RESUMEN
OBJECTIVES: To develop a valid and reliable internet based lifestyle physical activity questionnaire suitable for use among the United Kingdom population. METHODS: After a detailed content analysis and item generation using a panel of experts, an internet based measure of lifestyle physical activity behaviour was developed. Data were collected from 1369 subjects in total. Confirmatory factor analysis was used to examine the two subscales of the Brunel lifestyle physical activity questionnaire among independent samples and by use of multisample analyses. RESULTS: The confirmatory factor analysis showed the psychometric integrity of two subscales: planned physical activity and unplanned physical activity. CONCLUSION: The questionnaire is a valid and reliable instrument designed to provide an online behavioural assessment to be used in conjunction with a 12 week personalised fitness programme delivered through the internet.