Characterization of the pierce two-node model under exercise load by parameter optimization toward construction of a modified thermal model for persons with spinal cord injury.

In this study, we attempted to develop a thermal model for estimating a body temperature in persons with spinal cord injury (SCI) during exercise. To clarify requisites for the SCI thermal model, we compared actual body temperature of SCI subjects with that calculated with a standard thermal model, that is, the Pierce two-node model. Model optimization by the parameter search method was able to fit the model-estimated skin and core temperature with those in able-bodied subjects during repeated exercise and rest. However, there remained a phase shift between actual and model-estimated core temperature trends in SCI subjects even after the optimization. The comparison of the optimized parameter combinations revealed that the Pierce two-node model was able to express loss of sweating in the SCI subjects, but unable to express delay in heat accumulation and dissipation. These results suggest that SCI thermal model requires additional nodes that express the speed and extent of heat transfer in the body of SCI persons.