Validation of an Internet-based long version of the International Physical Activity Questionnaire in Danish adults using combined accelerometry and heart rate monitoring.

BACKGROUND: The International Physical Activity Questionnaire (IPAQ) is commonly used in surveys, but reliability and validity has not been established in the Danish population. METHODS: Among participants in the Danish Health Examination survey 2007-2008, 142 healthy participants (45% men) wore a unit that combined accelerometry and heart rate monitoring (Acc+HR) for 7 consecutive days and then completed the IPAQ. Background data were obtained from the survey. Physical activity energy expenditure (PAEE) and time in moderate, vigorous, and sedentary intensity levels were derived from the IPAQ and compared with estimates from Acc+HR using Spearman's correlation coefficients and Bland-Altman plots. Repeatability of the IPAQ was also assessed. RESULTS: PAEE from the 2 methods was significantly positively correlated (0.29 and 0.49; P = 0.02 and P < 0.001; for women and men, respectively). Men significantly overestimated PAEE by IPAQ (56.2 vs 45.3 kJ/kg/day, IPAQ: Acc+HR, P < .01), while the difference was nonsignificant for women (40.8 vs 44.4 kJ/kg/day). Bland-Altman plots showed that the IPAQ overestimated PAEE, moderate, and vigorous activity without systematic error. Reliability of the IPAQ was moderate to high for all domains and intensities (total PAEE intraclass correlation coefficient = 0.58). CONCLUSIONS: This Danish Internet-based version of the long IPAQ had modest validity and reliability when assessing PAEE at population level.

Validity of the international physical activity questionnaire in the arctic.

PURPOSE: Information about physical activity (PA) in Greenland is limited, partly because of a lack of validated instruments in countries with non-Western living conditions. We modified the long form of the International Physical Activity Questionnaire (IPAQ-L) to arctic living conditions. The aim of the study was to compare IPAQ-L estimates with combined accelerometry and heart rate monitoring (ACC + HR) in a population-based study of adult Inuit in Greenland. METHODS: Cross-sectional data were collected by face-to-face interview and ACC + HR monitoring among Inuit (18 yr and above) in Greenland during 2005-2010 (n = 1508). PA energy expenditure (PAEE) and time spent sedentary and on PA at moderate and vigorous intensity were derived from IPAQ-L and ACC + HR. Estimates were compared using Bland-Altman agreement analysis and Spearman correlations stratified by sex, place of residence (capital, towns, and villages), and age groups. RESULTS: Questionnaire-based PAEE was moderately correlated with objectively measured PAEE (r = 0.20-0.35, P < 0.01). Self-reported time spent at moderate- and vigorous-intensity PA and time spent sedentary were weakly correlated with the objective measure (r = 0.11-0.31). Agreement analyses showed relatively small median differences for all measures of PA; however, time spent at moderate-intensity PA was substantially overreported by IPAQ-L when including walking (>1.5 h·d, P < 0.001) but not when excluding walking. CONCLUSIONS: The IPAQ-L adapted to arctic living conditions in Greenland had a moderate level of agreement with combined accelerometry and heart rate monitoring for total PAEE at population level, but it was less valid to measure different intensities of PA and sedentary activity. Validity did not differ markedly between rural and urban communities.

Effect of a Web-based intervention to promote physical activity and improve health among physically inactive adults: a population-based randomized controlled trial.

BACKGROUND: Many people in Western countries do not follow public health physical activity (PA) recommendations. Web-based interventions provide cost- and time-efficient means of delivering individually targeted lifestyle modification at a population level. OBJECTIVE: To examine whether access to a website with individually tailored feedback and suggestions on how to increase PA led to improved PA, anthropometrics, and health measurements. METHODS: Physically inactive adults (n = 12,287) participating in a nationwide eHealth survey and health examination in Denmark were randomly assigned to either an intervention (website) (n = 6055) or a no-intervention control group (n = 6232) in 2008. The intervention website was founded on the theories of stages of change and of planned behavior and, apart from a forum page where a physiotherapist answered questions about PA and training, was fully automated. After 3 and again after 6 months we emailed participants invitations to answer a Web-based follow-up questionnaire, which included the long version of the International Physical Activity Questionnaire. A subgroup of participants (n = 1190) were invited to a follow-up health examination at 3 months. RESULTS: Less than 22.0% (694/3156) of the participants logged on to the website once and only 7.0% (222/3159) logged on frequently. We found no difference in PA level between the website and control groups at 3- and 6-month follow-ups. By dividing participants into three groups according to use of the intervention website, we found a significant difference in total and leisure-time PA in the website group. The follow-up health examination showed no significant reductions in body mass index, waist circumference, body fat percentage, and blood pressure, or improvements in arm strength and aerobic fitness in the website group. CONCLUSIONS: Based on our findings, we suggest that active users of a Web-based PA intervention can improve their level of PA. However, for unmotivated users, single-tailored feedback may be too brief. Future research should focus on developing more sophisticated interventions with the potential to reach both motivated and unmotivated sedentary individuals. TRIAL REGISTRATION: Clinicaltrials.gov NCT01295203; http://clinicaltrials.gov/ct2/show/NCT01295203 (Archived by WebCite at http://www.webcitation.org/6B7HDMqiQ).

The effect of reminders in a web-based intervention study.

Knowledge on effective strategies to encourage participation in epidemiological web-based research is scant. We studied the effects of reminders on overall participation. 3,876 employees were e-mailed a baseline web-based lifestyle questionnaire. Nine months later, a follow-up questionnaire was sent. To encourage study participation, 4-5 and 11 e-mail reminders were sent at baseline and follow-up, respectively. Additional reminders (media articles, flyers, SMS etc) were also administered. Reminders (e-mails + additional) were given in low (≤ 6 reminders), medium (7-9 reminders) or high amounts (>9 reminders). Participation was examined with respect to participant characteristics (i.e. age, sex, Body Mass Index, occupation), type/number of reminders, and time of participation. Most participants were males, 35-49 years, and field workers (non-office based). About 29 % responded before any e-mail reminder, following 26 and 45 % after 1 respective ≥ 2 e-mail reminders. Participant characteristics were not related to when the participants responded. The 4-5 e-mail reminders increased total response rate by 15 %, the eleven by 21 % (greatest increases in September). Those receiving medium amounts of reminders (reference) had the highest response rate (75 %), likewise office workers (54 %) compared to field workers (33 %). High amounts of reminders were particularly effective on office workers. The participants' characteristics were not related to when they responded in this web-based study. Frequent reminders were effective on response rates, especially for those with high Internet availability. The highest increases in response rates were found in September.

A population-based randomized controlled trial of the effect of combining a pedometer with an intervention toolkit on physical activity among individuals with low levels of physical activity or fitness.

OBJECTIVES: To examine if receiving a pedometer along with an intervention toolkit is associated with increased physical activity, aerobic fitness and better self-rated health among individuals with low levels of physical activity or fitness. METHODS: The intervention was nested in the Danish Health Examination Survey (DANHES) and carried out in 2008. Participants were randomly assigned to either a pedometer group (n=326) or a control group (n=329). Physical activity, aerobic fitness, and self-rated health were measured at baseline and at 3-month follow-up, and differences were tested by Wilcoxons signed rank tests and Chi-squared tests. RESULTS: At follow-up, no significant differences in physical activity, aerobic fitness and self-rated health were found between the groups. However, the oldest participants in the pedometer group reported significantly more walking time compared to the controls (controls=368 min/week, pedometer group=680 min/week, P=0.05). Among participants who completed the intervention, a significant effect on total walking time was observed (median difference=225 min/week, P=0.04). CONCLUSIONS: The results suggest that receiving a pedometer and along with an intervention toolkit can increase walking time in older individuals, but not in younger individuals. Thus, this type of intervention offers great potential for promoting physical activity in older individuals. TRIAL REGISTRATION NUMBER: NCT01071811.