Levels of physical activity (PA) among cancer survivors are low, yet PA may ameliorate effects of treatment (Phillips et al., 2014). We focus here on PA following the most intensive form of cancer treatment, hematopoietic cell transplantation (HCT), with multiple sequelae including graft-versus-host disease and cardiovascular and pulmonary complications. PA is diminished post-transplant (Hacker & Mjukian, 2014; Morishita et al., 2017). This decrease is associated with poorer physical functioning (Bennett et al., 2016), in turn associated with greater mortality (Wood et al., 2016). Moderate exercise has been deemed safe for HCT patients (Wiskemann et al., 2014), and PA interventions feasible (Hacker & Mjukian, 2014). Findings regarding efficacy are mixed, largely due to heterogeneity of intervention components and outcomes (Liu et al., 2009; Persoon et al., 2013). All PA interventions in the HCT setting have focused entirely on patients, ignoring an opportunity to synergistically engage and benefit the caregiver, a 24/7 role requiring provision of medical, logistical, and emotional support. Distress is common among HCT caregivers and their own health promotion is neglected (Applebaum et al., 2016). In addition, the patient-caregiver relationship can be compromised, and communication patterns disrupted (Langer et al., 2009). Guided by interdependence (Kelley et al., 1983) and communal coping (Lyons et al., 1998) perspectives, our 8-session PA intervention provides training in communication skills and behavior change techniques to help patient-caregiver dyads support one another in PA. Previous testing with a sample of breast cancer and prostate cancer survivors and caregivers demonstrated feasibility, but relied solely on self-reported PA and self-determined PA goals (Porter et al., 2018). We have adapted this protocol for HCT and will use a wearable device, a Fitbit tracker, to objectively monitor PA and to provide participants with weekly individualized step goals.

Specific aims are to: (1) determine feasibility of adherence to a dyad-based PA intervention (# of sessions attended and Fitbit wear adherence) for HCT recipients and caregivers (15 dyads) using a single-group pre-post design; (2) determine acceptability of the intervention (dimensions of treatment satisfaction); and (3) describe patterns of change in PA and communal coping from baseline to follow-up. Findings will inform the design of a randomized controlled trial to test efficacy of the intervention to improve physical endurance and relational well-being.

Inclusion Criteria - Patients:

• Scheduled to receive an autologous or allogeneic HCT.
• Being married or in a committed cohabiting relationship.
• English speaking and comprehending.
• Physician approval to participate in a walking program.

Inclusion Criteria - Caregivers:

• Married to or in a cohabiting relationship with the patient.
• Able to participate in a walking program.

Exclusion Criteria - Patients:

• Not scheduled to receive an HCT or already post-HCT.
• Unmarried or not in a committed cohabiting relationship.
• Non-English speaking and comprehending.
• Not medically approved to participate in walking program.
• Enrolled in competing behavioral intervention.

Exclusion Criteria - Caregivers:

• Not married to or partnered/ cohabiting with the patient.
• Unable to participate in a walking program.