生物与医学2020bmj.com
五年运动训练对全因死亡率的影响
Effect of exercise training for five years on all cause mortality
入门 · 约 30 分钟读完前置知识：基础统计学、随机对照试验概念
导读
这篇 BMJ 发表的挪威随机对照试验（Generation 100 研究）考察了五年运动训练对 70-77 岁老年人全因死亡率的影响。参与者被分为对照组（按挪威指南每周约 5 次 30 分钟中等强度运动）、HIIT 组和中等强度持续训练（MICT）组，结果显示三组间死亡率差异无统计学显著性（95% 置信区间与风险比 1.0 重叠）。作者指出对照组本身活动水平很高、参与者基线健康状况较好等因素可能影响了检测差异的能力。
HN 关注点：如何正确解读这项'运动不能降低死亡率'的结论：结果不显著不等于没有差异，以及研究设计（对照组也在运动）对结论的影响。
HN 评论精选
这几条评论里：支持 1 补充 3
补充提醒读者结果不显著≠没有差异，并指出对照组活动水平高和选择偏倚削弱了研究检测差异的能力
很多评论声称这项研究证明运动有益健康。虽然我大体同意这个前提，但这并不是本研究结果所显示的。首先，该 RCT 只针对 70-77 岁人群；其次，结果在 p<0.05 水平上不具统计显著性——可视化摘要中 95% 置信区间与风险比 1.0（即组间无差异）重叠。注意，结果不显著并不意味着没有差异！而是说即使存在差异，以本研究的样本量（统计功效）可能也检测不出来。论文的'优势与局限'部分也明确列出了一些可能导致不显著的原因：对照组在整个研究期间活动水平很高，很多人做 HIIT，这可能影响了检测组间差异的能力；此外存在选择偏倚，参与者比未入选者更活跃、整体健康状况更好。基本上，连'对照组'都有很好的基线活动水平，缩小了它与两个干预组之间的运动量差异。
stygiansonic查看英文原文
A lot of comments are claiming this study shows that exercise is good for your health. Though I generally agree with that premise, that is NOT what the results of this study show. The abstract and visual abstract clearly state this. - The RCT was done only on individuals aged 70-77 - Furthermore the results were not statistically significant at p < 0.05. You can see this in the visual abstract where the 95% CI overlaps with risk ratio = 1.0, where 1.0 means "no difference" between the groups. Note that the results being non-stat sig does not mean that there was no difference! It means that the difference, if present, was probably too small to detect given the power (number of participants) included in the study. This is important to understand! Furthermore, in the "Strengths and limitations of this study" they clearly outline some reasons why the results may have been non stat-sig, including: - "Firstly, participants in the control group had a high level of activity throughout the study, and many exercised using HIIT. This might have affected the study’s ability to detect statistically significant differences between groups." - "selection bias might have influenced our results, as participants were more active and had better overall health than non-included participants" Basically, even the "control" group looked like they had a good baseline level of activity, decreasing the activity level difference between that and the two treatment groups. My takeaway from this study is that in isolation, it doesn't provide much evidence for or against the effect of exercise, but taken together with other studies can be used for evidential value. The results can also be used to inform future studies. The authors clearly understood this when they stated in the main measure outcome: "An exploratory hypothesis was that HIIT lowers mortality more than MICT."
补充详解三组设计并指出其真正测试的是'部分运动为 HIIT/MICT'，核心启示是运动形式不重要、坚持才重要
这项研究分三组：对照组遵循挪威现行指南（几乎每天 30 分钟中等强度运动）；HIIT 组与对照组方案基本相同，但每周五次中有两次改为 10 分钟热身加四组 4 分钟、90% 最大心率的间歇训练；MICT 组则是两次改为约 70% 最大心率的半小时稳态运动。结论：对照组、HIIT 组和 MICT 组之间死亡率几乎没有差异。我不太喜欢这个研究设计，因为它其实不是在测试 HIIT（或 MICT），而是在测试'当 40% 的运动是 HIIT（或 MICT）时会发生什么'。不过最重要的启示是：运动对你有好处，而运动的具体形式几乎完全不重要。做你喜欢且能坚持的运动就好。早上只有十分钟就做 HIIT，下班后有一小时想出门就去慢跑或骑车。任何运动都比不动强。
thomascgalvin查看英文原文
This study had three groups: - Control: followed the current Norwegian guidelines, which recommend 30 minutes of moderate level physical activity almost every day - High Intensity Interval Training (HIIT): Generally followed the same program as control, but two of the five sessions were instead a 10 minute warmup, followed by four four-minute intervals, working at 90% max heart rate - Moderate Intensity Continuous Training (MICT): Generally followed the same program as control, but two of the five sessions were instead a half hour of steady-state exercise, at about 70% max heart rate Conclusion: There was little to no difference in mortality between the control, HIIT, and MICT groups. I don't love this study design, because it isn't really testing HIIT (or MICT); it's testing what happens when 40% of your exercise is HIIT (or MICT). That being said, I think the most important takeaway is that exercise is good for you, and what that exercise looks like is almost completely unimportant. Do what you enjoy and can sustain. If you have ten minutes in the morning, do HIIT. If you have an hour after work and want to get out of the house, go jogging or ride a bike. Anything is better than nothing.
支持赞赏研究者发表阴性结果的做法，认为这有助于对抗选择性报告和可重复性危机
虽然这些结果并不算令人印象深刻或有说服力（不会让我想改变自己的运动习惯），但看到研究者愿意发表平淡无奇的结果，而不是只挑有意思的结果发表、把其余的束之高阁，还是令人欣慰的——后者正是社会科学信任危机/可重复性危机的一个重要成因。
bnjmn查看英文原文
Although these results are not exactly impressive or compelling (they don't make me want to change my exercise habits), it's reassuring to see researchers go through with publishing underwhelming results, rather than cherry-picking only the interesting results and sitting on the rest, which is a major contributing factor to the crisis of confidence/replication in the social sciences. - https://en.wikipedia.org/wiki/Cherry_picking - https://www.nature.com/news/scientific-method-statistical-errors-1.14700 - https://fivethirtyeight.com/features/science-isnt-broken/ - etc...
补充称赞可视化摘要这种形式比纯文字摘要信息密度更高、更易读
稍微跑题：我好像以前从没见过'可视化摘要'（Visual Abstract），我挺喜欢的。相比纯文字摘要，它能在同样的篇幅里以更易消化的形式承载多得多的信息。
scythmic_waves查看英文原文
Slightly OT: I'm not sure I've ever seen a "Visual Abstract" before and I kind of love it. You can pack way more information into the same space and in a much more digestible format than a purely text abstract.
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