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Monday, 21 October 2013

Does housework count towards exercise targets?

Does housework count towards exercise targets? "Housework is not exercise," reports the Mirror today. It goes on to say that cleaning is "not intense enough" and that those who disagreed "were often fat".

This provocative story is based on an analysis of survey data from more than 4,000 adults in Northern Ireland. It found that people reported that domestic activities such as housework, gardening or DIY made up a large part of their moderate to vigorous physical activity.

However, those who reported more domestic activity tended to have higher body mass indexes (BMIs) than those who reported less domestic activity.

The researchers make the case that people may have fallen into the trap of thinking that all domestic chores automatically count towards activity targets.

This study does have a number of limitations. For example, it assessed both physical activity and BMI at the same time, so it is not possible to say from these results which one influenced the other.

Activity needs to make you out of breath or sweaty to count as moderate to vigorous. If it doesn’t, it doesn’t count towards your physical activity target of at least 150 minutes a week.

This study should act as a reminder that the intensity of activity is important as well as the amount and type of activity.

Where did the story come from?

The study was carried out by researchers from the University of Ulster and other research centres in the UK. No specific funding was reported for the study itself, but the original survey was funded by Sport Northern Ireland.

The study was published in the peer-reviewed journal BMC Public Health. The journal is open access so the study is free to read online or download.

In general, the coverage of this study was not very good, with many newspapers and website reports misinterpreting the results.

For example, suggestions that “housework and DIY are not strenuous enough to count towards people's activity targets” are unsupported. It is not possible to say this with certainty based on this study.

The Mirror story is not accurate, and the Daily Mail report contains a similar suggestion that those who “counted housework as exercise were fatter”. People were asked what activities they did and whether the activities usually made them out of breath or sweaty – not whether they considered housework to be exercise. The Mail does, however, at least report on some of the alternative explanations for the findings.

The general tone of the reporting that housework does not ‘count’ as exercise is not what the researchers conclude. The researchers do suggest that, by itself, domestic activity may not be enough to meet activity guidelines, and that a wide range of activities should be encouraged. They also make the point that it is important to consider whether the intensity of the activity is enough for it to count towards the activity recommendations.

What kind of research was this?

This was a cross-sectional study that looked at how much domestic physical activity contributed to total weekly physical activity among people in Northern Ireland, and how this related to their body mass index (BMI).

Current UK recommendations are that adults should do at least 150 minutes of moderate intensity physical activity a week. However, studies have suggested that more than half of the population does not meet this target.

To encourage people who are sedentary to do at least some activity, more emphasis has been placed recently on a 'lifestyle' approach, of building physical activity into the daily routine. For example, normal domestic activities such as DIY, gardening or housework have been promoted.

However, the researchers say that there is a risk that people assume that these activities are always of moderate intensity, but this may not be the case.

As a cross-sectional study the main limitation of this study is that it cannot show that one factor causes the other. Therefore, it can't tell us how someone’s physical activity has affected their BMI, or vice versa.

What did the research involve?

The researchers analysed survey data on physical activity, height and weight collected from 4,563 adults in Northern Ireland. They looked at how domestic activities contributed to a person’s total physical activity and whether this was related to their BMI.

The data the researchers used was collected in face-to-face interviews using computer-assisted personal interviewing, as part of the Northern Ireland Sport and Physical Activity Survey. The sample was selected to be representative of the Northern Ireland population. Just over half of those invited to take part (54.6%) did so.

The interview asked about participation in sport and physical activity, perceived health and happiness, fruit and vegetable intake, alcohol consumption and smoking habits, as well as socioeconomic information.

Participants were asked about any physical activity in the home (domestic physical activity) that raised their breathing rate over the week. Domestic physical activity was classified into four categories:

housework
DIY
gardening
other domestic activity (this was not explained further in the study)

Total time spent in domestic physical activity in periods of 10 minutes or longer was recorded. For each activity, participants were asked to report whether the activity was “usually enough to make them out of breath or sweat”. If they answered 'yes' this was considered moderate to vigorous intensity physical activity, and if they answered 'no' this was considered low intensity.

The researchers looked at the relationship between different types of physical activity (at work, at home/domestic, sporting, cycling and walking activities) and a BMI ratio. They took into account age, gender, smoking and socioeconomic status in their analyses.

What were the basic results?

Almost half of the people surveyed (42.7%) reported meeting or exceeding current UK recommended levels of physical activity. Domestic activities were reported to account for more than a third of respondents’ moderate to vigorous physical activity. Women and older adults reported higher levels of domestic moderate to vigorous physical activity than men and younger adults.

Excluding this activity would result in a reduction in the number of people meeting UK recommended levels of physical activity. For example, among women, excluding domestic activities meant that only about a fifth (20.4%) met recommendations.

People who reported more moderate to vigorous domestic physical activity tended to have higher BMIs than those who reported less moderate to vigorous domestic physical activity. The results of the analyses of the other types of physical activity and BMI were not reported.

How did the researchers interpret the results?

The researchers concluded that domestic activities account for a considerable proportion of self-reported daily moderate to vigorous physical activity, particularly among women and older adults.

However, those reporting more domestic physical activity tend to be less lean, suggesting that this activity may not be enough to provide all of the benefits normally associated with meeting the physical activity guidelines.

Conclusion

This cross-sectional study has found that people in Northern Ireland who reported doing more physical activity in a domestic setting (such as housework, gardening or DIY), tended to have higher BMIs.

However, the study does have a number of limitations that could have influenced the results:

The study assessed physical activity and BMI at the same time. This means we can’t be sure which factor might be influencing the other. For example, individuals with high BMIs may find domestic activities harder work than those with lower BMIs, and this could result in them classing more of these activities as moderate to vigorous.
The researchers did not assess people’s calorie intake. It is possible that those who did more domestic activities also consumed more calories. The study was based on people reporting their own physical activity, and these reports may not be accurate. They may not be good at estimating exactly how long they do activities for, or how strenuous these activities are. They may also be reluctant to report their true levels of activity. Studies that use monitors attached to the body to detect physical activity would give a more reliable measure.
It is not clear whether the analyses looking at the link between domestic activity and BMI took into account the total amount of reported moderate to vigorous activities. People who did more domestic activities may have done less moderate to vigorous physical activity as a whole, and this could account for the link with higher BMI.
About half of those invited to take part in the survey did not do so. Therefore, the sample may not be representative of the entire Northern Irish population. It may also not be representative of people in other countries.

These limitations mean that we cannot conclude from this research that doing domestic activities definitely doesn’t count as moderate to vigorous physical activity. As the authors themselves point out, any activity is better than none, particularly if it is done instead of being sedentary.

However, we do need to be aware that modern housework, DIY and gardening are likely to be much less energy-intensive than they used to be. The study should act as a reminder that an activity needs to make us out of breath or sweaty to count towards our physical activity target.

Recommended activities that count as moderate to vigorous exercise include jogging, cycling, swimming and fast walking.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.