仰卧起坐的坏处让你吃惊！
BBC克劳迪娅·哈蒙德（Claudia Hammond）(2016年5月7日)
如果你不喜欢花时间做仰卧起坐（卷腹），那这可能对你来说是个好消息。研究者现在不仅仅在争论仰卧起坐是否对人有益，而是它是否还有损身体健康。
仰卧起坐是否能给你带来紧实的巧克力腹肌，还是平坦的腹部实际上是取决于饮食和全身运动而不是一个特定部位的训练？一份仰卧起坐研究报告证据表明，仰卧起坐可以提升肌体灵活性和肌肉力量。屈曲脊柱已被证明有助于营养物质的送达椎间盘，从而有利于防止骨骼僵硬。
到目前为止这份报告看起来还好。但想要拥有马甲线的确需要付出艰苦的努力。2011年，在伊利诺伊州（Illinois）的一个小型的随机对照试验中，1个小组做了每日腹部练习，而幸运的对照组则没有。经过六周的详细测量，研究者们发现仰卧起坐对于腰围和腹部脂肪的面积没有任何影响。
很多运动人士将仰卧起坐作为锻炼的一种方式，来提高自己身体核心区的稳定性。但是印第安纳州立大学（Indiana State University）的托马斯·内赛尔（Thomas Nesser）的研究表明，提高核心区的稳定性不一定等同于运动上会有很好的表现。
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一些人做仰卧起坐天生容易导致背部伤痛。(图片来源: Getty Images)
不管仰卧起坐是否真的能助你实现你想要的体格或健身效果，它们有可能带来意想不到的后果，例如背部疼痛吗？加拿大滑铁卢大学（University of Waterloo）的生物力学脊柱教授斯图尔特·麦吉尔（Stuart McGill）对仰卧起坐已经研究多年，深信传统的卷腹动作会对身体有害。
在脊椎生物力学实验室，他在猪身上已经进行过几十次的研究。通过模仿人做仰卧起坐时的姿势，他不断地弯曲猪的脊椎，一次长达数小时。随后，他检验猪的脊椎盘，发现弯曲时隆起的部位已经被挤压成尖状。如果同样的事情发生人身上，这将压迫到神经，造成背部疼痛，甚至可能是椎间盘突出。
之所以将猪选为实验对象，是因为与其他动物相比，猪的脊椎与人类的脊椎相似度更高。当然，也有反对者指出，人和猪之间仍有许多不同之处。此外，在研究过程中，对猪的脊椎进行弯曲的时间过长。而对于人来说，训练再刻苦，中间也会有休息。
也许这些研究结果只是说明了极端情况下的后果，就像你几乎不可能一直做仰卧起坐，一小时接着一小时，但是在现实生活中，人们并没有因为每次做几组每组15个仰卧起坐就损害了椎间盘。而即便如此，伤害还是有可能会发生。2005年发表的研究驻扎在美军布拉格堡的士兵结果表明，每两年进行一次的军队体能测试中的仰卧起坐环节导致56%的士兵受到身体伤害。
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猪脊骨试验表明类似仰卧起坐的运动会导致椎间盘凸出并引起疼痛 (图片来源: Getty Images)
对于有些人来说，仰卧起坐似乎更容易产生腰背问题。相反，一些人每天都做30个仰卧起坐，坚持了几十年，却没有任何异样。我们可能不知道也很难知道我们是属于哪一类人。它可能源于我们的基因。一篇报告表明大部分的问题并非源于不断的摩损，而是遗传因素。人之所以有或没有背部问题，75%是因为遗传。
自1991年以来，“双胞胎脊柱”（Twin Spine）研究项目已经对芬兰，加拿大和美国多对双胞胎进行过研究。研究人员发现，人背部椎间盘的退变程度很大部分取决于基因。即使双胞胎中的一个干的是体力活，另一个是从事的是久坐不动的工作，但是背部问题的发生概率大致相同。
所以，仰卧起坐可能导致背部疼痛，这样的说法仅适用于一部分人。当然这是不做仰卧起坐的很好借口。但是，若想要平坦的腹肌，有没有一种风险更低的方式？斯图尔特·麦吉尔教授建议，（平躺于地）将双手滑动到下背部，避免下背部直接接触地板。这将最大限度地减少背部压力。弯曲一腿膝盖，而让另一腿伸直。然后将头部和肩部稍稍离开地板。他说，想象你的头正靠在浴室的体重计上，你只需将头抬起，让体重计显示为0就可以。他的《背部机理》（Back Mechanic）一书中对该训练有详细的介绍。
新西兰的奥克兰理工大学（Auckland University of Technology）的布雷特孔特雷拉斯（Bret Contreras）针对仰卧起坐的研究表明，脊柱练习，每组练习应不超过60次，从15次开始，之后可以逐步增加。最后，当我们躺了一整夜或者甚至只是坐了很长时间（中途未站起来），这将使得仰卧起坐练习更艰难，也会增加受伤的风险。鉴于此，长时间坐于桌前后，请不要起身后立马在地板上开始仰卧起坐的训练；早上起床的第一件事也要避免此练习。
（责编：友义）
The surprising downsides of sit-ups
By Claudia Hammond,7 May 2024
If you don’t like spending time crunching your abs then we might have some good news. Researchers are not only arguing over whether sit-ups do you any good – but whether they might even be bad for you.
Do they give you a taut six-pack across your abdomen or does a flat stomach depend more on diet and general exercise than a specific routine? A review of all the research conducted on sit-ups reports evidence that they do improve flexibility and muscle strength and that in dogs flexing the spine has been shown to help the delivery of nutrients to the discs which could prevent stiffness.
So far, so good. But to get the desired six-pack does take an awful lot of work. In a small randomised controlled trial in Illinois in 2011 one group did daily abdominal exercises while the lucky control group did none. After six weeks detailed measurements were taken and it was found that the sit-ups made no difference to waist size or the amount of fat around their stomachs.
Many sportspeople do sit-ups as part of a raft of exercises which aim to improve their core stability, but research from Thomas Nesser from Indiana State University suggests that improving your core stability doesn’t necessarily result in better athletic performance.
Whether or not they provide you with precisely the physique or fitness you desire, could sit-ups bring unintended consequences such as back pain? Stuart McGill, professor of spine biomechanics at the University of Waterloo in Canada has been studying sit-ups for years and is convinced that the traditional crunch does indeed cause us harm.
Research published in 2005 on soldiers stationed at the US military’s Fort Bragg attributed 56% of all the injuries sustained during the two-yearly Army Physical Fitness Test to sit-ups
He conducted dozens of studies in his spine biomechanics lab using the cadavers of pigs, repeatedly flexing their spines in a similar way as a person might when doing a sit-up, but for many, many hours at a time. When he examined the discs in the spine afterwards, he found that they had been squeezed to the point where they bulged. If the same thing happened in a human this would press on the nerves, causing back pain, and possibly even a herniated disc.
Pigs were chosen for this experiment because their spines are more similar to human spines than those of many other animals, but of course critics of these studies point out, that there are still many differences between people and pigs. Also these studies involved thousands of continuous cycles of bending. Even when training hard, people take breaks between sets of crunches.
Perhaps these results tell us what might happen at the extremes in the unlikely event that you were to do sit-ups for hour upon hour, but in real life it’s clearly not the case that most people damage their discs most of the time when doing sets of 15 sit-ups. However, injuries can happen. Research published in 2005 on soldiers stationed at the US military’s Fort Bragg attributed 56% of all the injuries sustained during the two-yearly Army Physical Fitness Test, to sit-ups.
Some people seem to be more prone to back problems caused by sit-ups than others. We might be fine doing 30 sit-ups a day for decades, but we might not and it’s hard to know which group we fall into. It could come down to our genes. According to one paper, it’s not wear-and-tear that causes most of the difficulties, but genetic factors, which account for three-quarters of the differences between the people who do get back problems and those who don’t.
But if you want to crunch those abs, is there a way of limiting the risk?
The Twin Spine study has been following pairs of twins in Finland, Canada and US since 1991. The researchers have found that genetics play a huge part in people’s susceptibility to the degeneration of the discs in their backs. Even when one twin had a job requiring heavy lifting, while the other had a sedentary job, the frequency of back problems was about the same.
So sit-ups might lead to back pain, but only in some people. It’s a good excuse not to do them. But if you want to crunch those abs, is there a way of limiting the risk? Professor Stuart McGill recommends sliding your hands under your lower back to stop it flattening against the floor. This minimises the stress on your back. Bend one knee up and keep the other extended. Then raise the head and shoulders off the ground by a very small amount. He says to imagine your head is resting on bathroom scales and you are just lifting your head enough for the scale to show zero. This exercise is described in much more detail in his book Back Mechanic.
In his review of the sit-up research Bret Contreras from Auckland University of Technology in New Zealand recommends limiting spinal exercises to 60 repetitions per session, beginning with only 15 and building up gradually. Finally, when we’ve been lying down overnight or even sitting down for a long time we gain a small amount of height, which makes sit-ups harder and increases the risk of injury. So don’t stand up from hours of sitting at your desk and immediately get down on the floor to do sit-ups and don’t bound out of bed and do them first thing in the morning.