In 2011, Current Sports Medicine Reports published an article entitled “Dog Ownership and Dog Walking to Promote Physical Activity and Health in Patients” (1). In this article, the author, Jacqueline Epping, stated that to combat the national physical inactivity epidemic, “effective population-level strategies are needed to promote activities that are practical, accessible, and sustainable and that can reach a large proportion of the population” and that “dog walking may be such a strategy.” The current article, which summarizes a tutorial lecture given at the 2018 American College of Sports Medicine’s Annual Meeting, aims to 1) substantiate Epping's argument for dog walking as a highly practical approach to physical activity (PA) promotion from a contemporary behavior change science perspective, 2) provide an overview of the state of the dog walking science, and 3) discuss key unanswered questions in the field and ways to address them.
The Rationale for Dog Walking as a Physical Activity Promotion Strategy
A person's PA level is determined by both personal and environmental factors. The focus of this discussion is the personal (individual) level. To date, individual-level interventions, whether stand-alone or part of a multilevel approach, have been predominately guided by social cognitive theories (2). While many of these interventions have been successful in promoting modest, short-term increases in PA (3), there is growing recognition that approaches better aligned with the basic behavior sciences (e.g., motivation, judgment, decision making) are needed to promote long-term PA maintenance (4–6). For example, dual-process models, champion in the field of behavioral economics (7), have become a leading framework for thinking about ways to promote sustainable PA. These models suggest that humans make most decisions via automatic, nonconscious cognitive processing, particularly when fatigued (8). This basic behavior science insight provides an explanation for the short-lived effects of social cognitive theory-based interventions, which promote behavior change strategies that require effortful, conscious cognitive processing (e.g., self-monitoring PA, scheduling time for PA) (4). Physical activity behavior change theorists propose that positive affect (4,5,9), habit (6,10,11), and identity (12) may be key factors for PA maintenance, and a number of new theoretical models have been put forth to bridge the social cognitive tradition in PA intervention research with this new way of thinking. For example, the multiaction control (M-PAC) framework is a PA-specific model that recognizes reflective processes (e.g., perceived capability) as antecedents of PA intention formation, regulatory processes as key to the translation of intention to behavior (also known as action control), and reflexive processes (e.g., habit) as potential hallmarks of PA maintenance (13). Affective judgments, defined as “judgments about the overall pleasure/displeasure, enjoyment, and feeling state expecting from enacting PA,” are considered key to both intention formation and action control in the M-PAC (13). Basic behavior science also explains that distal goals like “better health” and “disease prevention” are ineffective motivators for long-term health behavior change (14), and that PA should be framed in ways that protect autonomy and align with personal values to provide a sustainable source of motivation (15,16).
Dog walking is a PA modality that fits well with the field's shifting emphasis. First, dog walking serves a purpose beyond “better health” and “disease prevention.” Dog walking is essentially a caregiving behavior, a means by which owners ensure that their dogs' exercise and mental stimulation needs are met. Dog walking also often serves an immediate purpose (e.g., allows the dog to go to the bathroom, reduces unwanted behaviors by allowing the dog to expend energy, etc.). Further, dog walking may be an enjoyable form of PA for many people, as it is inherently performed outdoors and in the company of another being (17–19). For owners that do not enjoy dog walking, perhaps due to nonmodifiable factors, like cold weather, their sense of identity as a responsible dog owner may motivate them to walk daily. This motivation may be driven by a desire to avoid the uneasy feeling caused by cognitive dissonance (20) (e.g., “I love my dog and want to do what is best for him, but I don't walk him”). Finally, dog walking also lends itself well to habit formation. Behaviors that are habitually initiated are performed automatically in response to a situational cue, without the need for effortful cognitive deliberating (10). In theory, these behaviors may be easier to sustain over time as they rely on our default cognitive processing system (type 1). A dog eager for his or her daily (or twice daily) walk can serve as a reliable cue for daily PA. As medium- to large-sized dogs live for 10 to 13 years (on average), this cue has staying power.
Consumer market research suggests that U.S. dog ownership has increased by 29% in the past decade (21) and that an estimated 48% of all U.S. households now own at least one dog (22), making the investigation of dog walking as a means to promote population-level PA relevant and timely. It seems plausible that individual-level dog walking interventions that aim to maximize enjoyment during dog walking, to foster a sense of identity as a responsible dog owner (which includes walking), or that promote habit formation around dog walking could complement ongoing national efforts to create walkable communities (23,24).
The State of the Dog Walking Science
Scientific inquiry into the role of dogs as a source of support and motivation for PA has increased in recent years. To demonstrate this phenomenon, we conducted a PubMed search of relevant articles published from January 1, 2000 to December 31, 2018 (search terms: dog* AND [exercise OR walk* OR “physical activity”], in title/abstract). The search yielded 864 initial results, 107 of which were determined to be related to the effects of dog ownership on PA and/or the human health benefits of dog walking. The Figure highlights the dramatic increase in scientific inquiry beginning around 2006. During this time of increasing interest, a number of review articles have been published (25–30). The results of four recent reviews are summarized below.
In 2013, Christian et al. (26) reviewed the literature published between 1990 and 2010 to examine differences in PA among dog owners and nondog owners and the prevalence of dog walking among dog owners. Their meta-analysis of 17 studies demonstrated that dog owners engage in more walking (d = 0.26) and PA (d = 0.16) than nondog owners. Their descriptive review of 15 studies found that 60% of dog owners walked their dog. In 2015, Soares et al. (28) conducted a meta-analysis of 9 studies published from 1990 to 2012 to determine whether dog owners who walk their dog have greater odds of meeting aerobic PA guidelines (150 min·wk−1) than dog owners who do not walk their dog. They found that 63.9% of owners reported walking their dog and that dog walkers were more than 2.5 times more likely to achieve PA guidelines (odds ratio, 2.74; 95% confidence interval [CI], 2.09-3.60).
Although the findings of these reviews appear to tell a clean, consistent story about the cross-sectional relationship between dog ownership and PA levels (i.e., dog owners are more active than dog owners, dog owners that walk the dog are more likely to meet guidelines than dog owners that do not walk the dog), it is important to note the limitations of the studies included in these reviews. The most obvious limitation of these findings is that they do not provide insight into the direction of the relationship between dog ownership and PA. Although it is plausible that dogs cause owners to be more active, it also is plausible that more active people choose to own dogs. As discussed in the 2013 Christian et al. review (26), only two studies (31,32) have examined changes in PA with the acquisition of a dog (both found increases in self-reported recreational walking). Another limitation is the reliance on self-report measures of PA, which are prone to recall and other biases; only 4 of 17 studies in the Christian et al. review (26) and 1 of 9 studies in the Soares et al. review (28) used an objective measure of PA. Finally, the definition of “dog walker” varies tremendously by study. For example, one study defined a dog walker as anyone that reported three or more dog walks per week (33), whereas another required an individual to report >0 min of dog walking per week to be considered a dog walker (34). In another study, individuals that answered “me” to the question “Who, if anyone, usually walks or jogs with your dog(s)?” were categorized as dog walkers (35). The large heterogeneity in these definitions makes it difficult to feel confident in dog walking prevalence estimates or any statements inferring that dog walking behavior is what causes dog owners to be more active than nondog owners.
In 2014, Westgarth and colleagues (27) published a comprehensive review of dog walking correlates. Using a social-ecological approach, the authors examined physical environment, social environment, personal, and dog-related factors associated with dog walking. The review of 31 studies published from 1990 to 2012 found that accessibility/proximity to walking areas (physical environment), perceived dog exercise requirements (dog-related), perceived support/encouragement from dog for walking (dog-related), sense of obligation to walk the dog (dog-related), and dog owner income (personal) were consistently associated with dog walking. The authors called for greater methodological rigor in future studies, including longitudinal designs and randomized trials that allow for causality inferences, but conclude that the current evidence supports interventions targeting the dog-owner relationship and that provide dog-supportive physical environments to increase dog walking.
Finally, in 2018, Christian et al. (29) reviewed the evidence from longitudinal and experimental studies, as well as studies examining the influence of the physical environment and policy on dog walking behavior. Of the four longitudinal studies reviewed, only two examined changes in PA with the acquisition of a dog (the same two studies included in the 2013 review). Six randomized trials investigated a variety of strategies to increase dog walking among current owners (e.g., joint behavioral weight loss program for overweight/obese owners and obese dogs (36), behavioral intervention to promote family dog walking (37), social cognitive theory-based email intervention (38)). One single-arm trial tested a shelter dog walking program for residents of a subsidized housing unit (39). Most studies included in the review were pilot or feasibility trials, and the authors' primary conclusion was that larger more rigorous trials are needed to provide stronger evidence that dog walking interventions can increase PA. The review of the physical and policy environment studies largely corroborated the Westgarth et al. (27) findings, suggesting that neighborhood built environment features that support general walking (e.g., sidewalks, lighting) also may support dog walking, and that dog-specific neighborhood features, such as the proximity of parks with dog-specific features and areas where dogs can be walked off-leash, also may be important. The authors also point out that dogs can sometimes serve as barriers to PA for both dog owners and nondog owners (30), and that interventions that aim to increase dog walking should promote responsible dog ownership etiquette in public places.
A number of studies published in recent years are moving the field in a promising direction and warrant discussion here. In 2016, McCormack investigated changes in PA performed in two city parks that added off-leash areas (40). The research team directly observed PA performed in the parks before and after (within 1 year) of the modifications and found no increase in the proportion of dog-related activity, relative to other activities such as cycling or jogging, in either park. Given the cross-sectional evidence that parks with dog-supportive and off-leash features support dog walking, the results of this natural experiment are surprising and highlight the need for more experimental research investigating the relationship between the built environment and dog walking behavior. In 2017, Dall and colleagues conducted a case-controlled study to examine the relationship between dog ownership and PA among older adults (41). The researchers matched a sample of dog owners (n = 43) and nondog owners (n = 43) on a range of demographic variables, including age, sex, ethnicity, and socioeconomic status, and measured PA and sedentary behavior using the activPAL monitor. Participants wore the monitor for three 1-wk data collection periods over the course of a year, providing data across broad weather conditions. Compared to nondog owners, older adult dog owners spent an additional 22 min·d−1 walking at a moderate intensity cadence (100 steps per minute), accumulating an additional 2760 daily steps. The authors' careful control of potential confounding variables and use of a the activPAL monitor make this article a strong addition to the literature.
Three other recent studies support this article's argument that dog walking aligns well with the field’s shifting theoretical perspective. In 2017, Liao et al. (42) used ecological momentary assessment (EMA) to investigate whether dog-accompanied PA was associated with positive affect in real time. Seventy-one dog owners responded to EMA survey prompts delivered through a mobile phone app (eight prompts per day, Saturday to Tuesday, across three waves of data) that asked them to report what they were doing before the beep went off and to rate their affective state (e.g., “happy,” “calm/relaxed,” “stressed,” “sad/depressed”). The researchers found that greater positive affect was reported during dog-accompanied PA compared to PA performed without a dog (β = 0.56, standard error = 0.25, P = 0.03). This study provides evidence that being active with one's dog may make PA more enjoyable, which strengthens the rationale for dog walking as a potentially sustainable form of PA that deserves continued attention in intervention research. Also, in 2017, Westgarth and colleagues (43) conducted a qualitative study with 38 dog owners to investigate motivators and valued outcomes of dog walking behavior. Dog owners in this study described dog walking as enjoyable and relaxing and explained that the enjoyment stemmed largely from knowing their dog was enjoying the walk. Improved mental well-being was the primary valued outcome of dog walking. In 2016, Rhodes and Lim (44) applied the multi-action control framework with a sample of dog owners to examine the dog walking intention-behavior gap, and factors that explain the successful translation of dog walking intention to action, including affective judgments, habit, and identity (personal standards for dog walking behavior). In this sample (n = 237), 73% of owners reported an intention to walk the dog daily. Forty-five percent of these “intenders” reported not walking daily, and most reported walking <50% of the days they intended. Affective judgments, habit/automaticity, and use of behavioral regulation strategies around dog walking differentiated between nonintenders, unsuccessful intenders, and successful intenders (e.g., successful intenders reported greater affective judgments than unsuccessful intenders, who reported greater affective judgments than nonintenders). Identity and dog size distinguished between unsuccessful and successful intenders (i.e., owners that scored higher on the role identity scale and that had larger dogs were more likely to translate their intentions to action). The authors acknowledged that their measure of dog walking identity may overlap with the sense of obligation correlate observed in previous research (27). Although this study was cross-sectional and used a self-report measure of PA, the direct application of the multi-action control framework to dog walking behavior provides key insights for intervention design.
It also should be noted that, given increasing recognition of the health risks of too much sitting, three recent studies have examined dog ownership in relation to sedentary behavior. In an epidemiological investigation, Garcia et al. found that dog ownership was associated with a lower likelihood of being sedentary for ≥8 h·d−1 (45). In two separate studies with older adults, dog ownership was associated with an average of 21 fewer minutes of sedentary time per day as measured by Actigraph accelerometers (46) and with fewer sitting events (but not less overall sitting time) as measured by activPAL monitors (41). To our knowledge, no interventions have attempted to leverage the human-dog bond to reduce sedentary behavior.
Moving forward, there are two primary research questions relating to the role of dogs in supporting and motivating PA that must be answered. First, do dogs cause their owners to be more physically active? The gold standard study design for determining causality is the randomized controlled trial. As it is not ethical to randomize dog ownership, the causality question might be best answered by recruiting individuals that are planning to acquire a dog and measuring their PA levels before and after dog acquisition while also collecting PA data from a carefully matched control group. It will be critical to include long-term follow-up assessments to examine whether any increases in PA are maintained, and to collect data on plausible determinants of dog walking maintenance, including affective judgments around dog walking and the extent to which dog walking is initiated habitually. As cultural factors and geographic region may affect dog walking norms, multisite trials with diverse samples are needed. These prospective studies will ultimately tell us whether getting a dog leads to sustainable increases in PA without additional intervention.
Rigorous scientific evidence demonstrating that dogs cause their owners to engage in more PA could support programs and policies that make dog ownership accessible to more people. For example, many rental communities do not allow dogs or have restrictions based on size and/or breed. State and local governments can provide incentives to rental communities that welcome dogs and that evaluate them based on their training and temperament, rather than size and breed (47). As more than one third of all U.S. households are headed by renters (48), these changes could impact a large percentage of the American population. These findings also could support the dissemination and implementation of programs that support dog owners in underserved communities, such as The Humane Society of the United States' Pets for Life program (49) and Durham, NC-based Beyond Fences (50). These programs recognize lack of veterinary services in underserved communities as a social justice issue and bring free services (e.g., spay/neuter, vaccinations), supplies, and information to pet owners living in poverty.
The second major research question involves promoting PA through dog walking interventions. This question has two parts. First, can we design interventions that lead to sustainable increases in dog walking among current owners that do not walk regularly? Irrespective of poor estimates of dog walking prevalence, the percent of Americans meeting aerobic PA guidelines is low (51), and levels of dog ownership are high (22), which means opportunity for intervention (at first glance this point seems to obviate the need to investigate the causality question, but it is possible that dog acquisition causes increases in PA that do not fully satisfy guidelines). Pioneers of the field have already completed pilot work that can be built on. As discussed earlier in this article, dog walking also inherently lends itself well to new approaches that aim to promote enjoyable PA experiences, habitual engagement in PA, and engagement in PA that serves a purpose and aligns deeply with one's values. Like all forms of PA, dog walking behavior is influenced by many factors beyond the individual, and community-, environmental-, and policy-level initiatives that support dog walking will complement individual-level interventions. If, overtime, successful interventions are scaled up and implemented nationwide, this should (theoretically) lead to a stronger causal relationship between dog acquisition and PA (question 1).
The second part of the dog walking intervention question relates to a less obvious target audience. Can we design interventions that leverage the human-dog bond to promote PA among nondog owners? According to The Humane Society of the United States, 6 to 8 million cats and dogs enter animal shelters each year (52). Of this 6 to 8 million, 3 million are euthanized. We are in the midst of a mainstream animal welfare movement that aims to increase shelter pet adoptions (53–55) and may provide unique opportunities for novel PA interventions. Because shelter intake numbers and euthanasia rates vary dramatically by state/region (56), these opportunities also will vary by state/region. In some parts of the United States, shelters are filled with dogs that need to be cared for and exercised by volunteers. Foster volunteers also are needed to make room in the shelters for more dogs. In other parts of the United States, foster-based dog rescue organizations import homeless dogs from the overpopulated parts of the country. These organizations do not have brick-and-mortar shelter facilities to hold dogs; all dogs stay in foster homes until they are adopted. The more foster volunteers these organizations have, the more dogs they can rescue. It seems plausible that increasing involvement with the shelter pet social movement could lead to increases in PA, whether it be through offering dog walking programming at local shelters or by promoting fostering (which, in theory, would involve regular walking). Like interventions targeting current owners, these approaches could be designed to strongly align with contemporary behavior change science. Interventions involving shelter dogs lend themselves especially well to stealth approaches that focus on the social contribution (a much more powerful motivator than “better health” and “disease prevention”) and increase PA as a side effect (16,57). Only one published research study, to our knowledge, has used walking shelter dogs as a strategy to promote PA (39).
Longitudinal observational studies and experimental trials should use mixed methodologies to assess changes in PA. Accelerometers can corroborate self-report accounts (which are needed for context) and can provide insight into the absolute intensity of any changes in PA. While dog walking may be a mostly moderate-intensity activity for some dog owners (58), it could be a light-intensity activity for others (based on health and demographic characteristics of both the owner and dog). While there is mounting evidence of the health benefits of light-intensity PA (59,60), it will still be important to characterize dog walking intensity to determine whether an increase in dog walking behavior aids owners in achieving PA guidelines (i.e., 150 min·wk−1 of moderate-intensity PA).
Finally, it is important to note that efforts to increase PA by leveraging the human-dog bond benefit both people and pets. Whether they aim to increase housing options for renters with dogs, provide veterinary services for low-income dog owners, increase volunteer involvement with the shelter pet movement, or directly promote dog walking, these interventions align with the goals of One Health, a global initiative to link human, animal, and environmental health (61). The mutual benefit to humans and animals means the opportunity for novel collaborations between human health experts and experts in the animal health and animal welfare communities.
In her 2011 review paper in Current Sports Medicine Reports, Jacqueline Epping identified dog walking as a practical, accessible, highly sustainable form of PA with great relevance to population-level PA promotion efforts. With this article, we hope to have bolstered Epping's argument by demonstrating that dog walking fits well with contemporary thinking on how best to promote sustainable PA. Although a strong fit in theory, more studies are needed to confirm that positive affective judgments and strong habits around dog walking, as well as dog walking identity, predict dog walking behavior. We also have summarized the dog walking literature to date and demonstrated that dog walking research studies are increasing in number and in rigor. Moving forward, it will be important to determine whether getting a dog causes increases in PA (without any additional intervention). Evidence supporting a causal link between dog acquisition and higher PA levels (among other health benefits) could inform policies and programs that make dog ownership accessible to more Americans, including individuals living in underserved communities. And finally, given the high prevalence of dog ownership combined with the mainstream animal welfare movement to find homes for all adoptable shelter pets, there are extensive opportunities to design and test scalable, multilevel interventions to increase population-level PA via dog walking.
The authors declare no conflict of interest and do not have any financial disclosures.
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