How stretching actually changes your muscles - Malachy McHugh

翻译人员: Yip Yan Yeung 校对人员: Jacky He

Here we have an athlete preparing for a game.

这位运动员正在为比赛做准备。

They’ve put on their gear and done their warmup,

他/她披挂整齐，做完热身运动，

and now it’s time for one more routine— stretching.

是时候进行最后一项例行程序了， 那就是拉伸。

Typically, athletes stretch before physical activity to avoid injuries

运动员通常会在 运动前拉伸，避免受伤，

like muscle strains and tears.

如肌肉拉伤或撕裂。

But does stretching actually prevent these issues?

但拉伸真的可以避免这些问题吗？

And if so, how long do the benefits of stretching last?

如果真的可以， 拉伸的效果可以持续多久呢？

To answer these questions,

为了回答这些问题，

we need to know what's actually happening in the body when we stretch.

我们先得了解拉伸的时候， 身体里到底发生了些什么。

There are two kinds of stretching our athlete might be doing.

运动员可能会进行两种拉伸。

Dynamic stretches, which are controlled movements

动态拉伸，即加以控制的动作，

that engage a range of muscles throughout the motion.

其覆盖到多块肌肉。

And static stretches, where the stretcher holds a position

静态拉伸，即拉伸者保持某个动作，

to keep specific muscles at a fixed length and tension.

让某块特定的肌肉 保持一定长度和舒展程度。

Our athlete is currently doing a static hamstring stretch—

这位运动员正在进行 静态腘绳肌拉伸——

a 30 second interval where he pulls his hamstring

每隔 30 秒， 他会将腘绳肌拉伸到

beyond its usual range of motion.

其正常运动范围之外的位置。

However, while we often think of stretching a muscle

但是，虽然我们通常认为拉伸肌肉

like stretching a rubber band,

和拉扯橡皮筋差不多，

muscles are actually comprised of various tissue types,

但肌肉其实包含了多种细胞组织，

which interact to make a complex material.

这些组织互相作用， 使肌肉成为了一种复杂的材料。

Rubber is elastic, meaning it resists being stretched

橡胶有弹性，也就是说 它在被拉伸的时候会抵抗，

and then returns to its original shape.

再复原成原始的形状。

But muscle is viscoelastic.

但肌肉有粘弹性。

This means that, in addition to those elastic qualities,

意思是除了弹性的特质，

muscle changes under the stress of being stretched.

肌肉还会因拉伸造成的压力发生变化。

Let’s see this in action.

我们来看一个实例。

At the large scale, this hamstring stretch is pulling on layers of protective tissue

宏观来看，这种腘绳肌拉伸 会拉扯肌肉纤维周围的筋膜层，

surrounding the muscle fibers,

as well as the tendons that connect this muscle to nearby bones.

也会拉扯连接肌肉 与其附近骨骼的肌腱。

These tissues contain elastic proteins like collagen and elastin,

这些组织含有弹性蛋白， 如胶原蛋白和弹性蛋白，

which allow them to slightly elongate over the duration of the stretch.

使这些组织能够在拉伸期间 稍微拉长一些。

At the smaller scale, these skeletal muscle fibers are comprised

微观来看，这些骨骼肌纤维包含了

of millions of sarcomeres—

上亿段肌节——

the smallest contracting unit of muscle tissue.

肌肉组织中最小的收缩单元。

Sarcomere’s long, fibrous proteins can relax to elongate muscle fibers

肌节中的长纤维状蛋白 可以松弛以舒展肌肉纤维，

or they can contract to shorten them—

或收缩以拉紧肌肉纤维；

pulling on tendons and protective tissue

拉扯肌腱和筋膜，

to create the force propelling our athlete’s body.

便产生推动运动员身体的力量。

And when those tissues have been stretched out,

在这些组织被拉伸开以后，

they retain their strength at longer lengths,

它们就能将强度维持更长的时间，

allowing our athlete to take full advantage of his improved range of motion.

让运动员充分运用 提升后的动作幅度。

Unlike a rubber band, this muscle’s resistance to stretching decreases

与橡皮筋不同的是， 肌肉对拉伸的阻力每拉伸 30 秒

with each 30 second stretch,

都会减少，

allowing our athlete to continually elongate his hamstring.

让运动员得以持续伸长腘绳肌。

And this improved flexibility likely decreases the chance

提升后的柔韧性降低了

of incurring certain muscle injuries.

造成某些肌肉损伤的可能性。

But due to muscle’s elastic properties,

但由于肌肉的弹性，

this effect will be gone in just 10 minutes without further activity.

只要没有接着运动，这个效果 就会在仅仅 10 分钟后消失。

The exercise from his match should elevate his muscle’s temperature

赛场上的运动能提高他的肌肉温度，

and continue elongating the muscle,

在整场比赛中持续拉长肌肉，

maintaining his increased flexibility throughout the game.

维持他增强的柔韧性。

But once he gives his hamstrings a break,

但只要他一让腘绳肌休息一会儿，

they’ll retract back to their previous state.

它就会收缩回原始状态。

So if all this is just temporary,

如果这些都是暂时的效果，

how can you permanently improve your flexibility?

那你该如何永久地提升你的柔韧性呢？

For skeletal muscles, improved flexibility comes from additional sarcomeres,

就骨骼肌而言， 增强的柔韧性来自更多的肌节，

which allow you to maintain strength at even greater lengths.

甚至可以让你更久地维持力量。

Sarcomeres are added and subtracted to muscles

肌肉中肌节的增减

depending on how frequently they’re used,

取决于肌节的使用频率，

so improving overall flexibility requires a comprehensive stretching regimen.

因此如果要整体提升柔韧性， 就得有全面的拉伸计划。

Plus, you need to stretch often— very often.

你还得经常拉伸，时常地拉伸。

Current research suggests at least 10 minutes a day for roughly two months.

近期的研究建议每天至少要拉伸十分钟， 大约坚持两个月。

And since it's unsafe to hold any stretch for too long,

由于持续过久拉伸不太安全，

it's recommended that you break up your stretching within any given session.

建议将拉伸分段进行。

Frequent stretching also makes lasting changes to your brain.

频繁的拉伸也会对你的大脑 产生持久的影响。

The more you stretch a muscle, the higher your pain threshold becomes,

你越频繁地拉伸某块肌肉， 疼痛阈值就越高，

allowing you to stretch further and further.

让你可以更进一步拉伸。

Long-term improvements to your flexibility can provide

柔韧性的长期改善可以为你带来

a better range of motion for your joints,

更高的关节活动度，

potentially reducing your risk of muscle injury in the short and long-term.

从短期、长期来看都有可能 降低肌肉损伤的风险。

But it’s also possible to stretch too much,

但是拉伸过度也是有可能的，

as flexible people can move their joints in potentially dangerous ways.

柔韧性强的人可能会 以有危害的方式活动关节。

Stretching also isn't helpful for every kind of movement,

拉伸也不会有助于每一种运动，

especially those where muscle injuries aren't very common.

尤其是肌肉损伤不太频繁的运动。

For example, long distance running only involves a small range of motion

比如，长跑只需要 相关关节的小幅度活动，

for the joints involved,

so stretching is unlikely to prevent that sport’s most common injuries.

因此拉伸就不太可能 预防这种运动中最常见的损伤。

When it comes down to it,

归根结底，

different lifestyles require different kinds of mobility.

不同的生活方式 需要不同的活动量。

And no single stretching regimen is flexible enough to fit every situation.

没有一种拉伸的方式 适用于各种情况。