This report reviews ergonomic and biodymamic factors related to the introduction of head mounted loads for military land environments. It presents an overview of current knowledge pertaining to the assessment of head mounted load limits. Limitations in the predictive ability of existing modelling and measurement techniques are discussed. The report introduces a novel biodynamic model, currently umder development by DSTO, designed to overcome these limitations. LOD's Human Biodymamics Engine is a realistic model of the human body motion within a dynamic envirornment. The model is unprecedented in its representation of the full, distributed, three-dimensional neck and spine dynamics and in its incorporation of reflexive and cerebellar-like control of spinal motion. The model is used to investigate specific considerations of head mounted load design and their use in an operational context.