Active-Q: validation of the web-based physical activity questionnaire using doubly labeled water.

Increased use of the internet provides new opportunities for collecting data in large studies. the aim of our new web-based questionnaire,active-q,is to assess total physical activity and inactivity in adults. active-q assesses habitual activity during the past year via questions in four different domains: (1) daily occupation,(2) transportation to and from daily occupation,(3) leisure time activities,and (4) sporting activities. the objective of our study is to validate active-q's energy expenditure estimates using the doubly labeled water (dlw) method,and to assess the reproducibility of active-q by comparing the results of the questionnaire completed by the same group on two occasions. the validity and reproducibility of active-q were assessed in a group of 37 individuals,aged 20 to 65 years. active-q was distributed via email to the participants. the total energy expenditure of the participants was assessed using dlw for 11 consecutive days. the median time to complete active-q was 6.1 minutes. the majority of participants (27/37,73%) reported that the questionnaire was easy or very easy to answer. on average,active-q overestimated the total daily energy expenditure by 440 kj compared with the dlw. the spearman correlation between the two methods was r = 0.52 (p < .001). the intraclass correlation coefficient for total energy expenditure between the results of active-q completed on two occasions was 0.83 (95% ci 0.73-0.93). active-q is a valid and reproducible method of assessing total energy expenditure. it is also a user-friendly method and suitable for web-based data collection in large epidemiological studies.