Motivational considerations of mass media messages used to promote more physical activity and less sedentary behaviour what messages should be used?
2014-11-24T14:08:33Z (GMT) by
Physical activity guidelines have become a focal point of mass media messages promoting physical activity to the adult population. Messages regarding sedentary behaviour have also emerged. Further, Chapter 3 identified knowledge of just 18% within a large sample of highly educated and employed UK adults. Of concern is the further finding that knowledge is likely to be higher within this group than within the general population and many groups within society may therefore have even lower knowledge. As many individuals are seemingly not likely to know the current physical activity guidelines, disseminating messages to promote them appears to be a reasonable strategy. However, Chapter 1 of this thesis highlighted the lack of research investigating the efficacy of messages designed around physical activity guidelines. Chapters 4, 5 and 6 began to explore some of the possible motivational implications of messages prominent in mass media campaigns promoting physical activity guidelines. Chapter 4 describes a cross-sectional study which compared the effects of messages using the threshold of 150 minutes a week with a generic message on perceived benefits of physical activity. Messages were representative of those found in mass media campaigns. Those receiving a threshold message held significantly less positive views of the benefits of physical activity at durations below 150 minutes a week. While a threshold message may be motivationally damaging in certain contexts, they tend not to be provided in isolation. Intensity of physical activity i.e. moderate-to-vigorous (MVPA) is another key aspect of physical activity guidelines featured in mass media campaigns. Subsequently, Chapter 5 employed an online survey of highly educated adults to investigate associations between threshold and generic messages describing MVPA as either walking or using a physiological description, with motivational constructs. Interestingly, the message incorporating a threshold was motivationally advantageous when MVPA was described as walking. On the other hand, inactive adults tend to overestimate their physical activity with walking behaviour being serially overestimated. This could result in reduced motivation to engage in MVPA. The influence of regular walking speed on misperceptions was therefore investigated in Chapter 6. Further, accurate knowledge of physical activity requirements has been theorised to reduce misperceptions. Chapter 6 reports findings that regularly slow walkers are more likely to overestimate their physical activity levels while knowledge of guidelines has no effect. This leaves a complex picture of the motivational qualities of messages promoting physical activity guidelines. Finally, Chapter 7 describes a content analysis which broadens the investigation of mass media messages by scrutinising the introduction of messages promoting reductions in sedentary behaviour. Sticking closely to guidelines, combining messages on sedentary behaviour with those on physical activity, the relative omission of standing and the demonisation of sitting emerged as common themes. This thesis highlights the problem of low knowledge of physical activity guidelines within a sample of UK adults and points towards a lack of evidence-based messaging. With knowledge being low, the provision of a threshold is desirable on an informational level. The provision of walking as an exemplar appears to make the threshold more amenable, however, for inactive adults the use of this exemplar in messages may lead to overestimation of physical activity and decrease motivation. Clearly, the motivational implications of these messages are complex and require further investigation.