Self-report methods can include physical activity records or logs, which require individuals to record every activity done over a predetermined period of observation. However, these methods are utilized less frequently in large populations and community-based studies due to the high associated staff and participant burden with completing and calculating summary estimates. As such, physical activity questionnaires will likely continue to be the primary self-report method used to estimate physical activity levels in research studies due to their low cost and relative ease of administration.
Physical activity questionnaires vary in their complexity, physical activity domain (e.g., leisure, occupational, transportation, activities of daily living), recall time frame (e.g., past 24-hours, week, month, year), mode of administration (i.e., interviewer- vs. self-administered), and characteristics of the targeted population (i.e., older adults, women, children). Physical activity questionnaires may also vary by study design in mind, with some developed to use for surveillance while others are sensitive to behavior change for use in intervention studies. Understanding the intended use and psychometric properties (i.e., test-retest reliability, validity, and sensitivity) of a physical activity questionnaire will help you identify which questionnaire is most appropriate for addressing your study questions. Further use of an appropriate measure will improve the overall precision of the physical activity estimate and enhance the ability to establish significant relationships between physical activity and the health-related outcomes of interest. It is important to note that failure to account for the psychometric properties of a physical activity questionnaire may increase the risk of non-differential misclassification which can weaken or eliminate association between physical activity and health outcomes.
Questionnaires vary in their complexity from a single global question about general physical activity level (i.e., low, moderate, and high active) to activity-specific questionnaires that inquire about physical activity done over an individual's lifetime. A simple questionnaire such as the Lipid Research Clinic physical activity questionnaire is one example of a global measure. With global questionnaires, participants are asked questions such as, "Thinking about the things you do at work, how would you rate yourself as to the amount of physical activity you get compared with others of your age and sex?" Global queries such as these can be used to crudely group individuals by their activity or inactivity status. On the other end of the complexity spectrum, activity-specific questionnaires or historical questionnaires such as the Historical version of the Modifiable Activity Questionnaire (MAQ) ask about participation (i.e., frequency and duration) in leisure activities over specific periods during an individual's lifetime.
In general, physical activity can be classified into one of four domains (i.e., leisure, occupation, transportation, and activities of daily living). Thus, physical activity questionnaires may differ in the types of activities they try to capture. Since it is imperative to capture accurate information on the types of activities that elicit the greatest energy expenditure in the targeted population, you may need to find a physical activity questionnaire that measures more than one domain (i.e., leisure and occupational physical activity). It is important to note that while questionnaires are accurate measuring moderate- to vigorous- intensity, they are less accurate with light intensity activities which make assessing activities of daily living (ADL) difficult to query via questionnaire. Many researchers find it most useful to measure physical activity during leisure because there tends to be little between person variation in occupation, transportation, and ADL related activities. Keep in mind that assumption of homogeneity of activity outside of leisure (occupation, transportation, and ADL) may not be valid in all populations.
Questionnaires also vary in the time frame of interest ranging from past day to participation in physical activity across the lifespan. Short term questionnaires which ask about activity performed in the past week or day provide a good estimate of an individual's current activity level; however, they may also be subject to issues of seasonality and changes in health status. It is important to note that physical activity questionnaires that utilize a shorter recall time frame may also be repeated a number of times throughout the year to provide an estimate of physical activity done over a longer period of time (i.e., four measures spaced three months apart would provide an estimate of physical activity done over the past year). Physical activity questionnaires may also ask questions about participation in activity in the past year or lifetime to provide a more general estimate of one's physical activity level. The estimates generated from these physical activity questionnaires may relate better with chronic conditions (i.e., obesity, cardiovascular disease, type 2 diabetes mellitus) which may take many years to develop.
Questionnaires may be either self- or interviewer-administered. Interview-administered questionnaires such as the MAQ require an interviewer to go through the questionnaires with the participant. It is important to train interviewers on the proper method of administering interviewer-administered questionnaires to improve the precision of the physical activity estimate. Self-administered questionnaires are completed by the participant and can either be done in-person (i.e., Women's Health Initiative Physical Activity Questionnaire) or administered via the mail (i.e., Nurses' Health Study Physical Activity Questionnaire). If using a self-administered questionnaire it is important for the study staff to review the PAQ thoroughly to make sure all items are completed properly.
The population of interest may also be an important question when deciding which questionnaire to use. Questionnaires may be designed for specific ages, gender, ethnicities, and disease. There are specific questionnaires designed for elderly populations, such as the Yale Physical Activity Survey, which ask questions about the physical activities that are most commonly performed by older adults (e.g., walking, gardening). There are also physical activity questionnaires that are designed to take differences in race/ethnicity or country into consideration, such as the International Physical Activity Questionnaire, which have translated into native languages. It is important to take these population characteristics into account in order to select the most appropriate assessment tool that has been shown to be valid and reliable in that particular population. A questionnaire that was developed for use in one population or setting (i.e., surveillance vs. intervention) may not be appropriate to use in another.