Abstract Introduction With increasing numbers of Australians living with a diagnosis of colorectal cancer (CRC), there is increasing interest in the role of physical activity (PA) in reducing the incidence of this disease and helping CRC survivors to recover a high standard of living following treatment. The overall aim of this thesis was to improve understanding of the role of PA in the prevention and rehabilitation of CRC. This was addressed with a literature review on the relationship between PA and CRC risk in Part One and a literature review and intervention relating to exercise rehabilitation for cancer survivors in Part Two. Literature Reviews The aim of the first systematic review was to evaluate the strength of the relationship between PA and CRC risk (Part One). This review followed the Cochrane Data Extraction Guidelines for Non-Randomised Studies, and the data were analysed using the methods utilised by the World Cancer Research Fund. Overall, heterogeneity in the results from all studies and from the ‘highest-quality’ studies was evident. The current state of the evidence of an association between PA and CRC risk was found to be insufficient to claim a convincing relationship exists. However, the totality of the evidence for an association is promising, particularly for the outcome of colon cancer. The second systematic review summarised evidence of benefits from exercise interventions during cancer rehabilitation (Part Two). This review included studies evaluating an exercise intervention for cancer survivors within 12 months of completing chemotherapy. These studies were identified through a systematic search of databases. Data relating to study design, population and outcomes were extracted, and the methodological rigour of each study was evaluated using a structured rating system. As with the first review, there was substantial heterogeneity among the included studies, this time in study and intervention design, which limited the ability to synthesise the data. However, the initial evidence suggests that exercise programs are feasible and may provide a range of benefits to cancer survivors after treatment completion. Pilot study of an exercise intervention for CRC survivors The ImPACT Program (“I’m Physically Active after Cancer Treatment”) was an exercise intervention developed for this study. The program was designed for CRC survivors who had completed chemotherapy within four weeks of baseline testing. The feasibility and efficacy of the program was evaluated through a pilot study. The exercise program involved three supervised aerobic exercise sessions per week for 12 weeks and was evaluated using a one group pre-test post-test design. Both process and an outcome evaluation were conducted. Outcomes were measured at baseline, mid-intervention, intervention completion (12 weeks) and 6 weeks post-intervention. Measures of feasibility (recruitment, retention, adherence, compliance and safety) and efficacy (changes in fatigue, quality of life, physical functioning, and physical activity levels) were included. On completion of the program qualitative data were collected from all participants through one-on-one structured interviews. The main findings were that recruitment was challenging (only 10 participants were successfully recruited); retention and adherence rates were high; however, compliance with the exercise prescription was unexpectedly low. Overall the program was found to be safe and feasible. Participants experienced statistically and clinically significant improvements in fatigue, quality of life, physical functioning and physical activity levels. Key findings from the qualitative analysis were that most participants experienced improvements in treatment symptoms, and that interactions with the exercise trainer, and the flexible program delivery were important aspects of the intervention. Frustrations included scheduling conflicts and a lack of a transition out of the programme. The results of the ImPACT Program provided promising evidence of the feasibility and efficacy of exercise rehabilitation for CRC survivors. Conclusions These findings add to the body of literature on the role of PA in the prevention and rehabilitation of CRC. The literature reviews provided new insight into the state of the evidence for a relationship between PA and CRC risk and the benefits of exercise interventions for cancer survivors during rehabilitation. Conclusions from both literature reviews were limited due to the heterogeneity in study results and study designs, as well as methodological limitations of the included studies. However, the initial evidence was promising for a relationship between PA and reduced CRC risk and for the feasibility and efficacy of exercise for cancer survivors during the rehabilitation period. Future studies with rigorous study design are now required to advance the fields. The results of the pilot study of the ImPACT Program suggest that recruitment is challenging. However, once participants were recruited, retention was high, as was adherence to the exercise program. The feasibility and efficacy results provided promising evidence of the benefit of the exercise program for CRC survivors, and the qualitative results indicate that CRC survivors perceived benefits from exercise offered immediately after treatment and appreciated the individual attention from program staff. The results indicate directions for the implementation of future exercise programs and studies with this population.