We screened 53
491 references and assessed the full text of 441 documents (fig 1). Forty eight studies met our inclusion criteria: 19 randomised controlled trials and 29 non-randomised controlled studies.w1-w60
Twenty seven studies were concerned with walking in general (tables 1, 3, and 4); 21 studies were concerned solely with walking as a mode of transport (tables 2 and 5) (see also http://sparcoll.org.uk/images/bmjsupp.pdf
Table 3 Effects of individual, house, or group based interventions on walking in general
Table 4 Effects of community level approaches on walking in general
Table 5 Effects of interventions on walking as a mode of transport
Effects of interventions on walking in general
Brief advice to individuals—Six studies w1-w6 (five randomised controlled trials) reported the effects of brief advice given face to face either in the workplacew1 or by cliniciansw2w3w6 or an exercise specialistw4w5 in primary care. A significant net increase in self reported walking was found in both studies with follow-up periods of up to six weeks,w1w2 but in only two of the four studies with longer follow-up.w3-w6
Remote support to individuals—Three randomised controlled trials evaluated interventions delivered by telephone or internet; all found a significant net increase in self reported walking.w7-w9
Group based approaches—Six studies (three randomised controlled trials) evaluated interventions involving various approaches (such as lay mentored meetings, led walks, or educational sessions) delivered in groups.w10-w16 The randomised studiesw10-w13 were more likely to find a significant net increase in self reported walking than the less robust, non-randomised studies.w14-w16
Pedometers—In seven studies (six randomised controlled trials) pedometers, coupled with various supporting measures, formed a key part of the intervention (or one intervention arm of a more complex trial).w17-w24 Three studies, all with follow-up periods of up to three months, found a significant net increase in self reported walking or in step countsw17-w20; the three studies with longer follow-up all found that a significant net increase in step counts after 4-16 weeks was not sustained at 24 weeksw22w23 or 12 months.w24
Community level approaches—Five non-randomised studies of interventions applied to whole geographical communities measured effects in whole populations rather than in those participating directly in an intervention.w25-w30 All involved a combination of approaches such as mass media campaigns augmented by community events and other local supportive measures,w27w28w30 modest environmental improvements,w25w29 formation of walking groups,w25w26w29 and written materials or brief advice for individuals.w25w26 Three studies found a significant net increase in self reported walking, but one was reported only brieflyw30 and another had significant methodological limitationsw29; the most robust evidence of effectiveness was for an intervention with a substantial mass media component.w27w28
Effects of interventions on walking as a mode of transport
Targeted or individualised promotion of active travel—One randomised controlled trial of an intervention to promote active commuting to work found a significant net increase in self reported walking.w31 Thirteen non-randomised studies of individualised marketing of “environmentally friendly modes” of transport to householdsw32-w50 consistently reported a net increase in the proportion of trips made on foot (usually measured in the local population as a whole) and an increase in time spent walking in those studies that reported this outcome.w33-w40w43-w48 The methods of these non-randomised studies, however, were often not clearly described, and only one reported the statistical significance of the observed increase in walking.w37-w40
School travel initiatives—Three studies evaluated interventions aimed at changing the mode of children's travel to school.w51-w53 Only one—a small non-randomised trial of an active commuting pack—found a significant net increase in self reported walking on the school journey.w51
Miscellaneous transport interventions—We found four other non-randomised studies.w54-w60 A directive that employers should subsidise employees who chose not to commute by car was associated with a significant increase in the proportion walking to work,w54w55 and a three year multifaceted initiative to promote cycling in a city was associated with a net increase in walking after adjustment for trends in control areas and other confounders.w56 Two less robust studies of a sustainable transport campaignw57 and a car sharing clubw58-w60 found no significant effect on walking.
Characteristics of interventions found to be effective
The most convincing evidence of effectiveness was for interventions delivered at the level of the individual or household or through group based approaches. Although no single method of promoting walking emerged as the most effective, and we were not able to reach any conclusions about the relative merits of different types of provider (such as doctor, nurse, exercise specialist) on the effectiveness of interventions, we were able to identify two general characteristics of those interventions found to be effective: targeting and tailoring.
Targeting—Most interventions associated with an increase in walking as a mode of transport were offered only to those individuals or households identified through prior screening as already motivated to change their behaviour.w31-w50 Interventions to promote walking in general were often aimed at target groups such as sedentary people or patients with particular conditions. Many of the interventions found to be effective were targeted at sedentary peoplew1 w2 w4 w7 w9 w11 w17 w18; the potential value of such targeting was also shown indirectly by other studies in which significant net increases in walking were observed only in the most sedentary subgroup within the study population.w8 w27 w28 w30 The value of targeting specific clinical populations was less clear. A group based lay mentoring intervention for patients with heart disease was effective,w10 but studies of other approaches (brief advice or pedometers) targeted at patients with diabetes or osteoarthritis did not find them to be effective at final follow-up.w5 w22 w23
Tailoring—Effective interventions typically involved content tailored to participants' requirements or circumstances. Such tailoring ranged from the provision of individualised counsellingw1 w2 w8 or written materialsw17 w18 (for example, tailored to the participant's position in the transtheoretical model of behaviour change), through inviting households to choose from a menu of information resources and incentives promoting environmentally friendly modes of transport,w32-w50 to the mapping of individual children's journeys to school.w51
Magnitude and social distribution of effects on walking
Magnitude of effect—Evidence from the most promising studies suggests that, among targeted participants, successful interventions could increase walking in general by up to 30-60 minutes a week on average; more robust studies were most likely to report significant net increases in walking than less robust studies (fig 2). In the transport sector, successful interventions could increase walking as a mode of transport in the general population by rather less, up to about 15-30 minutes a week on average; this estimate depends on a group of studies that are larger but less robust than the studies of walking in general (fig 3).
Effects on overall physical activity and health
Twenty studies reported effects on overall measures of physical activity (see http://sparcoll.org.uk/images/bmjsupp.pdf
). Of these, seven reported some evidence of a net increase in overall physical activity at final follow-up, but in each of these studies different measures of physical activity gave conflicting results.w1w2w4w10w14w16w18
Three of the studies that found a significant net increase in walking also reported effects on cardiorespiratory fitness or functional capacity in terms of maximal oxygen uptake (VO2max) or one mile (1.6 km) walking time in sedentary women or adolescent girlsw9w17 or exercise tolerance in adults with ischaemic heart disease.w10 None found a significant difference between intervention and control groups.
Two of the studies that found a significant net increase in walking also reported effects on other risk factors (anthropometry, resting heart rate, blood pressure, lipid profile, or fasting blood glucose) in specific clinical populations (adults with ischaemic heart diseasew10 or type 2 diabetesw23). Neither found any significant differences between intervention and control groups.
Six of the studies that found a significant net increase in walking also reported effects on self reported health, wellbeing, or quality of life measured with either a generic instrument such as the SF-36 or a more specific symptom or mood score. Three found a significant overall difference between intervention and control groupsw3 w9 w11; two found significant differences, but only on subscales of the SF-36w10 w31; one found no significant difference.w12 w13
Adverse effects and economic evaluation
Few studies attempted to ascertain adverse effects; none reported adverse effects such as an increase in injuries clearly attributable to an intervention to promote walking. Only six studies included even a rudimentary economic evaluation.w27 w28 w32 w37-w40 w44 w49 w54 w55 We were therefore unable to synthesise any meaningful data with which to compare these aspects of alternative approaches to promoting walking.