The demands imposed on the user during the Information Retrieval (IR) process are well-recognised, with numerous studies highlighting the influence and importance of cost, effort, and load in explaining user search behaviour and experience. Despite this understanding, there exists no universal definitions of these constructs or standardised methods of measuring them within the field of IR. As a result, an open research problem has emerged in relation to how these constructs have been defined, interpreted, and subsequently measured. To address this research problem, the aim of this research is two-fold. Firstly, to establish working definitions and a conceptual framework for defining cost, effort, and load; and secondly, to examine and evaluate existing measures of effort and load within an IR context.