How effective are fitness trackers in changing the physical activity behaviour of breast cancer survivors?
Creators: name: LYNCH, Christopher
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 420702
subject: Exercise physiology

description: Physical activity is a human behaviour central to the aetiology and management of many cancer outcomes. In survivors of breast cancer, greater physical activity reduces the risk of breast cancer-specific and all-cause mortality, greater physical activity also reduces the risk of further chronic disease and may reduce the risk of breast cancer recurrence. Breast cancer survivors may experience lingering effects from treatment, including prolonged or recurrent bouts of cancer-related fatigue, but being more physically active can reduce the impact of fatigue and improve the health-related quality of life. Therefore, it is crucial to improve the physical activity of insufficiently active breast cancer survivors.

Physical activity and cancer survivorship is a rapidly growing field of enquiry, and many important questions remain unanswered, such as, what are the most effective physical activity behaviour-change interventions for cancer survivors? There is a considerable body of literature that suggests implementing digital technologies in interventions for physical activity can lead to positive short-term changes in behaviour, and a popular consumer device, the fitness tracker, is one such technology. While there is preliminary support for interventions that use mobile technologies to increase physical activity behaviour, the specific efficacy of fitness trackers to increase physical activity is unknown. In special populations, such as breast cancer survivors, continual work is needed that responds to the emergence of popular new technologies that may be harnessed to improve health. Therefore, this thesis aims to investigate how effective fitness trackers are in changing the physical activity behaviour of insufficiently physically active breast cancer survivors. 

Five linked studies have been undertaken in the investigation of how effective fitness trackers are in changing physical activity behaviour. The first study was a systematic review and meta-analysis that synthesised the evidence of how effective fitness trackers are in changing physical activity behaviour among adults. The second study was a cross-sectional examination of the validity of energy expenditure estimations made by fitness trackers during laboratory-controlled treadmill walking and running. The purpose of this study was to enable an informed decision on a suitable tracker for use in an intervention. The third study was a qualitative examination of the acceptance and usability of different fitness trackers among a group of breast cancer survivors. The objective of this study was to determine the features of fitness trackers that would facilitate their use in a behavioural intervention that focused on increasing physical activity. 

The fourth and fifth studies were developed using a group of insufficiently physically active post-treatment breast cancer survivors who underwent a 12-week intervention. The fourth study examined the association of specific cancer symptoms with the level of physical activity before any intervention. This study aimed to observe the relationship between objectively-assessed physical activity and health-related quality of life specifically among insufficiently physically active breast cancer survivors, and how any relationship was changed by breast cancer-specific concerns, fatigue interference, and self-efficacy for physical activity. The fifth and final study examined the effect of a 12-week intervention using a fitness tracker combined with a behavioural counselling and goal-setting session to change the physical activity behaviour of insufficiently physically active post-treatment breast cancer survivors. Secondary aims of the fifth study were to also examine any effect of an intervention on cancer-related outcomes, including health-related quality of life and cancer-related fatigue, as well as self-efficacy for physical activity. The cross-over design of the fifth study enabled the assessment of any maintenance of change in physical activity behaviour for participants in the primary intervention group 12 weeks post-intervention.

Study one concluded that fitness trackers may enhance a physical activity intervention, as a generally positive effect on physical activity outcomes is found when compared to a control. However, there is no evidence of a positive effect on physical activity outcomes when compared to an alternative intervention. These results may be, in part, due to a large diversity of study and intervention characteristics among the 21 studies included in the review. Study two concluded that the estimations of energy expenditure reported by the fitness trackers distinguished between walking and running, with a general increase in the activity outcome as exercise intensity increased, but given their potential bias and error, estimations of physical activity should be interpreted with caution. Two fitness trackers, the Fitbit One and Garmin Vivofit, correlated significantly (p &lt; 0.01; r = 0.702; 0.854) with criterion across all gait speeds (0.70 to 3.33 m·s-1). While fitness trackers may not be suitable as research measurement tools when assessing physical activity, they may be suitable for use in interventions of behaviour-change as they provide feedback to the user on physical activity. In study three, 14 breast cancer survivors participated in qualitatively evaluating a range of fitness trackers. Most participants reported wearing fitness trackers daily during the trial period. Three themes emerged from this study: self-awareness and motivation; confidence and comfort with wearable technology; and, strategies for application. Fitness trackers were perceived as useful and acceptable by breast cancer survivors to use in an intervention. The findings of studies two and three supported the choice of the Garmin Vivofit2 fitness tracker to use in a later intervention. 

Study four found that objectively assessed moderate-intensity physical activity is positively associated with health-related quality of life among survivors of breast cancer with low levels of physical activity but 70 to 75% of the variance in levels of moderate-intensity physical activity was unaccounted for. Breast cancer-specific concerns, fatigue interference, and self-efficacy were not associated with moderate-intensity physical activity. Study five found that intervention using a fitness tracker achieved a mean increase of 4.5 minutes per day of moderate-to-vigorous intensity physical activity, representative of a small-moderate effect (d = 0.34). However, there was concurrent and significant changes in time spent as a proportion of the day in light-intensity physical activity (-8.3%) and in sedentary behaviour (7.9%) (t (16) = 3.522, p &lt; 0.01; t (16) = -3.162, p &lt; 0.01). At the end of follow-up for the maintenance sub-group, moderate-to-vigorous intensity physical activity further increased by 1.2 minutes per day to an overall mean of 23.5 (±9.2) minutes per day. Post-intervention, all health-related quality of life indicators, except for the physical and emotional well-being subscales, increased significantly. Self-efficacy for physical activity also increased significantly (t (16) = -2.385, p &lt; 0.01). At the end of follow-up for the maintenance sub-group, only the Functional Assessment of Cancer Therapy subscales for anaemia and fatigue (including trial outcome indexes) maintained any improvement.  

The conclusion drawn from the findings of the studies included in this thesis is that the inclusion and use of a fitness tracker alone in a physical activity intervention is unlikely to generate any more of a meaningful change in physical activity behaviour than any other physical activity intervention modality. Breast cancer survivors would benefit greatly from increasing physical activity, and the act of intervention alone in this sample, appeared to be of benefit to their health-related quality of life. However, to achieve the health benefit of sufficient physical activity any change in behaviour must be sustained. The evidence in this thesis is inconclusive as to if a fitness tracker is effective in changing the physical activity behaviour of insufficiently physically active breast cancer survivors.

While it is disappointing that the findings of this thesis are inconclusive as to the effectiveness of a fitness tracker in changing physical activity behaviour, it was an important investigation to undertake. It is an early study of the use of fitness trackers and one of the few conducted among insufficiently physically active breast cancer survivors. The findings of this thesis contribute to future studies that will harness the exponential growth in technologies that could change health behaviour. The work in this thesis highlights the importance of assessing psychological, social, and contextual variables, as well as assessing primary outcomes such as physical activity. The work may also contribute to the discussion that advocates the use of alternative evaluation frameworks, as research in behavioural studies and physical activity evaluate digital technologies in interventions.