Socio-ecological correlates of physical activity in breast and colon cancer survivors 4 years after participation in a randomized controlled exercise trial (PACT study)

Background
Having a physically active lifestyle after cancer diagnosis is beneficial for health, and this needs to be continued into survivorship to optimize long-term benefits. We found that patients, who participated in an 18-week exercise intervention, reported significant higher physical activity (PA) levels 4 years after participation in a randomized controlled trial of supervised exercise delivered during chemotherapy (PACT study). This study aimed to identify social-ecological correlates of PA levels in breast and colon cancer survivors 4 years after participation in the PACT study.
Methods
Self-reported PA levels and potential correlates (e.g. physical fitness, fatigue, exercise history, and built environment) were assessed in 127 breast and colon cancer survivors shortly after diagnosis (baseline), post-intervention and 4 years later. Multivariable linear regression analyses were performed to identify social-ecological correlates of PA 4 years post-baseline.
Results
The final model revealed that lower baseline physical fatigue (β = -0.25, 95% CI -0.26; -0.24) and higher baseline total PA (0.06, 95% CI, 0.03; 0.10) were correlated with higher total PA levels 4 years post-baseline. Higher baseline leisure and sport PA (0.02, 95% CI 0.01; 0.03), more recreational facilities within a buffer of 1 km (4.05, 95% CI = 1.28; 6.83), lower physical fatigue at 4-year follow-up (-8.07, 95% CI -14.00; -2.13), and having a positive change in physical fatigue during the intervention period (0.04, 95% CI 0.001; 0.07) were correlates of sport and leisure PA levels 4 years post-baseline.
Conclusions
This study suggests that baseline and 4-year post-baseline physical fatigue, and past exercise behaviour, were significant correlates of PA 4 years after participation in an exercise trial. Additionally, this study suggests that the built environment should be taken into account when promoting PA. Understanding of socio-ecological correlates of PA can provide insights into how future exercise interventions should be designed to promote long-term exercise behaviour.
Trial registration
Current Controlled Trials ISRCTN43801571, Dutch Trial Register NTR2138. Trial registered on 9 December 2009,
http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2138

背景
癌症确诊后维持身体活动的生活方式对健康有益，且需延续至癌症生存阶段以优化长期健康获益。本研究团队此前发现，在一项针对化疗期间监督式运动的随机对照试验（PACT研究）中，参与18周运动干预的患者，在干预结束4年后的身体活动（physical activity，PA）水平显著更高。本研究旨在探究参与PACT研究4年后的乳腺癌与结肠癌幸存者的PA水平的社会生态学关联因素。

方法
本研究在127名乳腺癌及结肠癌幸存者中，分别于确诊后即刻（基线）、干预后及4年后，评估其自我报告的PA水平及潜在关联因素（如体能、疲劳感、运动史与建成环境）。采用多变量线性回归分析，以识别基线后4年的PA水平的社会生态学关联因素。

结果
最终模型显示，较低的基线身体疲劳（β = -0.25，95%置信区间：-0.26 ~ -0.24）与较高的基线总PA（β = 0.06，95%置信区间：0.03 ~ 0.10），均与基线后4年的较高总PA水平相关。此外，较高的基线休闲与运动类PA（β = 0.02，95%置信区间：0.01 ~ 0.03）、1公里缓冲区内的休闲设施数量更多（β = 4.05，95%置信区间：1.28 ~ 6.83）、4年随访时较低的身体疲劳（β = -8.07，95%置信区间：-14.00 ~ -2.13），以及干预期间身体疲劳的正向变化（β = 0.04，95%置信区间：0.001 ~ 0.07），均与基线后4年的运动与休闲类PA水平相关。

结论
本研究表明，基线及基线后4年的身体疲劳、既往运动行为，均与参与运动试验后4年的PA水平存在显著关联。此外，本研究提示，在推广PA时应纳入建成环境因素。对PA的社会生态学关联因素的解析，可为未来设计以促进长期运动行为的运动干预方案提供理论参考。

试验注册
本研究已在Current Controlled Trials注册编号ISRCTN43801571，荷兰试验注册库（Dutch Trial Register）注册编号NTR2138，注册日期为2009年12月9日，注册链接：http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2138