Does doing housework keep you healthy? The contribution of domestic physical activity to meeting current recommendations for health

Current United Kingdom physical activity guidelines suggest that adults should undertake 150 minutes of moderate intensity physical activity per week [1]. Despite the health benefits associated with physical activity more than half of the population fail to meet the current recommended activity levels known to enhance health [2, 3]. In an effort to encourage sedentary individuals to engage in at least some physical activity, emphasis has shifted from promoting structured forms of exercise and physical activity to lifestyle activities which can form part of a normal daily routine. This shift is based on the assumption that promoting such activity will persuade more people to become active and eventually reach levels of physical activity which meet the current guidelines. Accordingly, physical activity promotional campaigns have encouraged people to look for opportunities during normal daily life to incorporate activity into their daily routines [4] (http://www.nhs.uk/Change4Life/Pages/daily-activity-tips.aspx). This lifestyle approach to physical activity includes the promotion of domestic physical activities such as do-it-yourself or home maintenance, gardening and housework. Although cross-sectional and cohort studies have shown that domestic physical activity is associated with reduced all-cause mortality the evidence for an association between this type of activity and cardiovascular disease risk has been equivocal [5, 6]. An analysis of survey data from 30 European countries has shown that domestic physical activity is only weakly associated with measures of health (self-rated health and BMI) compared to leisure time physical activity [7].

Besson and colleagues (2008) have shown that while intense domestic physical activities (>5METS) are associated with a reduction in all-cause mortality among older adults when these more intense activities are removed from the analysis the association between domestic activity and all-cause mortality disappears highlighting the importance of intensity of activity as an important mediator of the health benefits of activity. Although it is widely acknowledged that any activity is better than none, particularly when such activity replaces sedentary behaviours, there is a danger that those undertaking routine domestic ‘chores’ may assume that this activity is moderate intensity and therefore counts towards this 150 minute per week target. While some laboratory studies have shown that certain domestic physical activities such as sweeping, window cleaning, vacuuming and lawn mowing performed at a self-selected pace are moderate intensity for middle aged or older women there is large variability between individuals in the intensity at which such activities are performed [8]. If domestic physical activity is widely promoted as health enhancing and individuals believe that such activity is likely to result in improved health it may displace other activity known to be moderate intensity and more unequivocally linked to reduced disease risk. This issue may be particularly important for women – as domestic physical activity has been shown to make a larger contribution to total physical activity in females [9].

Excess body weight for height is now regarded as a significant population health issue with the proportion of individuals classified as overweight or obese rising in most developed countries [10]. Being overweight or obese is now recognised as an important risk factor for many chronic diseases [11] and has been shown to increase all-cause mortality while leanness is associated with reduced risk [12]. Cross-sectional studies have shown strong inverse associations between physical activity and body weight [13]. However, when observations are limited to domestic physical activity there is often little or no association with overweight and obesity [14].

The aims of this paper are to determine the contribution of domestic physical activity to meeting current physical activity guidelines in the Northern Ireland population, and to explore the relationship between domestic physical activity and leanness in this population.

When domestic physical activity is included 42% of the population (men 46% women 40%) meet current physical activity recommendations of ≥ 150 mins of MVPA per week. For women, if domestic physical activity was excluded from their total MVPA, only 20.4% would be deemed to meet current recommendations

When we explored the effect of various sources of physical activity (at work, at home/domestic, sporting, cycling, and walking activities) on iBMI, having controlled for the confounding effects of age, gender, socio-economic and smoking status, time spent in domestic physical activity at moderate to vigorous intensity was found to be a negative covariate (P = 0.024), [R Squared = .132 (Adjusted R Squared = .125)].

In this cross-sectional study over two thirds of participants reported taking part in at least one 10 minute bout of domestic physical activity which they rated as moderate to vigorous in intensity (usually enough to make them out of breath or sweat). This compares with the Scottish Health Survey where, 42.9% of men and 39.8% of women reported participating in 20 minutes of intense domestic physical activity [6]. The differences between the two findings are likely to be due to differences in the threshold used for measuring physical activity. The 20 minute threshold employed in the Scottish survey is likely to have resulted in a slightly lower proportion of respondents who were categorised as having reported moderate to vigorous intensity domestic physical activity. Irrespective of these differences our finding underscores the prevalence of domestic physical activity in the adult population and the degree to which such activity is perceived to be at least moderate intensity. The prevalence of moderate to vigorous domestic physical activity was not equally distributed throughout the population. Domestic physical activity accounted for 34.9 (+0.8)% of all reported MVPA for women whereas among men it only accounted for 19.8 (+0.8)% of total MVPA. This gender difference is in keeping with other self-report surveys of physical activity and probably reflects both the greater role that women traditionally play in completing household chores and/or the degree to which this activity is perceived as moderate intensity. In both genders the contribution of domestic physical activity to self-reported MVPA increases with age. For females over 21 years who reported at least 10 mins of moderate to vigorous domestic physical activity, this source accounts for more than 50% of total MVPA. Indeed if domestic physical activity was eliminated from the analysis less than 21% of the females taking part in this survey would be deemed to have met current physical activity recommendations. This finding reflects the results of analysis from Scottish and Australian surveys where eliminating domestic physical activity significantly reduced the proportion of the population who were deemed to meet current physical activity guidelines [9, 15].

In our analysis, domestic MVPA was negatively associated with leanness. One explanation for the negative association observed in this analysis is that less lean individuals may self-report domestic activities as being more intense than their leaner counterparts. Domestic activity often involves smaller muscle groups and isometric contraction which are more likely to cause fatigue and result in perceived exertion without resulting in the volume of energy expenditure likely to alter body composition. Moreover it could be speculated that fatter respondents report greater levels of moderate to vigorous intensity domestic physical activity because of their larger body mass and the difficulties associated with performing domestic tasks. The finding that domestic physical activity is inversely related to leanness is counter-intuitive. Irrespective of the intensity of domestic physical activity additional physical activity incurs additional energy expenditure and should, from a physiological perspective, be associated with greater leanness assuming energy intake is constant [16]. We speculate that those reporting the highest levels of MVPA through domestic physical activity are either over-estimating the intensity or duration of this physical activity or are over-compensating for the energy expended in such physical activity through energy intake. As suggested above, if individuals perceive that they are undertaking significant amounts of moderate or vigorous intensity physical activity through domestic activities they may be inclined to increase their energy intake which may, over time, contribute to an increase in fatness.

Recent findings from the Scottish Health Survey suggest that domestic activities do not protect against cardiovascular disease [6]. In a prospective cohort study of English older adults (>63ys) [5] reported a 19% reduction of risk of all-cause mortality attributable to domestic physical activity and an inverse association between such activity and cardiovascular mortality independent of other sources of physical activity. However when the most intense domestic physical activities (>5METS) such as mowing the lawn, digging and stair climbing were excluded the association with all-cause mortality disappeared underlining the importance of intensity of domestic physical activity for health benefit.

Given the emergence of sedentary behaviour as a risk factor for many chronic diseases the promotion of any physical activity, irrespective of intensity, is well-founded. However if public health campaigns are designed to encourage people to meet current physical activity guidelines then caution is needed in the promotion of domestic physical activity as this may be insufficient to evoke some of the favourable alterations that lead to improved health and decreased risk. Where domestic physical activity is promoted for such purposes clear messages on the intensity required should be provided so that individuals can distinguish between activities which can be counted towards the current 150 mins per week target and those which may be useful for reducing sedentary time and boosting their overall volume of physical activity but do not qualify within the current guidelines.

There are several limitations to this study including the use of self-reported physical activity, self-estimated exercise intensity and self-reported height and weight [3]. Neither energy expenditure nor dietary intake was objectively measured and therefore our explanation of the negative association between domestic physical activity and leanness remains speculative.

The negative association between domestic physical activity and leanness found in this cross-sectional study suggests that those promoting physical activity for health benefit should ensure that the importance of physical activity across a wide variety of domains is emphasised and that domestic physical activity is not seen as the main method by which sedentary individuals are encouraged to meet current physical activity guidelines.