services but another could not.
III.
The judgment of October 13,1987 will be affirmed.
. William Stovall was also a plaintiff in the trial court and he is listed as an appellant on the notice of appeal. However, in appellants' brief they state that he "does not join this appeal.” It further appears that he was not disciplined by the prison authorities for violation of the regulation challenged in this case and thus even the trial judge indicated that he might not have standing in the case. In the circumstances the appeal will be dismissed as to him and our references to "plaintiffs” shall not include him.
. Plaintiffs asserted a right to relief on other bases including the New Jersey constitution. In their brief on this appeal, however, they claim a right to relief only on the bases of the First and Fourteenth Amendments. Thus we consider their other contentions abandoned.