Purpose: To develop a model of the dynamics of functioning, disability and contextual factors which harmonises with the International Classification of Functioning, Disability and Health (ICF).
Method: Model parts based on ICF were identified and a model drawing from engineering concepts was developed. The conceptual and practical applicability of the model was discussed.
Results: The so called Friction Model was created, which incorporates the ICF entities capacity, performance, environmental factors, health condition, body functions and structures, and personal factors. Friction describes the interaction between a person and his or her environment. The coefficient of friction is defined as the ratio between capacity and performance.
Conclusion: Carrying conceptual strengths and limitations, the Friction Model appears to offer opportunities for practical applications, including ICF-based alternatives to health-economic analyses. Harmonising with the ICF model and terminology, the model uses friction to describe the interaction between a person and the environment. The coefficient of friction can be used as a simple measure of how facilitating an environment is. The applicability is not limited to functioning of people with impairments.