FOR THOSE in the doldrums(情绪低落，无精打采), few things are more tiresome(令人厌烦的，无聊的) than being told to exercise. But unwelcome advice is not necessarily wrong. Study after study has found that exercise boosts mood(改善情绪，提振心情) and reduces anxiety. Two large analyses published earlier this year go further(更进一步，补充说明), suggesting it works about as well as(和……一样好；以及) therapy or antidepressants.
对于情绪低落的人来说，没有什么比被告知要去运动更令人厌烦的了。但这不受欢迎的建议未必是错误的。一项又一项研究发现，运动能改善情绪、减轻焦虑。今年早些时候发表的两项大型分析更进一步，表明其效果与心理治疗或抗抑郁药大致相当。
The first, published in January by researchers based across Britain and Ireland, took the form of(以……形式出现，采用……形式) a Cochrane review(① 背景：Cochrane系统评价是国际...)—a well-regarded(备受推崇的，评价高的) meta-analysis of health-care research. It pooled(汇集，合并) the results of 69 randomised controlled trials(随机对照试验) (RCTs) conducted to measure the effects of exercise on depression. The second paper, published in February in the British Journal of Sports Medicine, was a so-called meta-meta-analysis(元荟萃分析，对多项荟萃分析的再分析). It drew on(利用，引用) more than 1,000 trials involving nearly 80,000 participants. Both concluded that exercise reduces symptoms of depression and anxiety by roughly as much as conventional treatments.
第一项研究由英国和爱尔兰的研究人员于今年一月发表，采用了Cochrane系统评价的形式——这是一种备受推崇的医疗保健研究荟萃分析。它汇总了69项随机对照试验（RCT）的结果，这些试验旨在测量运动对抑郁的影响。第二项论文于二月发表在《英国运动医学杂志》上，是一项所谓的"元荟萃分析"。它利用了超过1000项试验的数据，涉及近8万名参与者。两项研究均得出结论：运动减轻抑郁和焦虑症状的效果与传统治疗大致相当。
There are important caveats(警告，注意事项). Meta-analyses are only as good as(取决于，与……一样好) the studies they include, and exercise trials are prone to(易于……的，有……倾向) being skewed. For one thing, participants cannot be blinded(设盲（使参与者不知分组）)—they know if they are doing kettlebell swings(① 定义：壶铃摆动是使用壶铃进行的一种全...) or not—which makes their self-reported mood vulnerable to(易受……影响，脆弱) any favourable expectations they might have. For this and other reasons, the Cochrane review judged all the studies it included to be at “high risk” of bias.
有重要的注意事项。荟萃分析的质量取决于其所包含的研究，而运动试验容易出现偏差。首先，参与者无法被设盲——他们知道自己是否在练习壶铃摆动——这使得他们自我报告的情绪容易受其可能抱有的任何有利期望的影响。基于此及其他原因，Cochrane系统评价认定其所包含的所有研究均存在"高风险"偏倚。