生物与医学2013bmj.com
男性肌肉力量与死亡率之间的关联（2008）
Association between muscular strength and mortality in men (2008)
进阶 · 约 35 分钟读完前置知识：观察性研究设计、多变量回归与混杂因素、生存分析/死亡率指标
导读
这篇 2008 年发表于 BMJ 的研究，基于一项大型男性队列的观察数据，分析肌肉力量水平与全因死亡率之间的关联，并在回归模型中控制了心肺适能等因素。结果显示力量较强的男性死亡率更低，但研究属于观察性设计，作者只报告了相关性而非因果。
HN 关注点：两点：一是健身圈对'练力量能延寿'的实证兴趣，二是对观察性研究能否推出因果的统计方法论争论。
HN 评论精选
这几条评论里：质疑 1 补充 1 亲历 2
质疑观察性研究无法证明因果，遗传与选择偏倚可能解释这一关联。
要注意，这项研究比较的是'碰巧更强壮'的人，而不是被随机分配去变强的人（比如随机分配训练计划）。Larry Wasserman 有篇很好的文章讲推断因果与关联的区别。研究控制了心血管适能等因素是好事，但遗传和选择偏倚等混杂因素更难排除——比如也许让人更容易长快肌纤维的基因变异本身就有保护作用，没有这些基因的人多练也未必受益。话虽如此，我还是强烈推荐抱石和攀岩，作为不爱去健身房的人增强力量、走向健康生活的方式。
micro_cam查看英文原文
It is important to note that this is a study of people who happened to be stronger, not people who were randomly caused to be stronger (ie by randomly assigning workout routines). Larry Wassermann has a great write up on the distinction with regards to inferring causation vs association here: http://normaldeviate.wordpress.com/2012/06/18/48/ It is good that they attempted to control for things like cardiovascular fitness but on there are also confounding factors like genetics and selection bias that are harder to look at (ie maybe the genetic variants that make it easier to build fast twitch muscles are what has the protective effect and increased strength training won't help someone without those genes). That being said I highly endorse bouldering and rock climbing in general as a way to build strength and move towards a healthy life style for people who don't enjoy typical gym workouts.
补充补充方法论观点：论文措辞诚实，但个体层面的寿命预测仍无依据。
目前这里统计上最敏锐的评论是 micro_cam 的这条，指出本研究并非把受试者随机分配到力量训练，只是随时间观察人群。当然，强壮比虚弱好，而且锻炼除了增强力量之外还可能有额外健康益处，所以没有理由因此不锻炼。但也没有强理由认为你个人测出的力量值就能预测寿命长短，尽管研究做了常规回归来控制其他自变量。简单说，这不是治疗组-对照组的实验设计，因此不能推出因果。作者谨慎地使用了'association'一词（很诚实），也周到地考察了全因死亡率（很用心），但我们仍不知道你我能通过力量训练把个人寿命延长多少。
tokenadult查看英文原文
The most statistically astute comment posted here so far is the top-level comment by micro_cam https://news.ycombinator.com/item?id=5493772 pointing out that the study design here doesn't involve random assignment to strength training of any kind, but rather just observation of the study population over time. Sure, it's a good idea to be stronger rather than weaker. Moreover, it is plausible that exercises that tend to develop strength (as measured in the study) have health benefits above and beyond merely developing strength. There is certainly no reason not to exercise based on this finding. But there is also not a strong reason to predict a longer rather than shorter life from your personal strength measurement, even though the study did the usual kind of regression analysis to control for other independent variables. Simply put, this was not a treatment-control study design, http://norvig.com/experiment-design.html http://escholarship.org/uc/item/6hb3k0nz so no inference of causation is supported here. The authors were careful to write the word "association" (which is honest), and the authors were careful to investigate all-cause mortality in this study population (which is thoughtful), but we don't know yet how much you or I can improve individual lifespan by doing strength-building exercises. AFTER EDIT: The comment by micro_cam, which deserves your upvote for getting me started on my comment, is especially astute because it mentions that this was not a genetically sensitive study design. To answer the question posed in one of the replies this comment received, that will eventually be an issue worth looking at, which sorts of "endophenotypes" gain the most benefit from what sort of exercise. But we are nowhere near that level of precision of investigation yet. The statement about limitations of the study at the end of the submitted article mentions more issues. Picking up on something I learned from the late Richard Feynman's comments on the Challenger explosion investigation, I would like to see a scatterplot of these data displayed over the calculated regression line, to see how much uncertainty still surrounds their model. As it is, the confidence intervals around the death rates for different categories of strength overlap considerably, so there are some strong people with the same mortality risk as some of the weaker people.
亲历亲历：中年开始力量训练后力量提升、膝痛和背痛消失。
我用自由重量做力量训练（计划叫 Stronglifts 5x5）已经约 9 个月了。我刚满 44 岁，从没感觉这么好，现在比以往任何时候都强壮。这个计划只有 3 个简单动作，每周练 3 次，每次 30-45 分钟，所需器械极少。网上很难找到同时讲清练什么、怎么练、怎么吃的可靠信息，这个计划全都覆盖，从空杆开始循序渐进，完全免费，想要私人指导才需付费。我以前膝盖疼，现在不疼了；以前长时间写代码就背疼，现在也不疼了。我真心推荐试试力量训练。
unoti查看英文原文
I've been doing strength training (the program is called Stronglifts 5x5[1]) with freeweights for about 9 months now. I just turned 44, and I've never felt better, and I'm stronger now than I have ever been. The program I use describes 3 simple exercises to do 3 times a week, and each workout takes me 30-45 minutes. Very little equipment is needed. It's hard to find good information about this on the net that covers both what exercises to do, how to do them, and how to eat. This program covers all of that, taking you from lifting an empty bar right on up. It's totally free, with an option to pay if you want personal consultation. I used to have knee pain, and I don't anymore. I used to get a sore back from coding all the time, and I don't any more. I seriously recommend trying strength training. [1] http://stronglifts.com/stronglifts-5x5-beginner-strength-training-program/
亲历亲历警示：中断训练后体重上升并罹患糖尿病，呼吁年轻时就开始保养身体。
我以前玩过业余力量举（巅峰时硬拉 420、深蹲约 340），不得不说举重变强这件事很上瘾。知道它能降低死亡概率就更吸引人了。可惜我和很多人一样'掉队'了，基本停止训练，胖了不少，几年后查出糖尿病，还因糖尿病酮症酸中毒这种危及生命的状况进了医院。教训是：赶紧去健身房举铁，并远离自助餐桌。别像我这么蠢。尤其对年轻人和身体本来就好的人：如果要从'老家伙'这儿听一句建议，就听这句——照顾好身体。20 岁甚至 30 岁时很容易以为不用管饮食和锻炼，一切来得轻松，也很容易给自己找借口不去健身房、多吃一块士力架、多喝几罐可乐。别这样，它迟早会找上你。别等到 40 岁躺在病床上才想'也许我该改善饮食、锻炼一下'。
mindcrime查看英文原文
I used to dabble with some amateur powerlifting (I could deadlift 420 and squat about 340 at my peak), and I have to say, there's something really addictive about lifting weights and getting stronger. Knowing that it can decrease your chance of death makes it even more compelling. Sadly, I, like so many other people, "fell off the wagon" and more or less quit lifting, gained a bunch of weight, and now, a few years later, I find out I'm diabetic and I wind up in the hospital with a life-threatening condition known as DKA. Moral of this story: Get your ass in a gym and lift some weights! And step away from the buffet table. Don't be stupid like me. Especially for the younger folks here, and the people who are already in good shape, if you ever take one bit of advice from an "old guy" take this one: Take care of your body. When you're 20, even 30, it's real easy to assume that you don't have to worry about your diet, about exercise, etc... it all seems to come so easily, and it's SO easy to rationalize not going to the gym, eating that extra Snickers bar, drinking those couple of extra cans of Coke, etc. Don't do it. It will freaking catch up with you, sooner or later. Don't wait until you're 40 and lying in a hospital bed to think "Oh, maybe I should clean my diet up and get some exercise".
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