Validity and repeatability of the EPIC-Norfolk Physical Activity Questionnaire

Area of Science:

• Epidemiology
• Public Health
• Exercise Science

Background:

• Physical activity assessment is crucial for epidemiological studies but often inaccurate.
• The European Prospective Investigation into Cancer Study-Norfolk (EPIC-Norfolk) developed a comprehensive questionnaire for total energy expenditure.
• This study evaluates the questionnaire's repeatability and validity against objective measures.

Purpose of the Study:

• To assess the repeatability of the EPIC-Norfolk physical activity questionnaire.
• To determine the validity of the questionnaire against objective measures of fitness and energy expenditure.
• To establish the utility of the questionnaire for large-scale epidemiological research.

Main Methods:

• 173 participants underwent repeated heart-rate monitoring (4-day episodes) and sub-maximum oxygen uptake tests over 12 months.
• Physical activity was assessed using the questionnaire detailing home, work, and recreational activities over the past year.
• Repeatability was assessed in 399 participants completing the questionnaire twice over 3 months.

Main Results:

• A moderate correlation (r=0.28) was found between objective energy expenditure and reported activity.
• Reported vigorous activity correlated with cardio-respiratory fitness (r=0.16) and high energy expenditure periods (r=0.17).
• High repeatability (r=0.73) was observed for the sum of recreational and occupational activity.

Conclusions:

• The EPIC-Norfolk physical activity questionnaire demonstrates acceptable validity and repeatability.
• Its performance is comparable to other instruments used in major epidemiological studies.
• The questionnaire is a valuable tool for assessing physical activity in population-based research.