4363.0.55.001 - Australian Health Survey: Users' Guide, 2011-13
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 19/07/2013
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ADULT PHYSICAL ACTIVITY
Walking was defined as requiring a 10 minute minimum threshold per session, and aimed to include continuous walking, excluding activities such as walking around a shopping centre as people tend to frequently pause while shopping. Walking for transport and walking for fitness, recreation or sport were collected separately. Moderate intensity physical activity/exercise was defined as activities that caused a moderate increase in the heart rate or breathing of the respondent. Vigorous intensity physical activity/exercise was defined as activities that caused a large increase in the respondent's heart rate or breathing. Moderate and vigorous physical activity/exercise excluded previously identified walking as well as household chores, gardening or yard work. Population Information was collected for selected persons:
Methodology Respondents were asked a series of questions about the physical activity/exercise they undertook in the last week. Physical activity (adults) was collected in both the NHS and the NNPAS surveys with similar questions. Information on adult exercise level data was first published in First Results using NHS data and referred to a sample of approximately 16,000 people aged 15 years and over and 15,000 people aged 18 years and over. Exercise level data was also used in cross-tabulations for the Health Service Usage and Health Related Actions datacubes. More detailed information on adult physical activity data was published in Physical Activity, using NNPAS data and referred to the sample of approximately 9,000 people aged 18 years and over. Data from the combined samples in the Australian Health Survey is also available and comprises of people aged 18 years and over for a sample of approximately 25,000. For comparison of adult physical activity with NHS only items, the NHS file should be used and similarly for comparison with NNPAS only items, the NNPAS file should be used. However, for the most accurate information for physical activity alone or comparison with other items collected in the core, the core file should be used. For more information on the structure of the AHS, see the Structure of the Australian Health Survey page of this Users' Guide. Whether met guidelines Data on physical activity was collected in order to report against the National Physical Activity Guidelines for Australian adults (18 years and over) which recommend at least 30 minutes of moderate-intensity physical activity on most, preferably all, days. This has been represented by the following three measures:
The NNPAS collected data that could produce results for the first two measures. The NHS collected data for all three. Data is collected for this topic for 15 to 17 year olds in NHS but data items for ‘whether met guidelines’ are not applicable. To measure against the Guidelines, the data collected was for leisure-time physical activity, in line with Active Australia. NHS collected these questions using the concept of ‘exercise’. NNPAS collected these questions using the concept of ‘physical activity’. The questions used were generally the same in NHS and NNPAS and included:
Moderate and vigorous activity excluded household chores, walking, gardening and yard work. For each of these domains of physical activity, respondents were asked:
From this information the following items were derived for persons 18 years and over:
2 The ‘Level of (exercise/physical activity)’ items were created with the aim of producing a descriptor of relative overall physical activity level, and to indicate the quality of the activities undertaken in terms of maintaining heart, lung and muscle fitness. Intensity, or Metabolic Equivalent of Task (MET), is a measure of the energy expenditure required to carry out the exercise, expressed as a multiple of the resting metabolic rate (RMR). This item has historically been used in NHS output. As a result, this item was produced as two versions, to allow time-series to be produced which excludes walking for transport in the calculation. Note that for these two items, NHS also includes data for 15 to 17 year olds. 3 As the NHS does not collect details of the types of activities undertaken, an intensity value was estimated for each of the three domains of exercise identified in the survey, as shown in the above formula. For comparability purposes, NNPAS has also utilised the allocated intensity value. While NHS and NNPAS data is generally comparable, care should be used when interpreting the data. Differences in collection including terminology, questions used and ordering are outlined in the Interpretation section. Days exercised for at least 30 minutes In the NHS, following on from the walking, moderate and vigorous physical activity questions, respondents were asked on how many days they exercised, and, of those days, how many they did exercise for at least 30 minutes. These questions were asked in order to measure against the 5 days and 30 minutes recommendation that is used in physical activity campaigns. Typical work day Employed respondents were then asked which of the following best describes what they do on a typical work day:
Vigorous gardening As part of the collection of walking, moderate and vigorous physical activity, the NNPAS also collected data on duration and number of sessions of vigorous gardening. This was keeping consistent with the Active Australia questions, where it is utilised to ensure that this data is not included in the vigorous data. The New Zealand Physical Activity Questionnaires report states that the intensity of gardening and yard work is often over-reported, and so it has not been included in any of the derived physical activity items. Despite the over-reporting issue, the recent article by Peeters et al. Contribution of house and garden work to the association between physical activity and well-being in young, mid-aged and older women suggests a correlation exists between mental and physical well-being and gardening, in particular for older women. As it may contribute to further research into physical activity patterns and correlations, the data are available for users to do their own analysis. Type of activity/whether organised/MET After the NNPAS set of physical activity questions, respondents were asked to specify the types (up to 10) of moderate/vigorous activities they had participated in, in the last week, and indicate for each activity whether some, all or none of it was organised by a club, association or other such organisation. The activities have had a classification applied, based on that used in the ABS Participation in Sport and Physical Recreation Survey. This data is presented on the Adult Physical activity level, so that each activity can be identified as having been organised/not organised or both. In processing this type of activity data, MET scores were applied to each physical activity reported using the 2011 Compendium of Physical Activities. In the compendium some activities have multiple MET scores (depending on intensity, or specific type, for example). Where this was the case, the lowest score on or above the moderate activity threshold was assigned, even if the respondent identified that they had only undertaken vigorous activity in the preceding questions. The MET scores associated with each reported activity have been provided as a data item for reference purposes. For the purposes of calculating against physical activity recommendations in this survey, the MET scores have not been used. This was for consistency with the NHS and other surveys that use the Active Australia questions, and also as some activities are identified as having the MET of less than 3 but the respondent had identified that for them it was considered moderate or vigorous intensity. As the MET scores have been generically applied to the activities, use of these should be with caution. The MET scores assigned are outlined in Appendix 6 with the Adult physical activity classification. Strength and toning Following the moderate/vigorous questions, NNPAS respondents were asked to report on the duration and number of sessions of strength and toning activities they had done in the last week. Muscle strength and toning activity can help maintain bone strength and reduce the risk of osteopenia or osteoporosis. These activities were defined as being designed to increase muscle strength or tone, such as lifting weights, pull-ups, push-ups, or sit-ups. These sessions were meant to be undertaken with the specific intention of strength and toning, and not include incidental activity, such as carrying or lifting wood for a wood fire or heavy grocery bags. Responses to these questions could include activities for which they had already reported, such as part of training sessions that were considered to meet moderate/vigorous intensity. Active Transport NNPAS respondents were then asked to identify the ways they got from place to place in the last week. Categories for this question were worded with the aim of being able to produce active versus inactive transport data. Active transport categories are:
Data items The data items and related output categories for this topic are available in Excel spreadsheet format from the Downloads page of this product. Interpretation Points to be considered when interpreting data relating to physical activity (walking, moderate, vigorous activity):
In addition to the above points, the following collection differences between the NHS and NNPAS should be considered. Terminology NNPAS uses the term 'physical activity' where NHS uses 'exercise’. The WHO definition of physical activity states:
So in essence NNPAS collects a broader concept of activity than NHS. Significance testing showed that levels of reporting were not greatly affected by the terminology difference. Question ordering The order of the NNPAS walking questions and moderate and vigorous questions was reversed from those asked in NHS. Ordering of the walking questions has produced some statistically significant differences between the data produced by the two surveys. NHS, which asked about walking for fitness first, had more respondents reporting this activity than for transport, whereas for NNPAS, where the questions were reversed so walking for transport was asked first, more respondents reported walking for transport. Data items produced using total walking times (e.g. Level of physical activity in last week including walking for transport) are not affected by the different collection methods for walking. Where only walking for fitness (e.g. Level of physical activity undertaken for fitness, recreation or sport in last week (time series)) is used in an item, there may be some impact from the ordering effect when comparing between surveys or using NNPAS data (as walking for transport was asked first and therefore lowered the number of responses for walking for fitness) and should be used with caution. For moderate and vigorous activity, NHS asks about moderate activity first and NNPAS asks about vigorous activity first. In both surveys, there is a higher number of sessions and duration reported in response to questions about the first intensity threshold asked. As factors of 7.5 and 5 are applied to vigorous and moderate activity times respectively for the ‘Level of physical activity/exercise’ items, the ordering effect of these two questions is amplified for these items if looked at by individual survey. Caution should be used if comparing the data from the two survey datasets. Combining the datasets (for the Core file) reduces the impact of this ordering effect. The ordering effect is not as apparent for other data items which do not have multiplying factors or have lower factors. Vigorous gardening and other issues The NNPAS calculation of physical activity excludes vigorous gardening data, though there are separate questions to collect information on vigorous gardening activity. NHS did not collect this separately, and although the question collecting exercise excluded gardening, it is possible that some gardening was included in NHS responses. It is expected that the separation of the question in NNPAS has increased the likelihood of reporting and as a result the extent to which NHS respondents may have included it in their responses is not comparable to the levels identified by the NNPAS questions. This difference in collection should be considered if making comparisons of total activity between the two surveys. As mentioned in the methodology section, responses for type of moderate/vigorous activity in NNPAS have generally been left as reported even if the MET intensity did not meet a moderate intensity level. However, where walking was identified, where possible this data was moved to the walking for fitness question. Comparability with 2007-08 NHS The majority of the 2011-12 NHS data on exercise and sedentary behaviours were collected with the same methodology and questions used in the 2007-08 survey, and therefore most results are considered directly comparable. The following changes, however, should be noted:
Comparability with Active Australia surveys This topic uses the Active Australia questionnaire, which allows comparisons to be made with other surveys that have used the same questionnaire. It captures the total amount of physical activity for the week prior to interview by number of sessions and duration of each activity domain. Some modifications have been made to the original questions for use in ABS health surveys:
As a result of these modifications, as well as different collection methodologies that are used by other surveys (such as telephone interviews), some care should be used when comparing AHS survey data with other surveys that use the Active Australia questions.
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