Thompson H J
AMC Cancer Research Center, Denver, Colorado 80214.
Cancer Res. 1994 Apr 1;54(7 Suppl):1960s-1963s.
Physical activity is defined as bodily movement due to skeletal muscle contraction that results in quantifiable energy expenditure. Both epidemiological and laboratory data indicate that the level of physical activity in which an individual engages may affect cancer risk. Exercise is distinguished from other types of physical activity by virtue of the fact that the intensity, duration, and frequency of the activity(s) is specifically designed to improve physical fitness. Based on available data, a role for exercise in specifically reducing cancer risk has been conjectured and is referred to as the exercise-cancer hypothesis. However, the amount of scientific evidence in support of this hypothesis is still quite limited, and there are conflicting reports about the nature of the association. The exercise-cancer hypothesis was evaluated in two experimental animal models for breast cancer using treadmill running as the exercise paradigm. The data presented indicate that both the intensity and duration of exercise affect the development of experimentally induced breast cancer. In general, as exercise intensity increased, the likelihood that such physical activity inhibited carcinogenesis increased. Exercise at lower intensities resulted in either inhibition, no effect, or enhancement of the tumorigenic response depending on the duration of exercise. Inhibitory conditions of exercise affected both the initiation and promotion/progression stages of the disease process.
身体活动被定义为骨骼肌收缩引起的身体运动，这种运动导致可量化的能量消耗。流行病学和实验室数据均表明，个体参与的身体活动水平可能会影响癌症风险。运动与其他类型的身体活动的区别在于，其活动的强度、持续时间和频率是专门设计用于提高身体素质的。基于现有数据，人们推测运动在特定程度上可降低癌症风险，这一推测被称为运动 - 癌症假说。然而，支持这一假说的科学证据数量仍然相当有限，并且关于这种关联的性质存在相互矛盾的报道。使用跑步机跑步作为运动模式，在两种乳腺癌实验动物模型中对运动 - 癌症假说进行了评估。所呈现的数据表明，运动的强度和持续时间都会影响实验诱导的乳腺癌的发展。一般来说，随着运动强度的增加，这种身体活动抑制致癌作用的可能性也会增加。较低强度的运动根据运动持续时间的不同，会导致对致癌反应的抑制、无影响或增强。运动的抑制条件会影响疾病过程的起始阶段和促进/进展阶段。
