Reliability and validity of the Past Year Total Physical Activity Questionnaire

Accelerometer-measured daily physical activity among octogenerians: results and associations to other indices of physical performance and bone density

Information on objectively assessed physical activity in elderly people is scarce. The aim of this study was to investigate accelerometer measures in elderly women, and its relation to other indices of physical activity and bone density. A subset of 57 women, all 80 years old, (range 80.0-80.7) of the Malmö OPRA study was equipped with an MTI accelerometer for a period of 5-7 days. A 7-day activity log was used. At baseline a self-assessment questionnaire was used and isometric muscle strength (knee), gait speed, balance and bone density measurements [dual-energy X-ray absorptiometry (total body, hip, and spine), and quantitative ultrasound of the calcaneus] were measured. About 14% (8 out of 57) had a moderate to vigorous physical activity (MVPA) (>1,952 counts per min [CPM]) exceeding 30 min/day. The median CPM was 18. When compared to questionnaire data, the correlation between MVPA and physical activity was 0.50 (P < 0.001). The corresponding result for CPM was 0.48, P < 0.001. When compared to the activity log, the correlation between MVPA and physical activity away from home was 0.49 (P < 0.001). The corresponding result for CPM was 0.55, P < 0.001. The correlation between MVPA and gait speed was 0.41 (P = 0.002). The corresponding result for CPM was 0.40, P = 0.002. There were no correlations to the measurements of muscle strength, balance or bone density (all P > or = 0.07). Accelerometers can be used for measuring of physical activity also of the elderly. Questions on daily physical activity correlated modestly with accelerometer results in elderly women. Accelerometer results were not correlated to measures of balance, muscle strength and bone density.

Epidemiological studies of physical activity and diabetes risk, and implications for diabetes preventionThis paper was originally part of the Symposium “Exercise, insulin sensitivity and diabetes—what’s new?”, which appeared in the June issue of Appl. Physiol. Nutr. Metab

The evidence linking physical inactivity to the future risk of type 2 diabetes is strong, and modification of behaviour is a critical and effective element of strategies aimed at the prevention of this increasingly prevalent disorder. Two key unresolved epidemiologic issues relate to the type of activity that is likely to be maximally effective in preventing diabetes and the amount of activity that is required. Resolution of both these issues is likely to require a change in the way activity is measured, with a move away from self-report instruments, toward objective assessment of activity and the pattern and overall level of energy expenditure. It is also unclear whether the impact of physical activity on metabolic risk is homogenous across the population. Subgroups that might respond differently could be defined on the basis of characteristics such as age, degree of obesity, family history, ethnicity, and genetic risk, but the literature on effect modification is limited by study design issues. The identification of such subgroups could aid in the targeting of preventive interventions. An appropriate balance between individually tailored approaches aimed at those at high risk and interventions aimed at trying to shift physical activity levels in entire populations remains to be determined.

Modeling time-location patterns of inner-city high school students in New York and Los Angeles using a longitudinal approach with generalized estimating equations

The TEACH Project obtained subjects' time-location information as part of its assessment of personal exposures to air toxics for high school students in two major urban areas. This report uses a longitudinal modeling approach to characterize the association between demographic and temporal predictors and the subjects' time-location behavior for three microenvironments--indoor-home, indoor-school, and outdoors. Such a longitudinal approach has not, to the knowledge of the authors, been previously applied to time-location data. Subjects were 14- to 19-year-old, self reported non-smokers, and were recruited from high schools in New York, NY (31 subjects: nine male, 22 female) and Los Angeles, CA (31 subjects: eight male, 23 female). Subjects reported their time-location in structured 24-h diaries with 15-min intervals for three consecutive weekdays in each of winter and summer-fall seasons in New York and Los Angeles during 1999-2000. The data set contained 15,009 observations. A longitudinal logistic regression model was run for each microenvironment where the binary outcome indicated the subject's presence in a microenvironment during a 15-min period. The generalized estimating equation (GEE) technique with alternating logistic regressions was used to account for the correlation of observations within each subject. The multivariate models revealed complex time-location patterns, with subjects predominantly in the indoor-home microenvironment, but also with a clear influence of the school schedule. The models also found that a subject's presence in a particular microenvironment may be significantly positively correlated for as long as 45 min before the current observation. Demographic variables were also predictive of time-location behavior: for the indoor-home microenvironment, having an after school job (OR=0.67 [95% confidence interval: 0.54:0.85]); for indoor-school, living in New York (0.42 [0.29:0.59]); and for outdoor, being 16-year-old (0.80 [0.67:0.96]), 17-year-old (0.71 [0.54:0.92]), and having an after school job (1.29 [1.07:1.56]).

Reproducibility of the past year and historical self-administered total physical activity questionnaire among older women

Few studies have evaluated the reliability of a self-administered current and historical physical activity questionnaire (PAQ) among middle-aged and elderly women. We evaluated the reliability of a self-administered PAQ designed to assess total (24 h) current and historical physical activity at age 15, 30, and 50 years, which was completed by a subgroup of 303 women aged 56-75 years from the Swedish Mammography Cohort (SMC). Total physical activity covered occupational and household activity as well as walking/bicycling, exercise, and inactivity (sitting watching TV/reading). Reliabilities (1-year test-retest) of continuous activity measures in metabolic equivalents were evaluated using an intraclass correlation coefficient (ICC); classification consistency was evaluated using sensitivity and specificity statistics. The ICC for total current physical activity was 0.69; for specific types of activities the ICC ranged from 0.49 to 0.59; for historical physical activity, the reliabilities for total activity ranged from 0.75 for age 50 to 0.81 for age 30 years, being substantial for occupational activities (ICC = 0.73-0.75), and fair to moderate for inactivity (ICC = 0.31-0.60). These data indicate that the PAQ used in the SMC is a satisfactory and reproducible measure of current and historical physical activity, for total as well as for different types of activities.