Institute for Cancer Outcomes and Survivorship, University of Alabama at Birmingham, South Birmingham, AL, USA.
University of Alabama at Birmingham, UAB Comprehensive Cancer Center, Birmingham, AL, USA.
Ann Behav Med. 2018 Nov 12;52(12):999-1009. doi: 10.1093/abm/kay004.
Breast cancer survivors rank fatigue (e.g., decreased vitality) as their number one concern affecting quality of life. Excess adiposity is associated with decreased vitality in breast cancer survivors, yet weight loss intervention trials report inconsistent effects on this parameter.
This is a secondary analysis of the Exercise and Nutrition to Enhance Recovery and Good Health for You trial, in which 692 overweight or obese breast cancer survivors ≤5 years from diagnosis, initiated weight loss interventions, and completed assessments semi-annually for 2 years. Assessments included the Godin Leisure-Time Exercise Questionnaire and the SF-36 MOS vitality subscale as an inverse measure of fatigue. Multilevel structural equation models estimated the direct effects of physical activity on vitality and indirect effects through body mass index (BMI) changes.
Within-person findings show that at assessments with greater physical activity, BMI was significantly lower (B = -0.07, p < 0.001) and vitality was higher (B = 0.22, p < 0.001). However, there was no direct relationship between lower BMI and higher vitality (B = -0.11, p = 0.262) after controlling for the relationship of physical activity with BMI and physical activity with vitality. The between-person indirect effect of physical activity change through BMI change to vitality was significant (B = 0.03, p < 0.001). Participants whose physical activity was above the mean (B = 0.37, p < 0.001) and whose BMI was below the mean (B = -1.05, p < 0.001) were more likely to report greater vitality.
Improvements in vitality are primarily associated with increases in physical activity rather than BMI changes in this trial. Vitality was lower among survivors with higher BMI, although within-individual changes in BMI had no effect on vitality. Physical activity and weight loss share mechanistic links to vitality with physical activity potentially increasing (e.g., in an additive or synergistic manner) the effect of BMI reduction on vitality.
乳腺癌幸存者将疲劳（例如活力下降）列为影响生活质量的首要问题。超重与乳腺癌幸存者的活力下降有关，但体重减轻干预试验报告对这一参数的影响不一致。
这是一项针对超重或肥胖的乳腺癌幸存者（≤5 年诊断后）的锻炼和营养以增强恢复和健康的研究的二次分析，这些患者开始了减肥干预，并在 2 年内每半年完成一次评估。评估包括 Godin 休闲时间运动问卷和 SF-36 MOS 活力子量表，作为疲劳的逆测指标。多层次结构方程模型估计了身体活动对活力的直接影响以及通过体重指数（BMI）变化的间接影响。
个体内发现，在身体活动较多的评估中，BMI 显著降低（B = -0.07，p < 0.001），活力更高（B = 0.22，p < 0.001）。然而，在控制身体活动与 BMI 的关系以及身体活动与活力的关系后，BMI 降低与活力提高之间没有直接关系（B = -0.11，p = 0.262）。通过 BMI 变化到活力的身体活动变化的个体间间接效应是显著的（B = 0.03，p < 0.001）。身体活动高于平均值的参与者（B = 0.37，p < 0.001）和 BMI 低于平均值的参与者（B = -1.05，p < 0.001）更有可能报告更高的活力。
在这项试验中，活力的改善主要与身体活动的增加有关，而不是 BMI 的变化。BMI 较高的幸存者活力较低，尽管 BMI 的个体内变化对活力没有影响。身体活动和减肥具有与活力相关的机制联系，身体活动可能会增加（例如，以附加或协同的方式）BMI 降低对活力的影响。
