| Summary: | Background: Self-Determination Theory (SDT) has been used successfully as a model for health behaviour change in weight loss programs buts its effectiveness promoting physical activity (PA) behaviour change in an elderly population at elevated risk of colon cancer has not been tested. This study investigated the feasibility of implementing an SDT approach in this population and provides preliminary evidence of its efficacy for modifying motivational regulation in the short- and long-term. Furthermore, barriers to participation, and characteristics of non-participators were explored. Trial design: This thesis consists of two randomized controlled feasibility trials. Methods: Trial A was called ‘Physical Activity and Risk of Colon Cancer’ (PARC) and trial B was called ‘MOtiVation for Exercise- promoting an active lifestyle after Colorectal Cancer’ (MOVE). Participants in PARC (n=31, mean age 69y [SD=4.9], BMI 29.3 [SD=5.1]) were patients diagnosed with polyps after a screening colonoscopy. MOVE participants (n=28, mean age 65y [SD=8.3], BMI=27.7 [SD=4.6]) were patients diagnosed with colorectal cancer after completion of treatment. In both studies, participants were randomized to either an active lifestyle programme (ALP) (PARC n=17, MOVE n=14) or the standard care group (SC) (PARC n=14, MOVE n=14). ALP received supervised exercise sessions and physical activity counselling workshops during the intervention and SC was encouraged to continue with their usual lifestyle. For PARC the intervention was 6months with a 6 months follow-up and for MOVE the intervention was 3months with 3 months follow-up. Randomization was carried out with a bespoke computer software (nQuery). The intervention facilitator was not blinded to the group allocation. Data were analysed with intention-to treat analysis. The primary outcomes were the feasibility of the intervention in these populations. Secondary outcomes were variables of behavioural regulation, physical activity behaviour, physical capacity (fitness and strength), self-efficacy, intention to exercise, and quality of life. Results: PARC: Overall recruitment yield was 12.1% of eligible participants. Main barriers for participation for time commitment and distance to research site. Attrition post-intervention was 29% and at follow-up 43%. Attendance at the ii supervised exercise sessions was 62% and at the workshops was 53%. Post-intervention, ALP had lower amotivation (P<.01), and higher levels of identification (P<.01), intrinsic regulation (P<.001), relative autonomy index (P<.01), and intention to exercise (P<0.05) compared to SC. Total leisure time activity was higher in ALP compared to SC with a mean group difference of 84 min per week (P= 0.08). At follow-up the differences in behavioural regulation were not maintained. ALP did more physical activity at follow-up than SC, with a difference in mean change for leisure-time PA of 170min (P< 0.05). There were no adverse events during the intervention. MOVE: Overall recruitment rate was 58.3% of eligible participants. The main barriers to participation for time commitment and the travel distance to the research site. Attrition at 3months was 14% and 29% at 6months follow-up. Attendance at supervised exercise sessions was 79% and at physical activity counselling workshops 71%. Post-intervention, ALP was engaging in 98min more walking time physical activity (P< 0.05). Group differences were also observed for body composition with a reduction in body weight (-1.6kg), BMI (-0.04 kg/m2) and body fat (-1.4%) in ALP compared to an increase in these parameters in SC (+1.1kg, +0.5 kg/m2, +0.3%) (P< 0.05). At follow-up differences in PA and body composition were maintained (P< 0.05). No differences were observed for behavioural regulation, self-efficacy, intention to exercise, and quality of life at any time-point. Exercise was deemed safe and there were no adverse events throughout the intervention. Conclusion: Recruitment rates of both trials were poor, but other trials have reported similar low recruitment rates in studies with an elderly population. These are the first studies based on SDT in this population to demonstrate increased physical activity behaviour post-intervention and at long-term follow-up. The findings also suggest that 6months of intervention is successful at evoking changes in behavioural regulation. These findings are comparable to other studies using this model. Larger RCTs are needed to substantiate these findings. The studies were sponsored by the University of East Anglia, Norwich, United Kingdom.
|
|---|
