The Science of Ice Baths 冰浴里的科学

Whether or not you would personally plunge into an ice bath， cold-water therapy is having a moment.

不管你是否愿意亲自尝试冰浴，冷水疗法正风靡。

It sounds like a form of torture. If you wince at the idea of lowering yourself into a regular swimming pool， why voluntarily cover yourself in water around the temperature at which it turns to ice？ Well， having an ice bath is able to have the word ‘therapy’ affixed to the end of it because of the purported benefits for the body and perhaps even the soul.

冰浴听上去就有一种摧残人的感觉。如果一个人光是想到下进普通泳池就胆战心惊的话，怎么会心甘情愿地泡进温度低至冰点左右的水里呢？其实，“冰浴”后面可以加上“疗法” 一词，因为据说冰浴对身体甚至心灵都有益处。

“Like coffee on steroids1”

“像喝了功效加倍的咖啡”

Kyle Miller lives in Finland， close to Norvajärvi， a lake in the Lapland region2 in the north. Ice baths are a daily routine for him—and around 50% of Finnish people. Every day， he walks out of his house in the morning and reaches the lake within two minutes.

凯尔·米勒生活在芬兰，家住芬兰北部拉普兰地区诺瓦贾维湖附近。冰浴是他和大约半数芬兰人的日常惯例。每天清晨，米勒都会走出家门，用不了两分钟就可以到达湖边。

There， he lowers himself into a hole that he hacked out of the ice himself， where he stays for 20 calm breaths—approximately two minutes.

他自己在冰面上凿了一个洞，就从这个洞下水，在水中平静地呼吸20次——大约两分钟。

“It’s like coffee on steroids，” he says. “Everything in your system is like， ‘What’s going on？ OK， I’m awake; I’ve never felt so alive in my life; this is amazing; I want to get out of here.’”

“就像喝了功效加倍的咖啡。”他说，“身体各处的感觉就像，‘怎么回事？哈，我清醒了。我感受到了这辈子从未有过的活力。太神奇了。我要出去了’。”

Miller calls the practice “an immediate shock of adrenaline on your system”， for obvious reasons. He says， “After going through such a challenging ordeal， I’m ready to take on anything and everything in the world.”

米勒将这种体验称为“肾上腺素对人体的直接冲击”，而原因显而易见。他说：“在经历过如此具有挑战性的严酷考验之后，我随时可以迎接世上的一切挑战。”

So what are the concrete benefits？ Cold-water therapy， and its close cousin cold-water swimming， have demonstrated encouraging results in various studies as ways to improve wellbeing， both physical and mental.

那么，冷水疗法具体好在哪呢？冷水疗法以及与其相近的冷水游泳在各种研究中都显示出了可喜效果，可使身心双双受益。

Perhaps most famously， the method is prescribed as a way to mitigate muscle soreness. Like applying ice to a wound， says Miller， it is intended to act as a form of pain relief.

这种疗法最显著的益处也许就是可减轻肌肉酸痛。米勒说，就像在伤口上敷冰一样，这种疗法能起到缓解疼痛的作用。

Various studies in the last ten years have discovered that cold-water immersion can improve muscle pain to some extent. In 2018， cold-water immersion in rugby players was said to have provided “some beneficial effect by reducing fatigue and soreness”; in 2014， another study concluded that “cold-water immersion appears to facilitate restor- ation of muscle performance in a stretch-shortening cycle”.

过去十年的各种研究表明，泡冷水可以在一定程度上缓解肌肉疼痛。2018年有研究结果表明，泡冷水为橄榄球运动员“消除疲劳、减轻酸痛，产生了一定的有益影响”。2014年的一项研究总结称：“泡冷水似乎有助于肌肉在牵拉-收缩循环中的状态恢复。”

Inflammation is a malady treated well by cold temperatures， because blood vessels constrict， helping to bring down swelling.

低温疗法可以很好地治疗炎症，因为低温可以使血管收缩，从而有助于消除肿胀。

The benefits go on. A 2013 study demonstrated a link between cold acclimation—different to cold-water therapy but still all about reducing body temperature—and the production of brown adipose tissue activity， which helps us lose weight.

低温疗法的益处不止于此。2013年的一项研究表明，冷适应（不同于冷水疗法，但仍与降低体温有关）与棕色脂肪组织产生活性之间存在关联，而有活性的棕色脂肪组织有助于减肥。

Weight loss would be unsurprising given that the technique is also proven to increase metabolic rate： when you submerge your body in cold water， your heart rate tends to go up and your body works harder to efficiently pump blood around the circulatory system.

能产生减肥效果并不令人惊讶，因为低温疗法经证明还可以提高人体的代谢速率：浸入冷水中，心率通常会上升，身体会更努力地泵送血液，有效促进循环系统运转。

Patchy proof

有待进一步研究

It is also said that cold-water therapy improves your sleep. Anecdotally， that could well be true for many people， but there are studies that have found both positive and non-existent correl-ations. In fact， there are more studies demonstrating a link between good sleep and hot showers than good sleep and cold showers.

还有说法称，冷水疗法可以改善睡眠。据称，这对许多人来说很可能是真的，但有的研究发现两者正相关，有的则发现两者不相关。事实上，比起发现良好睡眠与冷水浴有关的研究，发现良好睡眠与热水浴有关的研究更多。

Many of the studies on cold-water immersion have used small sample sizes， and their results aren’t hugely conclusive one way or another. Because the practice is often combined with a few different elements—exercise and socialising， for example—it is difficult to pinpoint the role that the cold water plays.

许多有关冷水浴的研究采用的样本量较小，而且研究结果在某种程度上都存在相当大的不确定性。因为冷水浴往往多少掺杂着其他因素——比如锻炼和社交——因此很难确定冷水所起的作用。

Duncan Leighton， a physiotherapist who works for at-home spin and fitness brand Apex Rides， thinks the findings should be treated with a pinch of salt3 and that， though it has been around for hundreds of years， perhaps ice bath therapy is just in vogue at the moment.

邓肯·莱顿是一名理疗师，就职于专攻家用动感单车与健身的公司“顶点骑行”。他认为，应对相关研究的结果持怀疑态度，尽管冰浴疗法已经存在数百年，但也许只是目前风行一时。

One issue， Leighton says， is that there isn’t even conclusive scientific evidence on why we get muscle soreness. If we don’t exactly know why the problem occurs in the first place， it’s tough to assess treatments “because we kind of don’t know what we’re treating”. Indeed， a 2019 study found that ice baths seem to impair muscle conditioning after leg exercises.