Many cancer survivors suffer from long-term side effects well beyond treatment such as fatigue, depression, muscle loss, which contributes to poor quality of life (QoL). Physical activity (PA) has a positive impact on clinical outcomes including improvements in overall QoL, cancer-specific mortality, and reducing treatment-related toxicities. Despite these benefits, the majority of cancer survivors, like their non-cancer counterparts, are not meeting public health PA guidelines. With COVID-19 restrictions easing, the health impact of the new normal may be long-lasting as cancer survivors have higher morbidity and mortality after contracting COVID-19. However, cancer survivors are realizing that they can receive quality and engaging access to care virtually in real-time to self-manage their symptoms. This represents a unique opportunity to test and deliver distance-based interventions in both clinical supportive cancer care and research trials. Short-term supervised PA programs can improve fitness and participant-reported outcomes in cancer survivors, but PA declines significantly post-treatment and long-term adherence is often low. This may also be due to the lack of available programming and facility-based, supervised programs that are easy to access even when they do exist. To achieve long-term health benefits, behaviour change must be sustained. Behaviour change interventions are complex with numerous interacting components that are often poorly described, especially with regard to how maintenance is defined. This hinders the understanding of intervention components that might facilitate PA maintenance. Behaviour change interventions improve PA over the course of the intervention; however, PA declines are more pronounced as the length of time between follow-up assessments increase. Nevertheless, the inclusion of theoretical components increases the likelihood of behaviour change in these interventions.

Recent PA guidelines for cancer survivors suggest 90 minutes of moderate-to-vigorous PA (MVPA) per week, and at least 2 days of strength training per week to accrue clinical benefits. PA-related benefits are only realized if cancer survivors adhere to and maintain PA. However, 74.8% and 86.1% of cancer survivors are not currently meeting aerobic PA and combined PA guidelines, respectively. Given that cancer survivors face several barriers to engaging in in-person PA (e.g., distance from clinical/community programs, treatment-related side effects ), there is a need to develop and assess the efficacy of distance-based approaches. The quality and effectiveness of distance-based interventions relative to non-telehealth home-based exercise or rehabilitation interventions are still unclear. Theoretical approaches to identifying key motivational outcomes to facilitate the adoption and maintenance of PA are limited. Behaviour change techniques such as self-monitoring, goal setting, social support, and action planning are shown to be effective techniques. Interventions that have used behavioural theory in cancer populations produced the largest overall effect size for behaviour change. However, little is known about which intervention mediators (e.g., behaviour change techniques) are responsible for long-term PA adherence.

The dominant theoretical approach in PA and cancer survivorship studies are social cognitive theories. While informative, theories rarely focus on maintenance through enacting on intention-behaviour gap mechanisms. The Multi-process Action Control (M-PAC) framework has a causal structure where an individual moves from intention formation to adoption of action control and onto maintenance of action control. According to the M-PAC, reflective processes (i.e., instrumental attitudes \[expected benefits from performing PA\], affective judgements \[expected pleasure from performing PA\], perceived capability \[one's ability to perform PA\] and perceived opportunity \[perceived social/environmental circumstances to perform PA) are necessary for PA intention formation in cancer survivors. When these expectations are strong and positive, they culminate in the formation of PA intention (i.e., decision to enact regular PA). The dominant determinant when beginning regular PA is marked by the enactment of regulatory processes. Regulatory processes represent the behavioural, cognitive, and affective regulation strategies (e.g., planning, monitoring, attention focus) that are enacted to translate intention into PA. Finally, reflexive processes (i.e., habit \[learned cue-behavior associations\] and identity \[role self-categorization\] are those constructs that develop as a consequence of repeated successful behavioural outcomes over time. Therefore, while the M-PAC represents reflective, regulatory, and reflexive processes that build upon each other over time, each is expected to have some mediated feedback onto PA along with their own independent effect. Taken together, behaviour change is the product of reflective, regulatory, and reflexive processes that have facilitated an initial intention into successful on-going behaviour.

This proposal will address gaps in the PA maintenance literature to demonstrate: (1) changes in absolute values across behavioural performance of cancer survivors, (2) an increase in their magnitude of effect on PA over time; and (3) sex and gender differences in PA maintenance.