This chapter focuses on one of the main issues for augmented human engineering: integrating the biological user's needs in its methodology for designing human-artefact systems integration requirements and specifications. To take into account biological, anatomical and physiological requirements we need a validated theoretical framework. We explain how to ground augmented human engineering on the Chauvet mathematical theory of integrative physiology as a fundamental framework for human system integration and augmented human design. We propose to validate and assess augmented human domain engineering models and prototypes by experimental neurophysiology.