Background

Authoritative sources have put forth guidelines for physical activity for cancer survivors [1,2,3], but most do not meet recommended levels [4]. Existing intervention approaches may not be ideally suited for addressing this pressing public health challenge. Physical activity interventions in cancer survivors have tended to produce small effect sizes for physical activity initiation [5], and mixed results for increasing long-term physical activity adherence [6]. Only a few behavior change techniques (BCTs) reliably predict physical activity outcomes (e.g., establishing outcome expectations) [5]. Further, one of the most commonly used BCTs, prompt barrier identification (defined as “identifying barriers to performing the behavior and planning ways of overcoming them” [7, 8]), has been shown to negatively predict physical activity outcomes in cancer survivors [5].

While identifying planning ways of overcoming salient barriers may be useful for increasing physical activity in some contexts, it appears that this approach may be limited in the context of increasing physical activity for cancer survivors. This may be due in part to the nature of cancer survivors’ barriers to physical activity. In addition to the barriers encountered by the general population (e.g., lack of time and motivation), cancer survivors can also face marked internal barriers to physical activity attributed to cancer and its treatment. These can include fatigue, pain, and frustration due to physical limitation and decreased physical functioning [9,10,11,12]. Increasing physical activity in the presence of challenging internal barriers such as these may require a different approach than the standard approaches taken by most current physical activity interventions.

Acceptance- and mindfulness-based approaches to physical activity promotion may be a better fit for cancer survivors. Acceptance- and mindfulness-based approaches to behavioral intervention are often derived from acceptance and commitment therapy (ACT) principles. ACT is a mindfulness-based psychotherapy modality that posits that attempts to willfully alter difficult thoughts, feelings, or sensations are often counter-productive [13, 14]. Instead, ACT emphasizes the importance of living with psychological flexibility. Psychological flexibility is the ability to be aware of, accept, and proceed with gentle persistence despite uncomfortable sensations, thoughts, and feelings that may accompany behaviors consistent with personal values. ACT holds that six core processes facilitate psychological flexibility (Table 1), and has been identified as a promising approach for addressing the unwanted internal experiences that may accompany psychological challenges stemming from cancer diagnosis [15, 16]. Emerging evidence suggests that interventions centered on ACT processes, typically involving face-to-face instruction, may be effective for physical activity promotion to insufficiently active adults [17].

Table 1 Definitions of six core ACT psychological processes
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There has yet been limited research to investigate the use of electronically delivered acceptance- and mindfulness-based approaches to physical activity promotion for cancer survivors. It is unknown to what degree this approach to physical activity promotion would be perceived as relevant and appropriate by cancer survivors, and to what degree such content may be meaningfully administered electronically to this population. The aim of this study was to investigate the potential utility of an acceptance- and mindfulness-based physical activity intervention (the ACTive Program) in a sample of insufficiently active breast cancer survivors.

Methods

Intervention

This study was a non-randomized trial study design centered on obtaining qualitative data on a novel behavioral intervention. The behavioral target of the intervention was to gradually increase moderate-to-vigorous intensity aerobic physical activity and muscle-strengthening physical activity in insufficiently active breast cancer survivors with the goal of meeting the nationally recommended guidelines [18]. The ACTive Program was derived from ACT training experience, existing literature [13, 19], and the Mindful Steps manual (which codifies essential ACT concepts, metaphors, and exercises in the context of physical activity promotion for insufficiently active adults) [20]. The ACTive Program consisted of nine modules. Modules were sent weekly and included narrated videos with visual aids (e.g., didactic videos covering ACT processes), audio files (e.g., mindfulness exercises), images, text, and accompanying documents and email/text messages presenting techniques for ACT processes (see Table 1). Each module contained electronic workbook-type activities that encouraged participants to personally reflect on lesson content and apply the material to their own lives. All intervention content was delivered to participants electronically via secure REDCap (Research Electronic Data Capture) surveys.

Recruitment

Inclusion criteria included being female; ever having had a diagnosis of breast cancer (any stage); having completed primary cancer treatment; and owning a smartphone or a computer with Internet access. Exclusion criteria included currently undergoing chemotherapy or radiation as primary cancer treatment; planning or preparing for surgery as primary treatment or as a reconstruction procedure in the next 3 months; reporting a modified Physical Activity Readiness Questionnaire (PAR-Q) score indicating that physical activity may not be safe, and engaging in ≥ 150 min/week of moderate-intensity aerobic exercise, ≥ 75 min/week of vigorous-intensity aerobic exercise, or an equivalent combination as measured by the Godin Leisure Time Exercise Questionnaire [21].

Participants were recruited via the Dr. Susan Love Research Foundation’s Love Research Army®. This organization distributes recruitment material to a large electronic mailing list comprised of individuals in the USA who have indicated a general interest in receiving information about opportunities to participate in breast cancer-related research. Additional participants were similarly recruited via email from support groups and previous studies at the University of Texas MD Anderson Cancer Center.

Individual interviews

MR conducted semi-structured individual interviews with participating breast cancer survivors after they completed the intervention. Interviews took place between April and September 2020. The interviews were conducted via telephone with the assistance of an interview guide and were between 30–60 min in length. All interviews were audio recorded and professionally transcribed verbatim.

Qualitative data analysis

Three coders (MR [a graduate student with training in health promotion and behavioral science-related research], YL [a university faculty member with training in health promotion and behavioral science-related research], and SF [an undergrad with work experience in health promotion and behavioral science-related research]) conducted template analysis on interview transcripts [22, 23]. Template analysis is a type of thematic analysis that combines flexible, directed hierarchical coding with a relatively high degree of structure. Each coder independently assigned codes to discrete points made by interviewees. These codes were both deductive (derived from the semi-structured interview guide) and inductive in nature (unanticipated themes that emerged during discussion). The coders synthesized all data into an analytical template which outlined major themes and subthemes [22, 23]. The coding team met regularly throughout the course of conducting the analysis to engage in consensus-building for code assignment and to continuously refine the codebook, themes, and subthemes, relationships between the codes, and our notions of the overarching structure of study data. Qualitative data analysis was performed using Dedoose qualitative data analysis software (Version 8.3.35, Los Angeles, CA).

Results

Participant characteristics

This study took place in the context of sweeping “Stay-at-Home” orders enacted by state governments in March and April to curb the spread of COVID-19. We recruited 30 participants. In total, 28 participants completed the baseline survey and received the ACTive Program content. Of those, 16 engaged in an in-depth individual interview. The mean age of the final sample was 58.4 years (SD = 13.8, range 28–82) and the median time since breast cancer diagnosis was 5 years (interquartile range, 4–9). The sample was relatively well educated (50.0% college graduates), mostly non-Hispanic white (77.8%), and mostly overweight or obese (58.8%, Table 2). We did not observe a statistically significant difference between those who completed the study and those who did not in time since breast cancer diagnosis or any of the participant characteristics presented in Table 2 (all p >  = 0.250). There was a trend such that those who withdrew or were lost to follow-up tended to be younger than those who were not lost to follow-up (W = 48.5, p-value = 0.100).

Table 2 Participant characteristics (N = 16)
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Themes

We identified two overarching themes pertaining to the relevance and potential utility of electronically delivered acceptance- and mindfulness-based approaches to physical activity promotion in insufficiently active breast cancer survivors. These were (1) barriers to physical activity adherence and (2) utility of acceptance- and mindfulness-based principles and processes for physical activity promotion.

Barriers to physical activity adherence

Participants discussed numerous barriers to living a physically active lifestyle and reported facing marked challenges due to cancer treatment and diagnosis. For some of these barriers, like uncertainty about how to rehabilitate injuries or how to safely engage in physical activity with lymphedema, participants expressed a need for direct, instrumental support. Related, participants perceived there to be a gap in guidance for how they might transition to living a physically active lifestyle after the completion of their primary treatment. One participant said:

I had a double mastectomy and the DIEP flap reconstruction and there's very little out there that shows me, okay, how do I regain my arm strength… for the mastectomy or in even people who have lumpectomies, I think there's a loss in the chest area that we've looked to fulfill and maybe something geared towards that might help. [ACT021, age 47]

Participant identified other barriers, however, for which actionable solutions were not forthcoming. These included anxiety, depressive symptoms, fatigue, lack of motivation for physical activity, lack of finding physical activity enjoyable (including finding it boring and/or physically unpleasant), and having other responsibilities that took precedence (e.g., family caregiving responsibilities). When asked about what gets in the way of exercising, one participant shared:

I think sometimes when the hind brain gets in and it's like, ‘It doesn't matter’, when you start feeling down and whatever else, you just want to be slightly depressed and curl up and not do anything at all. [ACT054, age 54]

Acceptance- and mindfulness-based principles and processes for physical activity promotion

Participants indicated that they valued their experience with ACTive Program content and that they thought its approach to physical activity promotion intervention would be useful for breast cancer survivors generally. They reported that they found the featured content and techniques to be inherently interesting, unique, and empowering. We present sub-themes that correspond to the ACT principles of acceptance and defusion, mindfulness, and values and goal setting.

Acceptance and defusion

The acceptance- and defusion-based processes struck a particularly resonant chord. One participant said:

...it was a different way of framing [exercise] like, ‘Okay, yeah, it hurts, or you're tired or you don't want to do it, or you're lazy. You'd rather play a game or something…that’s what you're feeling…You don't have to fix it.’ You just have to acknowledge it and then say, 'I'm going to do it [exercise] anyway. [ACT054, age 54]

Acceptance was often discussed in terms of challenges linked to physical activity, such as guilt associated with not being sufficiently active or dissatisfaction about current states/abilities. In this context, many participants reported that the program’s invitation to have the user regard her status with acceptance, rather than as an outstanding problem, was deeply empowering. One participant stated:

And the words though about be kind to yourself, this is your journey, be gentle and kind. Wow. I never saw it in writing to give myself permission to be gentle and kind to myself. I mean, as old as I am, you think, ‘Do it, get the house clean. Do this.’ and just be hard on yourself and be your own sergeant, like a drill sergeant. And I thought, ‘Well, that's not really working. Let's try this. Let's try the gentle and kind, like you would treat a highly-prized friend.’ You wouldn't be, ‘Go clean your kitchen, get the bathroom clean.’ No, you don't talk to other people like to yourself, so why would you talk to yourself like that? So it changed me, it really did. [ACT055, age 62]

The ACTive program content featured many commonly used ACT metaphors. Participants highlighted some of these as being especially useful, and some as needing revisions for appropriateness in a survivorship context (Table 3).

Table 3 Comments on specific ACT devices applied to physical activity promotion for insufficiently active breast cancer survivors
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Contact with the present moment

While most participants’ initial motivation to participate in the study was to increase physical activity (and/or to help others), participants communicated that the mindfulness aspect of the program turned out to be a highly valued feature.

…it was exactly what I needed, every part of it. And I think especially the parts where there was actually time in there for a mini-meditation or a mindfulness section where we sat quietly and you guided it, it was amazing for me. That kind of thing really changes my thought processes and the way my brain works, apparently. So that was really important for me and I never really thought about adding the mindfulness to my walking, that's what I'm trying to start out with is walking and adding that and living in the moment is huge, it changes everything. [ACT018, age 55]

For some participants, mindfulness practices imbued bouts of physical activity with a sense of enjoyment:

So I can go out and walk, but when I'm more mindful, I just seem to get more out of it. I was just doing it like a chore before, when I did walk and think about my grocery list for Kroger and all that. And now I think, ‘I'm holding my head up. I'm enjoying scenery, I'm relaxing. My adrenal stress hormones are subsiding. I'm zenning it, man. [ACT055, age 62]

One participant, who shared that she felt the program overall was not a great fit for her, said that she valued the ability to use mindfulness to appreciate the larger context in which the physical activity was occurring. She shared:

…even though here I am putting myself through 20 of this and 20 of that [exercises], 20 of this kind of stretches 20 of that kind of leg lift, 20 of... Though I'm putting myself through this rather boring and sometimes difficult routine, everything else is okay. Everything else is just fine. I'm in a room where I like the light, I'm in a room where I like the color of the walls, I can hear the sounds of my neighborhood. It kind of helps in that it puts more of a positive spin on it, so it's less distracting and it is adding a positive spin. [ACT041, age 70]

While the mindfulness exercises were enjoyed by many, some did not find them especially useful. While some participants shared that they appreciated that the program instruction normalized lapses in concentration, frustrations pertaining to difficulty concentrating emerged as an impediment to enjoying this aspect of program content (along with finding the time to engage in mindfulness exercises). One participant, who enjoyed many aspects of the program, shared:

I wasn't a big fan of the recordings for, sit back in a chair, the meditation portions of it. I have a hard time finding quiet time that I could actually spend and pay attention to the entire part. [ACT047, age 39]

Values and goal setting

The ACTive Program was designed to have participants connect the numerous benefits of living a physically active lifestyle to their personally held values and set at least one physical activity-related goal. Some participants found this to be a useful exercise. One participant stated:

I loved how you continually reminded us of our goals and our values. This may be somewhat of a stretch, but if I'm healthy, then my family can be healthy. So no, no, it's not a stretch at all... It's sets your mind of being kind to yourself as a patient, and you're allowed these times, you're allow these moments, you need this time, you need this moment… I'm not taking away from anybody else, I'm actually giving to people. If I'm strong and healthy, then I'm actually giving more to them than if I'm feeling miserable, depressed. [ACT050, age 42]

However, having participants establish a meaningful link between their own personal values and physical activity behaviors generally emerged as a challenge.

I can't remember what I put out for values, but there didn't seem always to be to me a direct link to physical activity… I mean, knowing that increased physical activity is going to make me feel better, it's a positive and it is going to help me accomplish other things that I want to do, but it's just hard to connect them directly, I guess. [ACT040, age 73]

Discussion

The aim of this study was to characterize the relevance and potential utility of acceptance- and mindfulness-based techniques for physical activity promotion with insufficiently active breast cancer survivors. Our results indicated that this approach addressed important needs related to physical activity and related cognitions in this population. We identified two overarching themes from in-depth interviews. These pertained to barriers to physical activity, and the relevance and potential utility of using ACT processes for physical activity promotion.

Our findings are concordant with previous literature that has identified fatigue, pain, physical limitation, and decreased physical functioning as common challenges to physical activity faced by breast cancer survivors [9,10,11,12]. In the present study, some participants reported experiencing a precipitous drop in guidance and support after completion of primary treatment. Participants were often uncertain how to transition into healthy lifestyle behaviors after completion of primary treatment, and how to remedy decreases in physical functioning caused by cancer treatment. Participants reported not finding physical activity intrinsically rewarding, and that they sometimes experienced negative psychological symptoms linked to their cancer that could interfere with their motivation and ability to engage in physical activity.

Our findings also support emerging evidence that indicates that physical activity interventions derived from ACT principles may hold promise [17, 24]. The aim of the intervention developed in the present study was to target ACT processes in the context of living an active lifestyle, and many participants reported that the intervention helped to reframe unpleasant internal experiences linked to physical activity and/or imbued exercise routines with a sense of enjoyment. Intervention content centered on acceptance, defusion, and mindfulness was particularly well received; it was perceived to be useful and empowering, and in some cases occasioned meaningful insights in participants. Further, our findings suggest that acceptance- and mindfulness-based physical activity interventions may be delivered effectively online. This finding comports with evidence suggesting that this population is generally receptive to digital behavioral interventions [25], particularly those that can be accessed via computer [26]. This suggests that the principles and techniques that have garnered considerable success in the realm of psychotherapy may be able to be applied effectively to physical activity promotion and other public health priorities.

One challenge encountered in the present study was the process of leveraging participants’ personally held values for increasing motivation for healthy lifestyle behavior change. While this enterprise was useful to some, to others the link was less clear. Interviews revealed that in some cases participants’ prior associations with the term values may have provided some interference with how the construct was operationalized in the present study (e.g., the term values was sometimes thought to implicate moral and social imperatives that are inculcated by one’s upbringing, rather than freely chosen guiding principles that motivate ongoing actions). It may be that alternate diction (e.g., chosen life directions [19]) and other refinements of the electronic workbook-type activities could lead to greater success. More research is needed to investigate how to facilitate the process of meaningful connections between personally held values and healthy lifestyle behavior changes in the context of scalable interventions.

Study limitations

The findings of this study must be considered in the context of its limitations. The generalizability of this study is limited by its convenience sampling method. The sample recruited was mostly non-Hispanic White and relatively well educated. While we recruited participants who did not meet recommended physical activity guidelines, it may have been that the sample was particularly motivated to increase their physical activity. Further, we recruited participants via electronic means, so they may have tended to be especially receptive to an electronically delivered intervention. The COVID-19 pandemic precluded the use of some recruitment strategies that may have yielded a more diverse sample, but future studies should investigate to what degree findings hold true for more diverse populations. This investigation is further limited by the fact that the principal investigator recruited participants initially, delivered much of the intervention content, and conducted the in-person interviews; although in each interview we made a point of encouraging candid, critical feedback, our results may have been affected by social desirability bias. Another challenge encountered in the present study was a high attrition rate. In the present study, only 60% of those recruited completed the follow-up survey. The high attrition rate may have been impacted by the COVID-19 pandemic; sweeping stay-at-home orders were implemented during the time the first cohort of participants were participating in the study, and the COVID-19 pandemic has impacted individuals’ mental health and ability and desire to participate in research studies [27]. Most participants who were lost to follow-up did not provide information as to why they ceased participating, but the only person who explicitly withdrew from the study indicated that she was no longer able to participate due to having to homeschool her children because of schools closing. Despite the high attrition, it is noteworthy that the study was able to continue without major changes to procedures during these calamitous circumstances. While the pandemic may have altered participants’ physical activity patterns and mental health, participants indicated that the study content was especially timely and helpful.

Conclusions

In conclusion, electronically delivered physical activity interventions based on ACT principles offer promise for insufficiently active breast cancer survivors. This approach may be well received and can address important needs related to healthy living. Given the sometimes private, internal nature of lingering challenges to physical activity that can follow cancer diagnosis and treatment, targeting ACT processes may be especially useful for promoting physical activity in cancer survivors. Future research is needed to expand this research to more diverse populations, refine the digital delivery of ACT-derived intervention content (e.g., for values clarification), and evaluate the efficacy of this approach for impacting physical activity behaviors and their psychosocial determinants.