physician and forensic pathologist Frederick Zugibe studied the likely circumstances of the death of Jesus in great detail. Zugibe carried out a number of experiments over several years to test his theories while he was a medical examiner. These studies included experiments in which volunteers with specific weights were hanging at specific angles and the amount of pull on each hand was measured, in cases where the feet were also secured or not. In these cases the amount of pull and the corresponding pain was found to be significant. Pierre Barbet, a French physician, and the chief surgeon at Saint Joseph's Hospital in Paris, hypothesized that Jesus relaxed his muscles to obtain enough air to utter his last words, in the face of exhaustion asphyxia. Some of Barbet's theories, e.g., location of nails, are disputed by Zugibe. Orthopedic surgeon Keith Maxwell not only analyzed the medical aspects of the crucifixion, but also looked back at how Jesus could have carried the cross all the way along Via Dolorosa. In an article for the Catholic Medical Association, Phillip Bishop and physiologist Brian Church suggested a new theory based on suspension trauma. In 2003, historians FP Retief and L. Cilliers reviewed the history and pathology of crucifixion as performed by the Romans and suggested that the cause of death was often a combination of factors. They also state that Roman guards were prohibited from leaving the scene until death had occurred. Theological significance Christians believe that Jesus' death was instrumental in restoring humankind to relationship with God. Christians believe that through Jesus' death and resurrection people are reunited with God and receive new joy and power in this life as well as eternal life. Thus the crucifixion of Jesus along with his resurrection restores access to a vibrant experience of God's presence, love and grace as well as the confidence of eternal life. Christology The accounts of the crucifixion and subsequent resurrection of Jesus provide a rich background for Christological analysis, from the canonical Gospels to the Pauline epistles. Christians believe Jesus' suffering was foretold in the Old Testament, such as in Psalm 22, and Isaiah 53 prophecy of the suffering servant. In Johannine "agent Christology" the submission of Jesus to crucifixion is a sacrifice made as an agent of God or servant of God, for the sake of eventual victory. This builds on the salvific theme of the Gospel of John