Increased physical activity reduces cancer risk in humans, but why this whole-organism attribute reduces cancer remains unclear. Active individuals tend to have high capacity to generate energy on a sustained basis, which in turn can permit greater immune responses crucial for fighting emerging neoplasia. Thus, we suggest energetic capacity as a potential mechanism to explain the activity–cancer link, given that humans are intrinsically (not externally) energy limited. Human and rodent studies show that individuals with high energetic capacity mount greater immune responses and have lower cancer incidence; these trends persist after controlling for actual physical activity, supporting a direct role of energetic capacity. If true, exercise efforts might best target those that increase one’s energetic capacity, which may be both individual and exercise specific.

增加体力活动会降低人类患癌症的风险，但为什么这种整体性的属性会降低癌症的风险仍不清楚。活跃的个体往往具有持续产生能量的高能力，这反过来又可以允许更强的免疫反应，这对于对抗新出现的肿瘤至关重要。因此，我们建议将能量作为解释活动与癌症联系的潜在机制，因为人类本质上（而非外部）能量有限。人类和啮齿动物研究表明，具有高能量能力的个体会产生更强的免疫反应，并且癌症发病率更低；在控制了实际的身体活动后，这些趋势仍然存在，支持能量的直接作用。如果是真的，锻炼的努力可能最适合那些增加精力充沛的人，