ory arrest because of damage to the nerve fiber that controls the diaphragm. Such a situation may end in death before the administration of emergency medical support. [Table 5](#tbl_005){ref-type="table"}Table 5.Relationship between head acceleration and tolerance value shows horizontal force, vertical force, and moment calculated using the experimental data. Neck injury criteria are obtained from the applicant examination administered through static tests on the tolerance limits of the human neck and through dynamic impact tests on the probability of heavy injury (cadavers were used for these tests). The horizontal and vertical force are calculated by multiplying each direction of head acceleration (measured at the center of gravity) by a head mass 5 kg. The moment values are calculated by multiplying the calculated force by the length spanning the edge of the neck to the head's center of gravity. The comparison of neck tolerance values and experimental values for the body belts indicates a high possibility of the serious neck injury because the neck tolerance values for two individuals were both 1,100 N and the experimental tension values all exceeded 1,100 N. The tension values derived during the experiments on the full-harness dummy were all less than 1,100 N; the pressure derived from the experiment on F-NN-0 (no shock absorber) was close to 1,100 N. The vertical forces acting on the dummy equipped with a shock absorber were half the tolerance limit. Thus serious neck injury due to vertical force can be avoided through the use of shock absorbers. In addition, the horizontal force strongly depended on the type of safety belts and the use of shock absorbers. In the same situation, the maximum horizontal values can exceed the human tolerance limit when a body belt or a basic lanyard without a shock absorber is used. Moreover, the probability of neck injury can be attributed to anteflexion, regardless of whether a full harness or shock-absorber is used ([Table 5](#tbl_005){ref-type="table"}). A necessary measu