如何及为何增强心脏和心血管健康

我们会在节目笔记里提供所有这些数据，还有直接指向相关表格的链接。

We'll cover all those data and have of course plenty of links directly to tables in the show notes.

但在那之前，我觉得我们得先好好聊聊，心肌到底有什么特别之处。

But I think before we do that, we actually need to talk more about what makes the cardiac tissue so special and unique.

在其他几期节目中，我会讲很多关于骨骼肌的内容。

I'm gonna talk a lot about skeletal muscle in other episodes.

所以这里我想专注讲讲心肌纤维的独特之处，这能帮我们更好地理解：为什么我们看待它的方式不同，该怎么做，以及除了VO2最大值之外，还有更多值得留意的地方。

And so what I wanna do here is really focus on what is unique and special about the muscle fibers in the heart as this is gonna explain a lot about how we interpret it, what we do about it, and how actually there's more things to pay attention to than just your VO2 max.

为了开启这个话题，我想先问你们一个问题。

To get us started here, I'd like to actually ask you a question.

你有没有想过，为什么你的心脏从来不会酸痛？

That is, you ever thought about why your heart never gets sore?

就像我开头说的，人体有三种肌肉，对吧？

I mean, as I said at the beginning, you've got three types of muscle, right?

平滑肌没有收缩功能，跟力量产生和人体运动都没什么关系。

Smooth muscle, which doesn't have contractile properties and it's not important or relevant to force production or human movement.

你还有骨骼肌，就是身体其他所有的肌肉。

You've got skeletal muscle, which is everything else.

比如手臂、腿、脖子、肩膀这些部位的肌肉。

It's your arms, legs, neck, shoulders, things like that.

还有心肌，也就是你的心脏。

And then cardiac muscle, your heart.

当你剧烈运动，或者尝试一些新动作、加大活动范围、多做离心训练这些事情时，肌肉都会酸痛。

And you know when you exercise really hard or do something unique and novel, train over a larger range of motion, do more eccentric work and all these other things, your muscles get sore.

但为什么你的心脏不会酸痛呢？

But why does your heart rate get sore?

如果你现在突然出去跑步，而且好几年没锻炼过，跑完VO2最大值测试，你肯定会累得不行，但第二天醒来，心脏并不会酸痛。

If you went out right now and you haven't exercised in years and you ran a VO2 max access, you would get extremely tired, but you would not wake up the next day with a sore heart.

你的肋间肌、肋骨、下背部这些地方可能会酸，但心脏不会。

Your intercostals or your ribs or your low back or something might be sore, but not your heart.

那这是为什么呢？

Well, why is that?

其实，这个问题的答案能帮我们更好地理解如何评估心血管系统的功能，以及为什么训练心脏的方式必须和训练骨骼肌完全不同。

Well, actually the answer to that tells us a lot about how we should assess the functionality of our cardiovascular system, as well as how we need to think about training it differently than we train skeletal muscle.

说到底，这始终离不开生理学原理，对吧？

You see, it always comes back to physiology, right?

所以我们接下来会一步步带你了解心脏的结构、肌纤维的排列方式，以及它为什么会有这样的收缩机制。

So there's a reason we're gonna walk you through how the heart is set up, the structure of the fibers, why it contracts the way it does.

因为这些知识能让我们明白，必须彻底转变对心脏训练和提升方式的认知，和之前讨论过的骨骼肌训练完全不同。

Because again, this gives us insights into why we need to totally change our mindset about how we're going to train and improve it relative to how we talked about and we'll talk about training our skeletal muscle.

心脏其实由四个独特的部分组成，我们称之为心腔。

So the heart is made up of really four unique areas and we call these chambers.

上面有两个叫心房，左右各一；下面有两个叫心室。

There's got two at the top called your atria, your left and right, and two at the bottom called your ventricles.

简单来说，血液先流入心房，心房收缩时把血挤进心室。

And really the idea is you take blood from the atria, you squeeze and contract the atria, that pushes blood into the ventricles.

接着心室收缩，把血液泵出心脏，输送到全身。

The ventricles then squeeze and that pushes blood out of your heart and into your system.

这里面还有很多细节，不过目前这样理解就够了。

There's a lot more detail in there but that's close enough for now.

最值得关注的是左心室。

Of primary interest is the left ventricle.

这也就是为什么你看到的心脏图，跟五岁女儿画的那种对称心形不一样。

That's actually the reason why when you see a heart, it isn't that perfect unique symmetrical shape that you envision when your five year old daughter draws it.

它其实稍微向左倾斜一点。

It's actually slightly tilted to the left a little bit.

这是因为左心室比右心室大得多——右心室只需要把血泵到肺部，而左心室得把血泵出心脏，送到全身，从脚趾尖到头顶，再流回心脏。

That's because the left ventricle itself is larger than the right ventricle, primarily because the right ventricle just needs to pump blood to the other side of the heart, but the left ventricle pumps it out of your heart in throughout the entire rest of your body, down to the tip of your toes and then all the way back up into your heart.

它必须有足够的力量，克服重力，顶着肌肉收缩的阻力，把血液送回心脏。

So it has to have enough force to have all of that blood movement up against gravity, fighting through muscular contractions to get blood all the way to return.

当然，身体也有一些机制能帮血液回流，但主要还是靠左心室完成这项任务。

Now you have some ways that you can help that blood return along the way, but primarily that's what the left ventricle has to be able to do.

正因为承担着更重的任务，换句话说，需要产生更大的力量，左心室才长得更大。

And so because it is asked to have a higher function, in other words produce more force, it actually is larger.

肌肉的大小和力量之间始终存在关联，不过这种关系不是线性的，我们会在其他期节目中详细讲。

There is an association at all times between muscle size and muscle strength, though that is not linear and we'll discuss that in other episodes.

所以整体来看，左心室更大一些。

And so globally the left ventricle is larger.

心脏还有一个独特之处，就是它肌纤维的构成方式。

What's also unique about the heart is that the way that the muscle fibers themselves are made up.

你看到的心脏，和其他肌肉一样，是由几百甚至上千根独立的肌纤维组成的。

And so you see your heart like any muscle is just a composite of many hundreds if not thousands of individual muscle fibers.

关于这些肌纤维的特性，我们会在骨骼肌的节目中再细说。

And we will talk again about the nature of those in the skeletal muscle episodes.

但现阶段，我们需要明白它们其实和普通肌肉很不一样。

But for now we need to think that they are actually quite different.

当你想到肌肉时，比如二头肌、腘绳肌或者股四头肌，它们都有特定的功能。

And so while you think of muscle, your biceps muscles or hamstrings muscles or quadriceps muscles, they are meant to have specific functionality.

在肌肉科学里，我们经常用一句话：结构决定功能。

A term that we're gonna use in muscle science all the time is structure equals function.

所以结构决定了功能。

So the structure, the way that it is built equals the functionality.

举个简单的例子，你的腘绳肌主要是用来做爆发性动作的，比如跑步、冲刺、跳跃这类活动。

So as a quick example, your hamstring muscles are primarily meant for explosive movements, to run, sprint, jump, stuff like that.

因此，它们的构造、收缩方式以及与骨骼的连接方式，和你的竖脊肌——也就是下背部肌肉——完全不同，后者的作用只是让你一整天保持直立。

And so the way that they are built, the way that they contract and oriented and attached to the bone are different than say your spinal erectors, your low back muscles that are meant to just keep you up and vertical all day.

它们并不需要频繁爆发或产生很大的力量。

They're not really meant to be exploded or contract with a lot of force.

它们只需要持续轻微收缩，帮你保持直立和良好的体态。

They wanna be on and contracted mildly to keep you vertical and direct with that nice great posture.

当我们转向心脏时，就得想想：心脏真正需要承担什么功能和负荷？

When we go to the cardiac side, then we start thinking, okay, what is the actual need and demand of the heart?

虽然我们希望骨骼肌能随时启动和放松，实现精准的运动控制，但这并不是心脏的职责。

And so while we want to be able to turn skeletal muscle on and off a lot and to have really specific and precise movement, that's not the role of the heart.

实际上，我们需要转向另一种完全不同的设计。

In fact, we need to hedge towards something else.

我们只需要心脏收缩就行。

We just want the heart to contract.

不需要它以不同的方式收缩。

We don't need it to contract in different ways.

不需要精细的控制。

We don't need high precision.

我们需要的是完全的收缩。

We need a full contraction.

而且更重要的是，我们必须避免收缩失败的可能性。

And in fact, importantly, we need to hedge against the possibility of not having a contraction.

如果你的腘绳肌没激活好，或者觉得臀肌没发力、力量不够，这并不会真正影响你的日常生活。

If your hamstrings don't fire appropriately, or you think your glutes are turned off or they're not as strong as you'd like, that's not gonna really change your ability to live.

如果心脏有一次没能收缩，那就是严重的问题了。

If your heart fails to contract even one time, you have serious problems.

如果连续几分钟都停止收缩，人就没了。

If it fails to do that for just a couple of minutes, you're dead.

所以对它的要求完全不同。

And so the demand is quite different.

它必须非常稳定，每次都要做同样的事，还得有备用机制。

It needs to be very consistent and it needs to basically do the same thing every time and it needs to have fail safes.

就算出了问题，它还是能正常收缩。

So some problem exists, it can still contract.

因此，心脏肌肉纤维的特性也大不一样。

And so the nature of the fibers in your heart are quite different.

普通肌肉纤维特别长。

In muscle, they are very, long.

比如你的股四头肌，单根纤维能长达十几厘米。

So you'll see them up to five to six inches in length of a single muscle fiber in say your quadriceps.

但心脏里的纤维又短又粗。

They are quite short and thick in the heart.

它们的横截面积差不多。

The diameter cross sectional area is roughly the same.

你所说的横截面积大约是四五千平方微米。

You're talking about something like four to 5,000 micrometers squared in terms of cross sectional area.

但长度却非常非常短。

But the length is very, very short.

现在你看到的长度大概只有零点一厘米左右。

Now you're talking about something like 0.1 centimeters in length.

我们之所以需要这样，或者说实际情况就是这样，是因为这些肌纤维本身是单核的。

And the reason we want that or the reason that actually is happening is because the fibers themselves are what are called single nucleated.

这和骨骼肌有显著不同，骨骼肌的一个细胞里有成千上万个细胞核。

And so this differs significantly from skeletal muscle that has thousands of nuclei in the cell.

简单提醒一下，细胞核是存放DNA的地方。

The nuclei as a quick reminder, are the place in which you hold your DNA.

它是细胞的控制中心。

It is the control center of the cell.

它决定细胞如何应对外界刺激、恢复、修复、合成蛋白质、增加或减少线粒体，等等。

It determines how the cell responds to external stimuli, recovers, repairs, goes through protein synthesis or adds more mitochondria, deletes them or whatever the case may be.

这些过程都是由细胞核控制的。

This is being run by the nuclei.

所以骨骼肌里有这么多细胞核，才让它能高度灵活、适应性强，对运动、干预、缺乏运动或其他变化都能迅速做出反应。

And so by having more of them in skeletal muscle, it allows it to be extremely plastic and adaptable and responsive to exercise or interventions or lack of exercise or anything else going on.

但我的心肌不需要这种能力。

I don't need that in cardiac tissue.

我不需要它快速生长、萎缩或死亡。

Like I don't need it to be growing and shrinking and dying really quickly.

我需要的是它在激活、收缩以及收缩时产生的力量上保持高度稳定。

What I need it to be doing is extremely consistent with both its activation, so it's contraction, and the force applied in that contraction.

因此，心肌细胞只有一个细胞核，这说明它的主要功能根本不是适应性变化。

So the fact you've got a single nuclei in the cardiac tissue tells you its primary role is not actually adaptation.

事实上，根据不同的研究，你可能会发现，你一生中心脏肌肉纤维的更新率大约在50%到70%之间。

In fact, depending on the study you look at, you're gonna see that the muscle fibers in your heart are gonna turn over somewhere between 50 to maybe up to 70% throughout your lifetime.

也就是说，你小时候拥有的很多心肌纤维，尤其是青春期以后的，会一直陪伴你到生命结束。

Meaning many of the fibers in your heart that you have as a child, especially past puberty, are gonna be there the rest of your life.

细胞更新的量并不大。

There isn't a huge turnover.

但如果你看看皮肤，情况就完全不同了。

Now that differs considerably if you look at something like the skin.

皮肤的更新速度应该很快。

That's probably going to turn over.

大概每三十到五十天，你的皮肤细胞就会全部换一遍。

You will have all new skin cells every thirty to fifty days or something like that.

红细胞的话，大约每一百二十天更新一次。

Red blood cells, maybe more like every one hundred and twenty days.

而骨骼肌的寿命可能长达十年左右，甚至更久。

And skeletal muscle can actually have a lifespan of maybe a decade or something like that, maybe a little bit longer.

但你的心脏组织几乎不会更新。

But your heart tissue is gonna very rarely turn over.

它本来就不是用来快速增殖的。

It's not meant to be hyperplastic.

这并不意味着它不会对高血压、运动这类刺激做出反应、适应和改变。

That does not mean it doesn't respond and adapt and change to stimuli like high blood pressure, like exercise.

它确实会的。

It absolutely does.

只是发生得慢得多。

But it happens much slower.

但这不是它的主要功能。

That's not the primary job.

所以心肌纤维本身更短、更粗壮，每个细胞只有一个细胞核，但它们还具备一些骨骼肌没有的独特优势。

So the fibers themselves are shorter, they are nice and thick and they have a single nuclei, but they have a couple of actual special unique advantages that skeletal muscle does not have.

比如，它们通过一种叫闰盘的结构相互连接。

For example, they are connected to each other through what are called intercalated discs.

这种结构是心肌组织特有的。

Now these are specific and unique to cardiac tissue.

而真正起作用的是其中的缝隙连接。

And what actually allows to happen is for there to be what's called gap junctions.

所以纤维之间几乎有小小的通道相连。

So there's almost little entry points from one of the fibers to the next one.

这样一来，动作电位——也就是引发纤维收缩的电信号——就能在纤维间传递。

And what that does is it gives the ability for an action potential, which is the electrical voltage that goes into the fiber that causes it to contract.

这种设计让电压可以从一根纤维传到下一根。

It allows that voltage to leak from one fiber to the next.

骨骼肌可不能这样，不然你收缩某根或某组纤维时，可能会不小心连带激活其他纤维。

You wouldn't want this in your skeletal muscle because that means when you contract one fiber or set of fibers, you might accidentally contract other ones.

这可不行。

Not good.

别忘了，骨骼肌需要的是高度精准的运动控制。

Remember, we want high precision and control of movement in skeletal muscle.

而心肌呢，我们只希望它整体同步工作。

With cardiac tissue we just want it all to go.

所以，正是通过这些闰盘和缝隙连接形成的开放通道，哪怕某个细胞的电信号启动困难，只要有一个细胞被激活，信号就能扩散到所有其他细胞。

And so the fact that we have these open gates through these intercalated discs and through these gap junctions that says, hey, if for some reason we struggle to get intervention or activation of an action potential, as long as we get it into one of the cells, it'll be able to leak into the rest of them as well.

所以在这种情况下，我们更看重确保收缩，而不是精确控制。

So in this case, we wanna hedge guaranteed contraction over control.

再举个类似的例子，骨骼肌是由所谓的运动单位组成的。

Now, a similar point, if you go to skeletal muscle, it exists in what are called motor units.

一个神经元可能支配几百甚至上千条肌纤维，这就是运动单位的意思。

So you might have several 100 to even many thousands of muscle fibers all innervated or controlled by one basic nerve is the way to think about that.

通过开启或关闭更多的运动单位，我们可以调节同时收缩的肌纤维数量。

This allows you again to upregulate how many of your muscle fibers in your muscle are contracting at a given time by turning on or off more total motor units.

心脏里没有这种结构。

The heart doesn't have any.

心脏里不存在运动单位。

There's no motor unit in the heart.

我们不能接受神经出问题、被阻断或死亡后，那些肌纤维就无法收缩的后果。

We don't want to have the consequences of what if a nerve fails or is blocked or dies and now we can't contract those fibers.

所以实际上，心脏的收缩并不依赖神经系统的激活。

And so in fact, the heart is not dependent upon nervous system activation to contract.

我再重复一遍。

Now I'll say that again.

心脏收缩并不需要任何神经系统的激活。

The heart does not require any nervous system activation to contract.

这正好解释了为什么在电影《夺宝奇兵3：魔宫传奇》里，那个角色能把手伸进别人胸口，直接把心脏掏出来。

And this explains exactly why you can do really awesome and interesting things like in the movie Indiana Jones, Temple of Doom, where the gentleman reaches into the guy's heart and he pulls it directly out of it.

他盯着手里那颗心脏，它居然还在继续跳动。

And he stares at that man's heart that's in his hand and it still continues to beat.

这是因为，与需要神经激活的骨骼肌不同，心肌不需要神经信号就能工作。

This happens because again, unlike skeletal muscle which requires nervous system activation, the cardiac tissue does not.

它有自己的精密节律，能够独立产生收缩所需的电信号，完全不依赖神经系统。

It has its own intricate rate and can spontaneously produce the electricity needed to contract independent of the nervous system.

但这并不意味着神经系统对心脏没有作用。

Now that does not mean the nervous system does not have a role in your heart.

它确实有作用。

It absolutely does.

我们会详细讨论这一点。

And we're gonna talk a lot about that.

事实上，理解这一点对监测整体疲劳、恢复状态、表现以及自主神经系统的活跃程度至关重要。

In fact, it's incredibly important to understand that as a way to monitor global fatigue, readiness, performance and overall nervous system activation.

骨骼肌和心肌的另一个区别在于它们收缩的方式和持续时间。

Another thing that differentiates the skeletal from the cardiac tissue is how and how long they contract.

在骨骼肌中，我们实际上需要实现一种叫作‘总和’的现象，以达到强直收缩。

In skeletal muscle, we actually want the ability to do what's called summation to reach tetany.

比如你的肱二头肌，肌纤维会在电信号刺激下收缩。

And so what happens is the muscle fibers in say your biceps brachii will contract with that electrical potential.

还没等它完全回到静息状态，就会再次收缩。

And then actually almost before it gets all the way back to baseline, it will contract again.

然后又一次，又一次地收缩。

And then it'll contract again and contract again.

这些微小的收缩会叠加起来，形成总和效应。

And so those those mini contractions start to stack on top of each other or summate.

如果你持续这么下去，最终会达到完全强直的状态。

And in fact, if you do that long enough, you can reach what is called full tetany.

你可以把这想象成肌肉抽筋。

Think of this as a muscle cramp.

这时候，肌纤维会持续收缩，而不是一紧一松地反复活动。

So this is the muscle fibers themselves contracting permanently instead of doing this kind of on off on off rhythm.

心肌不会这样。

Cardiac tissue doesn't do that.

我想你大概能明白为什么。

And I think you could probably imagine why.

要是你的心脏发生强直，那可就糟了。

It would be a very bad thing for you to reach tetany of your heart.

还记得我们刚开始讲心脏结构时说的吗？心脏的主要功能，就是把血液从心房送到心室，再泵到全身。

Remember, when we first started talking about the anatomy of your heart, the primary job of the heart is to move blood from the atria or the top of the heart to the ventricles in the bottom and then move that out to the body.

如果心脏真的强直了，血液就无法流动，血液循环会完全停止，后果就是死亡。

So if this thing were to reach tetany, blood wouldn't move anywhere, you wouldn't be able to circulate any blood throughout your body and of course you would die.

所以小腿抽筋虽然疼、虽然烦人，但要是心脏抽筋那就严重多了。

So while it's okay to have a cramp in your calf and it's painful and it's annoying and it's all those things, having a cramp in your heart would be far worse.

所以身体会采取一些措施来预防这种情况。

And so your body hedges against that.

具体来说，骨骼肌有个叫不应期的特性，能让肌肉纤维在短时间内连续收缩。

And what it says is, all right, if I have this extremely fast, what's called refractory time in skeletal muscle, it's the ability to kind of contract multiple times within a single muscle fiber.

而心脏组织会延长收缩时间，避免这种重复收缩叠加在一起。

I wanna extend the time of contraction in the cardiac tissue so that I don't have that repeat in summation.

所以除了不能发生强直收缩，你还得给血液留出时间让心室充盈。

So in addition to not wanting tetany, you also need to allow time for blood to fill up the ventricles.

记住这一点。

Remember this.

我们稍后在讨论最大摄氧量的决定因素、如何改善其他各项指标，以及这些与静息心率、最大心率的关系时会再回到这个话题。比如为什么最大心率无法通过训练提高，为什么体能极好的人和体能较差的人最大心率没有差别，诸如此类的内容。

We're gonna come back to this later in the episode when we talk about determinants of VO2 max, what to improve in some of these other numbers, and why that relates to your resting heart rate, your maximum heart rate, why that's not trainable, why there's no difference in maximum heart rate between highly fit people and unfit people, and things like that.

因此，心脏重新充盈血液的能力至关重要。

So the ability of your heart to fill back up with blood is critical.

所以心脏必须收缩，留出足够时间让血液回流到心房或心室，然后再收缩一次。

So it's got to contract, allow enough time for blood to fill back into the atria or ventricle and then contract again.

心脏的收缩要平稳持久，组织本身不需要太多弹性。

So big long smooth contractions, not a lot of plasticity in the tissue itself.

我们得避免让心脏具备太精细的控制能力。

We want to hedge against having lots of fine motor control.

这里我们要的是稳定，而不是精准。

We want consistency over specificity here.

接下来，我们可以再回到我刚才说的那一点。

So another way to build on top of that is going back to what I said a second ago.

心脏是怎么在没有神经系统指挥的情况下产生收缩的？

How does it produce a contraction independent of the nervous system?

我之前举过《夺宝奇兵》里的例子，可能有点粗糙。

I gave you the potentially a little bit crude example from the Indiana Jones movie.

换个角度想，人要是昏迷了，心脏怎么还能继续跳动呢？

But another way to think about this is how can my heart beat if I'm unconscious?

如果我把大脑完全关掉的话。

If I've got the brain turned offline.

心脏还是会继续跳，因为它本身就有自己的节律。

Well it will continue to do that because it has this intrinsic rate.

你的心脏里有四个被称为起搏点的结构。

You've got four what are called pacemakers in your heart.

我最想重点讲的是窦房结。

The one I wanna cover and talk about the most is the SA node.

窦房结位于右心房，主要负责控制你的心率。

So the sinoatrial node, this is in the right atria and it controls for the most part your heart rate.

另外还有房室结、浦肯野纤维、希氏束之类的其他起搏点。

Now you've got other ones like the AV node, Purkinje fibers and bundles of his and things like that.

但那些都只是备用的机制。

But those are really backup systems.

一旦窦房结出问题，心脏就会自动切换到下一个，再下一个，依次往下走。

So in case the SA node fails, it'll go to the next one, go to the next one and all the way down there.

所以我们有多重安全机制，确保万一出问题，心脏依然能收缩——别忘了，只要有一小块组织放电，电信号就能通过缝隙连接传遍全心，让整个心脏有节奏地收缩。

So we've got various fail safes that give us the ability to say, alright, if we have a problem, we're still gonna get contraction because remember, all we've gotta do is get one chunk to fire and it'll spread through those gap junctions and get everything else to contract in the appropriate fashion.

所以我们需要这种主导机制。

And so we wanna have that imposition.

这也是为什么，如果你遭遇心肌梗死，心脏部分组织坏死，你依然能活下来——因为其他健康组织还能继续收缩，只是过程会变得复杂，对吧？

This is also why if you have something like a heart attack and several of your tissue in your heart die, you can still survive because you can get contraction of everything else but it complicates the process, right?

因为坏死的组织会中断电信号的传导。

Because we start to lose electrical impulse through the parts of the tissue that are dead.

而窦房结本身其实是个了不起的奇迹。

Now the SA node itself is actually a bit of a marvel.

你可能在学校听过这种说法：我们根本不知道它是怎么运作的。

You could sort of think about this and actually remember in school being told that we have no idea.

这至今仍是医学界的一大谜题：窦房结究竟是如何自发形成节律的。

It's one of the modern mysteries of the world of how the SA note intrinsically develops its pace.

不过，这种说法并不完全准确。

Well, that's not exactly true.

我觉得我老师可能也不知道答案，或者只是想鼓励我一下。

I think my teacher, they didn't know the answer or was just trying to hype me up a little bit.

我们现在对控制它的机制了解得更多了。

We know a lot more about what controls it.

事实上，影响它的因素有不少。

In fact, there's a number of things that go into that.

它确实还带点神秘感，我不想把这层神秘感抹掉。

It does have a little bit of wonder, I don't wanna steal that.

我们还不完全清楚它为什么以这种方式跳动，为什么几乎每个人的节律都这么相似，又怎么能自发地产生这些动作电位。

We don't know exactly how or why this thing beats the way it does, why it's similar between almost every human and how it can just spontaneously create these action potentials.

它的节律受多种因素调控，比如体内循环的内分泌或旁分泌激素、血压、收缩力、回流到心脏的血量（也就是前负荷），以及其他一些因素。

That is regulated by a number of things including various endocrine or paracrine, these hormones that are circulating in your system, blood pressure, the strength of your contraction, the amount of blood that comes back into your heart called preload and various other factors.

所以，真正影响它的其实是一个相当复杂的环境。

So it's actually a fairly complicated milieu that go into it.

我其实还是愿意让你把它看作一个现代之谜——它能凭空产生收缩和电刺激动作电位，仿佛带着某种魔力。

I'm actually still okay with you thinking about it as this modern mystery that has just this magical property where it contracts and causes electrostimulation action potentials out of nothing.

我也觉得这样没问题。

I'm cool with that too.

不过我们更清楚的是，它如何调控身体的其他部分。

What we do know more about though is how this regulates the rest of your body.

说到骨骼肌，我们知道具体需要一种叫乙酰胆碱的神经递质来激活肌肉。

So when we talk about skeletal muscle, we know specifically there's a neurotransmitter called acetylcholine that is required for muscle activation.

事实上，你的神经并不是直接连在骨骼肌上的。

So the reality of it is your nerves are actually not directly attached to skeletal muscle.

它们之间有一小段空隙。

There's a little space in between them.

乙酰胆碱存在于突触前的神经末梢上。

What happens is acetylcholine is on the presynaptic nerve.

就是这条伸过来的神经。

So this is the nerve that comes in there.

它会被释放到那片空隙里，然后结合到肌肉细胞表面的受体上。

It gets released into this little space in between, actually attaches to little ligand gates on the muscle itself.

它们会打开，让钠离子进入组织，引发一连串电生理反应。

They open up, they let sodium into the tissue and they cause a whole series of electrical things.

我们把这个过程叫做电信号→化学信号→电信号的转换。

We call this an electrical to a chemical back to an electrical signal.

所以，神经传递的电信号会变成化学信号，再变回电信号，从而触发肌肉收缩。

That's why you transfer an electrical signal down your nerves into a chemical signal back into an electrical signal that allows muscle contraction.

因此，乙酰胆碱是激发和激活骨骼肌的主要神经递质。

So once again, acetylcholine is the primary neurotransmitter that excites or activates skeletal muscle.

但令人惊讶的是，如果你把乙酰胆碱直接作用于心脏，它反而会让心跳变慢。

But shocking enough, if you put acetylcholine onto the heart, it slows it down.

没错，效果完全相反。

Yeah, it does the exact opposite.

所以体内有好几条神经参与其中，最著名的就是迷走神经。

And so you have a number of nerves that are coming in, probably the most famous is the vagus nerve.

注意，是 V-A-G-U-S，不是像那个城市名字那样念成 V-A-G-A-S。

Now this is a V A G U S, not a V A G A S like the city.

迷走神经和其他几条神经被称为副交感神经系统的驱动者。

So the vagus nerve and several others are what are known as parasympathetic drivers.

自主神经系统主要分为两大分支。

And so the autonomic nervous system is split up into two large branches.

第一个是副交感神经系统。

The first one is the parasympathetic.

这就是休息和消化的状态。

This is rest and digest.

它让你放松、犯困、情绪低落、平静下来，就是这些感觉。

This is relaxed, sleepy, depressed, chilled, all those things over there.

另一面是交感神经系统，实际情况比这复杂，但我们现在只需要了解这些。

The other side of the equation, and it is more complicated than this, but this is all we need to know for right now.

那另一个是交感神经系统吗？

Is this sympathetic?

这就是战斗或逃跑反应。

This is fight or flight.

这是冻结反应。

This is freeze.

这是激活状态，比如焦虑、警觉、兴奋，还有类似的各种反应。

This is action, anxiety, aware, aroused, and all kinds of things like that.

这两种状态我们都需要。

We want both of these.

它们对日常生活至关重要。

They are critically important for everyday life.

我们要想表现优异，就得靠它们。

We need these for high performance.

我们要想保持健康，也离不开它们。

We need these for health.

甚至只是活着，也得依靠它们。

We need these to just be alive.

所以我们需要能够适时地在这两种状态之间灵活切换。

And so we wanna be able to fluctuate back and forth between these two states appropriately.

它们不是简单的开关。

They are not on off switch.

更像是一种渐变或者切换。

They are more like a gradient or a toggle.

更像是调光开关，而不是非开即关那种。

They're a dimmer switch more so than they are, you know, again flipped on or flipped off.

所以，窦房结自身的跳动频率通常比你的静息心率要高。

So what happens is the intrinsic rate of that SA node is probably higher than your resting heart rate.

事实上，它可能希望每分钟跳动100到120次。

In fact, it probably wants to beat more like a 100 to a 120 beats per minute.

大多数人静息时的心率大概在每分钟60到80次之间。

Most people's resting heart rate is more like 60 to 80 beats per minute.

因此，你的迷走神经会持续释放乙酰胆碱，慢慢把心率降下来。

So you kind of have this vagus nerve that is constantly applying this drip of acetylcholine to naturally slow your heart rate down.

这其实是个很巧妙的机制，因为它意味着，如果你想加快心率，第一步并不一定是激活交感神经。

Now this is actually a really cool mechanism because what allows you to do is if you want to increase your heart rate, the very first thing you have to do is not necessarily turn on sympathetic drive.

其实只是降低副交感神经的活动。

It's just to reduce parasympathetic drive.

换个说法，想象你在下坡开车。

Another way to say that is imagine you're driving downhill.

比如你在旧金山，或者某个到处都是坡道的地方。

Say you're in San Francisco or someplace that has a ton of hills.

你正以每小时60英里的速度行驶。

And you're going at 60 miles per hour.

然后你决定想开得更快一点。

And you decide you wanna go faster.

这时候，你第一反应可能是踩油门。

Well, the initial instinct is to maybe hit the accelerator or hit the gas.

可以把这个比作交感神经的激活。

Think of that as the sympathetic nervous system.

但其实你根本没必要这么做。

But you don't actually have to do that.

第一步是确保你的脚没有踩在刹车上——也就是副交感神经系统。

The first step is just to make sure your foot isn't on the brake, the parasympathetic nervous system.

实际上，当你开车时，迷走神经一直在轻轻踩着一点刹车，让你保持放松的状态。

So kind of what's happening is at all times when you're driving, the vagus nerve is slowly keeping its foot just a little bit on that brake to keep you relaxed.

现在它又在这么做，这样如果你需要快速加速，我们根本不需要额外释放肾上腺素或去甲肾上腺素，只要停止让你减速就够了。

Now it's doing that again so that if you wanna go faster really quickly, all we have to do rather than giving out additional resources like epinephrine or adrenaline, all I actually have to do is stop us from slowing you down.

这其实是个典型的双重否定，对吧？

It's kind of one of those classic double negatives, right?

所以，只要抑制那个抑制者，你就能真正加速。

So if I inhibit the inhibitor, I can actually go faster.

只要我把脚从刹车上移开，心率自然就会升到每分钟100到120次左右，不用做任何其他事。

So if I remove my foot from that break, my heart rate will increase to again somewhere in that 100 to 120 beats per minute range, plus or minus here, without us doing anything.

如果我想继续加速，比如现在我正下坡，之前车速是60英里，我松开了刹车，现在车速到了80甚至100英里，但还不够快。

If I wanna continue to accelerate past that, so now I'm going down that hill, I was going 60 miles an hour, I've removed my foot from the brake, now I'm going 80 miles an hour or 100 miles an hour, but that's not fast enough.

我想飙到150英里，这时候就可以踩油门了。

I wanna go 150, now I can hit the accelerator.

现在我可以激活交感神经系统，增加肾上腺素，让心跳更快、泵血更强，从而产生更多能量，完成我想要的目标。

Now I can push down on the sympathetic nervous system, increase adrenaline, turn on faster rate and pump my heart even more to produce more work, more energy or whatever I'm trying to accomplish.

很好。

Great.

既然明白了这一点，我们回头来回答刚才的问题。

Now we've got that down, let's go back and answer our question.

为什么心脏不会酸痛？

Why doesn't the heart get sore?

我们来想一想。

Well, let's think about it.

是什么原因让骨骼肌感到酸痛？

What are the reasons that cause skeletal muscle to get sore?

记住，所有骨骼肌，除了一个，你猜得到是哪一个吗？

Remember, all skeletal muscle with the exception of one, and I wonder if you know which one that is by the way.

除了那一个例外，所有骨骼肌都是通过肌腱连接在骨头上的。

All skeletal muscle with the exception of one is connected to bone via tendons.

当我们肌肉收缩时，会牵拉结缔组织，进而拉动骨骼，让我们动起来。

And so when we contract muscle, pulls on the connective tissue, pulls on the bone to get you moving.

但我们的心血管系统、心脏并不是这样的。

Our cardiovascular, our heart is not that.

它并没有连接到任何骨头。

It is not connected to bone.

这根本不是它的功能。

It's not the point.

我们并不是要靠它来产生运动。

We're not trying to cause movement.

它其实只是和自己相连的。

It is really just connected to itself.

正因如此，我们没法要求它做超出原有范围的伸展。

So because of that, we can't ask it to go over any additional range of motion.

所以这一条因素就可以排除了。

So that factor gets thrown out.

我们唯一能做的，就是让更多的血液回流到心脏，让心脏处于离心拉伸的状态。

The only thing we can possibly do is put more blood back into the heart which puts it on an eccentric stretch.

这也就是我们目前唯一的途径。

That's our only mode here.

离心训练如果强度太大，或者突然以新的方式来做，确实容易导致肌肉酸痛。

Now eccentric exercise does lead to excessive soreness if done especially heavy or in a novel fashion with traditional exercise.

所以离心训练值得留意，但事实是，我们没法让心脏承受比体内现有血量更多的负荷。

And so eccentric exercise is something to pay attention to, but the fact is we don't have the ability to overload the heart more than the maximum amount of blood we already have in our system.

它早就适应了目前的所有状态，我们根本加不了什么新花样。

So there's no novelty we can add to it that it's not already used to.

顺便说一下，回答你刚才的问题：人体中唯一不直接连在骨头上的肌肉是什么？

By the way, to answer your question, what's the only muscle not directly attached to bone?

我给你个提示，你现在就能看到它在我身上。

I'll give you a hint, can see it on me right now.

如果你是我五岁的孩子，你肯定天天都想给我展示它。

And if you were my five year old, you would love to show it to me all the time.

是你的舌头。

It's your tongue.

挺有意思的，对吧？

Pretty cool.

没错吧？

Right?

好了。

All right.

我们继续说正事。

Going back to business here.

这跟关节活动度没关系。

So it's not range of motion.

也不是离心训练的问题。

It's not the eccentric training.

导致肌肉酸痛的其他原因，是强度更高。

Other things that cause soreness are higher intensity.

这里不太适用。

Not really applicable here.

再说一遍，如果你平时习惯在最大心率下收缩，那我们也没法突破那个极限。

Again, if you're used to contracting at a maximum heart rate, we're not gonna be able to go past that.

增加训练量。

More volume.

嗯，我们当然可以这么做，但增加训练量通常意味着在更广的活动范围内做更多动作。

Well, we could do that, but more volume tends to mean more exercise over more range of motion.

你的心脏一整天都在跳动。

Your heart beats all day.

它的跳动量并不会大幅波动。

It is not subject to that much change in volume.

如果你算算一天中心脏总共跳了多少次，就会发现，一点运动并不会让这个总量发生太大变化。

If you looked at the total amount of heart beats that you go through throughout the day, a little bit of exercise is not changing that volume too much.

所以，相对于这个基础水平，想大幅增加训练量其实很难。

So it's really difficult to add much volume relative to the standard or baseline there.

所以当你继续分析所有影响肌肉酸痛的因素时，会发现这些因素其实并不适用于心脏，因为这根本不是它主要的功能。

And so as you just continue to go down all the other factors that influence muscle soreness and you see they don't really apply to muscle, again, that's not its primary role.

虽然你在运动时可能会感到疲劳，尤其是耐力型运动，但心脏本身其实并不容易疲劳。

And so while you may get fatigued from exercise, especially endurance based exercise, the heart itself is not really subject to fatigue.

事实上，心脏很少会感到累。

In fact, the heart rarely gets tired.

它所含的线粒体数量远超骨骼肌。

It has far more mitochondria in it than skeletal muscle.

我们过去常把它称为终极的慢肌纤维。

We used to refer to this as the ultimate slow twitch muscle.

它并不是为了产生强大的收缩力而设计的。

It is not meant for force of contraction.

回到运动单位来看，我们其实无法直接改变心脏肌纤维的收缩力量。

Going back to motor units, we actually can't alter force of contraction in the muscle fibers themselves in the heart.

我们只能通过改变组织的拉伸程度来实现这一点。

We can only do it by changing the stretch on the tissue.

骨骼肌也是同样的道理。

Same thing in your skeletal muscle.

但这种情况下，你有两种选择，对吧？

But in that case you've got both options, right?

要么改变拉伸程度，要么改变收缩特性。

Change stretch or strain contractile properties.

心脏的收缩特性其实很难改变，尤其是短期内。

We really can't change the contractile properties in the heart, especially acutely.

我们能做的，就是让它承受更大的拉伸。

What we can do is put it on more stretch.

这意味着更多的血液回流到系统里。

This means more blood back into the system.

这叫前负荷，我们后面再详细讲。

Again, preload, we'll talk about that a little bit later.

后负荷是另一种方式。

Afterload is another way.

但如果我们让更多的血液回流，心肌就被拉得更长，这样它就能更好地做出反应。

But if we put more back into it, we put the muscle on a bigger stretch and this allows it to then respond.

我想到的是橡皮筋。

I'm thinking about like a rubber band.

如果我轻轻拉它，它就会弹回来。

If I pull it a little bit, it snaps back.

如果我拉得更用力，它弹回来的力就更大。

If I pull it a lot, it snaps back harder.

我们能做的其实就这些。

That's all we can really do.

但这并不是用来调节力量强弱的。

But it is not meant to be regulating force up and down.

我们根本就没有运动单位。

We don't even have motor units.

理想情况下，它就是全有或全无的。

It's an all or none thing, ideally.

所以那里头有大量的线粒体。

And so we've got a lot of mitochondria in there.

我们在有氧代谢方面非常出色。

We are phenomenal at aerobic metabolism.

再说一遍，我们谈的是肌肉收缩特性，不是你整个身体或心脏的有氧代谢。

Again, specifically within the contractile properties, we're not talking about aerobic metabolism of your entire system or heart.

我们说的是包围着心脏的毛细血管，是血液如何进入心肌组织，而不是心脏腔室里那些输送到全身的血。

We're talking about the capillary surrounding the heart itself, the ability to get blood into the tissue of the heart, not the blood actually in the chambers that you're using to send the rest of your body.

记住，你的心脏有自己的供血系统，不是它往外输送给其他器官的那些血。

Remember, your heart has its own blood supply, not the stuff it's trying to give out to everybody else.

想象一下万圣节，你坐在家里，面前放着一大桶糖果，这些是你要分给外面孩子的。

Think of this as Halloween where you're sitting in a house and you've got this giant bucket of candy and the candy you're giving out to the rest of the world.

你并不会吃这些分出去的糖果。

You're not eating that candy as well.

你另有储备，比如口袋里、家里还藏着一堆糖果，你就是从那儿拿的。

You've got another supply of candy in your back pocket and in your house and you're pulling out of that candy, if you will.

好的。

Okay.

心脏本身设计得非常耐疲劳、耐损伤、不易酸痛，也不会轻易改变其固有的收缩或正性肌力特性——心血管领域的专家会这么叫。

So the heart itself is meant to be incredibly robust against fatigue, against damage, against soreness, and against changing any of its inherent contractile or ionotropic is what the cardiovascular folks would probably call it, properties.

不过，心脏对运动的适应方式，和骨骼肌还是有些相似的。

That said, it does respond somewhat similar to skeletal muscle with exercise adaptation.

就像骨骼肌可以通过训练提升收缩力、速度和爆发力，也能增加肌肉体积，心脏也是一样。

So just like in skeletal muscle where you can add quality, contraction force and speed and power, and you can add quantity, muscle size, the same thing actually happens in the heart.

心脏确实能变得更强壮。

The heart can get physically stronger.

这样你每次心跳就能泵出更多的血液。

This would result in you pumping out more blood per pump.

心肌纤维本身的内在特性可能不会变，但心脏的收缩力量确实能增强。

Again, the fibers themselves won't necessarily change their inert properties, but the hard can contract with more force.

这个我们稍后再详细讲。

We'll talk about that a little bit later.

这被称为射血分数和每搏输出量。

That's gonna be referred to as ejection fraction and stroke volume.

它也可能变得更大。

It can also get larger.

通常在运动或健康生活方式改变后，你的心脏增大主要发生在左心室。

And in this particular case, typically what you'll see in response to exercise or healthy lifestyle behavioral changes, the enlargement in your heart you'll see will be primarily in the left ventricle.

因为左心室需要承受主动脉的压力，把血液泵到全身。

Again, is the one that's gonna have to deal with the pressure of the aorta, getting that blood out the rest of your body.

理想情况下，这个腔室的容积——也就是能容纳血液的空间——要么保持不变，要么稍微增大。

And what will ideally happen is the amount or size of that chamber, so the inside, the amount, the space that can be filled by blood will either stay the same or even get slightly bigger.

但你实际上是在心室外壁增加了一层组织。

But what you'll basically do is you'll pack on tissue to the outside of the ventricle.

这样心室变大了，能产生更强的收缩力，同时不会缩小腔室的容积。

So it gets bigger, allows it to produce more force, but it doesn't compromise the size of the chamber.

所以，你可以把左心室想象成一个气球。

So again, think about the left ventricle as a balloon.

如果这个气球变小了，里面能感觉到的血液也少了，那就出问题了。

If that balloon gets smaller and you can feel less blood in it, that's gonna be a problem.

我们也不希望它变得特别大。

We don't want it to necessarily be extremely large either.

如果心室壁增厚了，但气球的容积没变，那就能产生更强的收缩力，同时不影响总的血流量。

And so if the back end grows, but the chamber size, the balloon size stays the same, then we're gonna be able to contract with more force and not compromise our total blood flow.

如果你的身体实现了这样的适应，每次收缩能泵出更多血液，这个数值就叫每搏输出量。

If you achieved an adaptation like that and it allowed you to pump out more blood per pump, that number is called stroke volume.

也就是每次心跳或每次收缩时泵出的血液量。

So the volume of blood that comes out per stroke or per contraction.

从心室里完全排空的血液所占的百分比，就是射血分数。

The percentage of the blood that gets emptied out of that ventricle is called your ejection fraction.

假设你左心室里有100毫升血液，收缩后还剩50毫升在里面，那你的射血分数就是50%。

So let's just say there was 100 milliliters of blood in your left ventricle and you contracted and fifty percent fifty milliliters was left in the ventricle, your ejection fraction would be 50.

所以我们希望射血分数越高越好，这样才不会白费力气收缩，却让血液还留在心室里。

And so we would like to see high ejection fractions so that we're not wasting our time contracting and blood still sitting in the ventricle.

如果你能改善其中任何一项，我主要想说的是每搏输出量，这会让你的心率降低。

If you improve either of those things, and I'm gonna really focus mostly on stroke volume here, that will allow your heart rate to drop.

我们经常看到，任何形式的体育训练，尤其是耐力训练，都会让静息心率下降。

And so one of the classic adaptations we see of any type of physical training, but think more specifically endurance type training, is a reduction or a drop in resting heart rate.

你看，你现在坐着听我说话的时候，身体所需的氧气量，无论你是否健康，其实是一样的。

See, at rest right now as you're sitting here listening, the amount of oxygen required is the same whether you're fit or unfit.

这并不太重要。

It doesn't necessarily matter.

身体对氧气的基本需求，主要取决于你的体型和其他因素，和你的体能水平关系不大。

There's a minimal amount of oxygen based on your body size and other factors that don't really matter your fitness level.

我们把这个叫作心输出量。

And so we call that your cardiac output.

明白吗？

Okay?

心输出量就是每搏输出量乘以心率。

So what that is, is it's the stroke volume multiplied by your heart rate.

每次心跳泵出多少血，一分钟内跳多少次？

So how much is coming out per pump and how many times are you pumping in a given minute?

把这两个数字乘起来，就是心输出量。

You multiply those together and you get a cardiac output.

我们就假设这个数值是每分钟五升。

Let's just say that number is five liters per minute.

这是非常典型的静息心输出量。

It's a very standard resting cardiac output.

如果你体能好，我们提升了每搏输出量，而总的需氧量——也就是这个公式的后半部分——还是每分钟五升，但我增大了其中一个数，就能让另一个数减小。

If you are fit and we improve your stroke volume, since the total demand, again the back end of this equation is still five liters per minute, but I've increased one of the numbers that allows me to decrease the other number.

所以你的心率，就像我之前说的，窦房结会关注很多因素，其中之一就是前负荷。

And so your heart rate as I said, the SA node is paying attention to many things and one of them is that preload.

也就是回流到心脏的血量、泵出去的血量，还有其他一些因素。

So how much blood is coming back in and how much is going back out and various other factors.

所以它知道，如果每次心跳能泵出一百毫升血，就不需要跳得那么频繁了。

So it knows if I'm getting say this 100 milliliters of blood out per pump, I don't have to pump as often.

所以增加乙酰胆碱的信号，让心率慢下来，放松一点。

So increase the acetylcholine drive, slow the heart rate down and let's chill out.

事实上，我们稍后会聊一些具体数据，比如正常心率是多少，历史上见过的最低纪录，为什么心率太高或太低都不好，诸如此类。

Fact, we'll cover some of these numbers later about what a good heart rate is, what the best we've ever seen, why you don't wanna be too high or too low and stuff like that.

但大致就是这么个原理。

But that's basically what's happening.

有了这个理解，我们就能判断问题出在每搏输出量、心输出量，还是心率上。

And so we can identify whether or not we're struggling in either the stroke volume portion, the cardiac output side of the equation or heart rate just based on that understanding of how the heart works.

这会帮助我们确定该采取哪种训练方式，才能最有效地提升心率，更重要的是提升最大摄氧量。

That will then tell us what style and type of training we need to do to make the most efficient improvements and not only our heart rate, but more importantly our VO2 max.

你的心率——也就是静息或运动时每分钟跳多少下——能提供非常关键的信息。

Now your heart rate, again how many beats per minute you're using at rest or during exercise is incredibly telling.

就像我之前说的，最大心率本身并不会因为锻炼而改变。

As I mentioned earlier, it doesn't actually change though in response to exercise training at its maximum.

在这种情况下，真正起决定作用的只有你的年龄。

The only really thing that matters in this particular case is your age.

我们知道，随着年龄增长，最大心率会下降，但受健身水平影响并不大。

And we know that maximum heart rate goes down as you get older, but it doesn't alter that much with fitness.

不过，它能告诉你的信息包括心率变异性。

And so what it can tell you though are things like your heart rate variability.

我们就以每分钟60次心跳为例吧。

And so let's just use the example of a heart rate of 60 beats per minute.

你可能会想，如果我的心率是每分钟60次，那就意味着每秒跳一次。

So one would think and assume that if my heart rate is 60 beats per minute, that means I'm having 60 beats in sixty seconds.

每秒一次心跳。

That would be one beat per second.

如果你算一下这一分钟内总共跳了多少次，确实就是60次。

And if you calculated the total amount of beats you had over the course of the minute, you would in fact achieve 60.

这个数字就是这个意思。

That's what that number means.

但它并不一定意味着心跳是完全均匀的。

But But it doesn't necessarily mean it's on the exact same rhythm.

所以它不会像节拍器那样均匀。

So it would not be like on a metronome.

你的心脏并不会每秒都精准地跳一次。

Your heart would not be beating every second on the second.

心跳之间的间隔其实是会有变化的。

There is a variability in the space between heartbeats.

虽然到一分钟结束时，总次数还是60下，但可能连续跳两三下，然后稍停一下，再停一下，接着来一下快的，再连着五下，等等。

So while you, again, you would achieve the same number by the end of the minute, in this case, 60, it might do two or three fast ones in a row, have a little bit of a pause, have a little bit of a pause, a fast one, five fast ones, etcetera.

所以这个速率本身是有波动的。

So there's a variability in that rate.

不过这种波动非常短。

Now it's not very long.

实际上小到你根本察觉不到。

It's actually so small that you won't even be able to perceive it.

但我们可以通过多种技术来测量这种变化。

But we can measure this with a number of different technologies.

这叫做心率变异性。

This is called heart rate variability.

你可能以前听说过。

You may have heard of it before.

这个概念已经存在六十多年了，有大量的研究和证据支持。

It's been around for over sixty years and there's extensive evidence and research on this.

最初，大部分研究还是来自疾病与健康模型。

Originally, most of the work there again came from these disease and health models.

心率变异性与心血管健康、死亡风险、心理健康、抑郁和焦虑都有关联。

HRV has been associated with cardiovascular health, mortality, mental health, depression, anxiety.

但对我来说更重要的是，后来心率变异性开始被应用在运动员状态、恢复、睡眠和表现这些领域。

But more importantly for me was when HRV started coming along for things like athlete readiness, recovery, sleep and performance.

就像往常一样，生理机制就是生理机制，朋友们。

And so as always the case, physiology is physiology friends.

如果它出了问题，那就是真的出了问题。

If it's dysfunctional, it's dysfunctional.

如果你长期健康受影响，短期表现也下滑，这其实是一回事，对吧？

If you're leading that to long term health implications, if that's leading to short term performance detriments, it's really the same thing, right?

所以关于HRV的作用，我们后面几期得深入聊聊。

So understanding the role of HRV is something we're gonna have to get into a lot later in future episodes.

我很想再跟你详细说说这个话题。

I would love to talk to you more about that.

这里面有很多细节和有趣的地方值得挖掘。

There's a lot of nuance and interesting things we can pull there.

但总的来说，这是我们需要关注的关键点。

But globally something we want to pay attention to.

接下来我们进入下一部分，讲讲那三个I：我该怎么评估自己当前的心血管健康状况？

So as we go into our next section here, where we cover those three I's, how do I investigate my current cardiovascular fitness?

我该怎么判断这个水平是好是坏？

How do I interpret how good that is?

然后，我该怎么去改善？

And then how do I intervene?

那我该怎么办？

What do I do about it?

我想强调一点，光看你的最大摄氧量是不够的。

I want to make the point that just looking at your VO2 max is not enough.

光看你的静息心率也不够。

Just looking at your resting heart rate wouldn't be enough.

你还需要特别关注心率变异性，以及其他一些因素，比如呼吸频率。

You would also wanna pay tremendous attention to your HRV and then various other factors like your respiratory rate.

关于呼吸频率，我以后再详细讲。

Again, I'll do respiratory rate in a future episode.

我真想跟你聊上好几个小时这个话题。

I would love to talk to you for many hours about that.

我现在就先透露一点剧透吧。

Would actually tell you right now a little bit of a spoiler alert.

我觉得这是所有指标里最被低估的一个。

I think that is the most underappreciated of all these metrics.

我觉得它应该被视为一项生命体征，也是你衡量整体健康和体能时最重要的指标。

I think it should be considered a vital sign and is potentially the most important thing that you can measure for overall fitness and health.

老实说，在所有这些指标里，我每天最关注的就是它。

And quite honestly, it's the thing I pay the most attention to on a day to day basis of all of these metrics.

关于这个，我们稍后再详细说。

More on that later.

不过现在你得先忍一忍。

You're gonna have to wait for now though.

我想先插个广告，感谢我们的赞助商。

I'd like to take a quick break and thank our sponsors.

今天这期节目由Momentous赞助播出。

Today's episode is brought to you by Momentous.

Momentous生产安全、高品质的营养补充剂。

Momentous makes safe, high quality supplements.

我天生就不喜欢，也根本不信任大多数营养品公司，这可不是没道理的。

Now I naturally despise and frankly don't trust most supplement companies and for good reason.

事实上，我最近合著了一篇2023年发表的综述文章，发现补充剂中掺假的情况极其严重——这些掺假包括意外污染，或者故意添加本不该存在的兴奋剂、类固醇等成分，还有标签造假，比如实际含量远高于或远低于包装上标注的数值。

In fact, I recently co authored a review article that was published in 2023, in which we found that the amount of adulterations, which are accidental contaminants or deliberate spiking, like adding stimulants or anabolic or other agents which are not supposed to be in the product, or mislabeling, in which the supplement contains either a far greater or lower concentration than is being reported on the label is shockingly high.

所以我真的花了好几年时间，仔细调查了Momentous这家公司以及他们的管理团队，才在去年决定正式与他们合作。

So I actually honestly spent literally years vetting both Momentous and their leadership team before deciding to officially partner with them last year.

邀请他们成为节目的赞助商，其实是双方合作关系水到渠成的结果。

Bringing them on as a sponsor for the show was this a natural evolution of our partnership.

我之所以这么做，是因为他们真心想整顿整个补充剂行业。

Now I did all that because of their dedication to cleaning up the supplement industry.

我也亲眼看到他们为此不惜投入真金白银。

And I've seen them do that with their pocketbook.

首先，Momentous的每一款产品都经过第三方检测，而这笔开销可不低。

First, every single Momentous product is third party tested and that's expensive.

而且很多产品还进一步获得了运动类NSF认证。

And many are even further NSF certified for sport.

但更难得的是，他们对这个本就混乱的行业未来该走向何方，有着清晰的愿景。

But more unique than that is their vision for the future of where this frankly dysfunctional industry should go.

比如，他们最近推出了一项叫作‘Momentous标准’的计划，我特别期待以后跟你们详细聊聊。

For example, they've recently started an initiative they called the Momentous Standard, which I can't wait to tell you more about down the road.

除了这些坚定的道德理念，他们的产品本身也做得非常出色。

On top of this strong ethical company value, their products are also fantastic.

很多顶尖运动员和团队都在用，包括无数职业球队、奥运代表队、32支NFL球队里的31支，还有不少国防部人员，等等。

They're used by the best of the best, including countless professional teams, Olympic committees, 31 of the 32 NFL teams, many members of the Department of Defense, and many more.

当然，你们完全不用非得吃营养补充剂。

Now, none of you have to use supplements.

如果你们不想用，我真心希望你们别感到任何压力。

And I genuinely hope you never feel pressured to do so if you don't want to.

再怎么说，天然食物的重要性也远超任何补充剂。

And supplements will never be more important than whole foods.

我接触过很多运动员和企业客户，他们因为各种原因完全不用补充剂，但也取得了很好的效果。

And I've had great success with plenty of athletes and executive clients who do not want to use any supplements for whatever reason.

不过，对某些人来说，补充剂确实能带来帮助。

However, they can be beneficial to some.

所以如果你打算使用补充剂，我强烈建议选择像Momentous这样的品牌，依我看，它在安全性和品质标准上是全球最高的。

So if you're going to use them, I strongly encourage choosing a brand like Momentous, which in my opinion has the highest safety and quality standards in the world.

如果你想试试Momentous，可以去libmomentous.com/perform，下单享受八折优惠。

If you'd like to give Momentous a try, go to libmomentous.com/perform to get 20% off your order.

再次提醒，访问libmomentous.com/perform，就能享受八折优惠。

Again, that's libmomentous.com/perform to get 20% off.

本期节目还由LMNT赞助播出。

Today's episode is also brought to you by LMNT.

LMNT是一种电解质饮品粉，钠、钾、镁的比例非常理想，而且完全不含糖。

LMNT is an electrolyte drink mix that has an ideal ratio of sodium, potassium and magnesium, but has no sugar.

电解质对保持身体水分平衡至关重要，这一点我已经强调很多年了。

Electrolytes are critical to proper hydration, which I've been harping on for years.

但光靠喝水是做不到的。

But you can't do that by only drinking water.

事实上，很多人可能还记得，早在2020年，我就在YouTube的补水优化系列里介绍过LMNT了，那会儿这个播客都还没诞生呢。

In fact, many of you will probably remember that I featured LMNT in my YouTube series on optimizing hydration all the way back in 2020, which is obviously long before this podcast even existed.

我早就一直是Element的粉丝了。

So I've been a fan of Element for a long time.

事实上，细心的听众应该也注意到了，这些关于补水的视频正是加尔平补水公式的起源，这个名称不是我起的，而是来自那位传奇的神经科学家安德鲁·休伯曼博士。

In fact, astute listeners will also realize these hydration videos were the genesis of the Galpin hydration equation, named not by me, but by the legendary neuroscientist, Doctor.

安德鲁·休伯曼。

Andrew Huberman.

我当时在这些视频里推荐LMNT，是因为它的配方——一千毫克钠、两百毫克钾、六十毫克镁——在市场上真的独一无二，而且有扎实的科学依据。

I featured LMNT in these videos because their blend of a thousand milligrams of sodium, two hundred milligrams potassium and sixty milligrams magnesium really is different than any other electrolyte on the market and has great scientific support.

但我必须说得特别清楚。

However, I want to be ultra clear.

一千毫克的钠含量很高，并不是每个人都需要这么多。

One thousand milligrams of sodium is a lot and not everyone needs that much.

如果你平时不运动、不出汗，饮食中本身盐分就很多，比如吃很多加工食品，或者有钠相关的健康问题，那这个量可能就太多了。

In fact, that may be way too much if you don't exercise or sweat much, already eat a lot of salt in your diet, say from a lot of processed foods, or otherwise have sodium related medical concerns.

我个人经常用柑橘味和西瓜味的来提前补水，尤其是在要进行一整天训练、长途徒步或者狩猎之前。

I personally use the citrus and watermelon flavors a ton to prehydrate before heading out on a full day of training or a long hike or a hunt.

因为我知道自己会大量出汗，而且一路上也没多少机会补充水分。

Since I know I'll be losing a bunch of fluids and won't have many opportunities to take things with me.

Element 最近还推出了一款全新的气泡饮料，我特别喜欢。

Element has also just released a new line of can sparkling Element, which I am all about.

如果你想试试 Element，可以去 drinklmnt.com/perform，购买任何一款 Element 饮品混合粉，就能免费获得一份试用装。

If you'd like to try Element, you can go to drinklmnt.com/perform to claim a free Element sample pack with the purchase of any Element drink mix.

再次提醒，去 drinklmnt.com/perform 领取免费试用装。

Again, that's drinklmnt.com/perform to claim a free sample pack.

好了，现在我们回到一开始的那个问题：你为什么要呼吸？

Okay, we're now at the part of our conversation where I can answer the question we started off with, which is why do you breathe?

我们之前聊过，是因为需要氧气。

And we talked about how it's oxygen and we need that.

但其实氧气本身并不是代谢的燃料。

Well, oxygen is not really a fuel for metabolism.

它只是参与有氧代谢的过程，真正的能量来源其实是脂肪和碳水化合物。

It's needed to go through aerobic metabolism, but the fuel is coming from your fat and carbohydrates.

我只在进行有氧代谢时才需要氧气，但我无氧能力很强，这意味着我不靠氧气也能产生能量。

I only need oxygen during aerobic metabolism, but I'm very effective at anaerobic, which means I can produce energy without the need of oxygen.

但要完成这些过程，我还是得有氧气在身边。

But to finish those processes, I've got to have the oxygen around.

所以这里其实有个小转折。

And so it's a little bit of a twist here.

这也解释了为什么即使你是无氧型运动员，依然非常重视有氧系统——因为只有靠它，你才能彻底代谢掉碳水化合物，完成整个过程，让身体恢复到平衡状态。

This is also explaining why even if you're an anaerobic athlete, you still care deeply about your aerobic system because this is what allows you to recover, to completely metabolize your carbohydrates, to finish that process and restore yourself back to homeostasis.

你恢复得越快，就能越快地再次进行无氧运动。

The faster you can do that, the faster you can repeat your anaerobic processes.

你能更快恢复，更快回到训练和比赛当中。

You can recover, you can get back to training, get back to competition.

练得越多，就越熟练，表现也就越好。

The more you practice, the better you get, the better you perform.

所以真正发生的情况其实是这样的。

And so what's actually fully happening is this.

你吸气的时候，吸入的物质有很多，但最主要的是氧气。

When you take a breath in and you inhale, you're bringing in amongst other things, but primarily oxygen.

呼气的时候，你排出的是二氧化碳。

When you take a breath out, you're breathing out CO2.

你吸入的氧气，主要是为了调节身体的新陈代谢过程。

The oxygen you bring in is primarily there to regulate metabolic processes.

但你呼出的二氧化碳，是在调节体内的酸碱平衡。

But the CO2 you're exhaling is regulating your pH.

身体会调控很多东西，但其中有一项特别关键。

Now there's a handful of things your body will regulate almost anything else.

其中之一就是体内的酸碱值。

One of them is your pH.

它绝对不允许这个值出任何差错。

It does not like to mess with this.

如果你看看其他指标，比如血糖，就会发现它的波动其实很大。

If you were to look at other markers like say your blood glucose, you realize that that's highly variable.

血糖水平可能低到每分升70毫克，运动时甚至能升到150左右。

It can be as low as 70 milligrams per deciliters, high as 150 during exercise or something like that.

所以你看到，血液里的血糖量可能翻倍，甚至增加两倍。

And so you can see it'll double or maybe even triple the amount in the blood.

但pH值绝对不能这样波动。

You would never do that with pH.

它的正常范围非常窄，身体绝不会让它超出这个界限。

It has an extremely tight window that it will not move out of.

这是因为所有参与代谢过程的酶，都必须在特定的pH范围内才能正常工作。

That's because all the enzymes that are required for you to go through any metabolic process need to be in a certain pH range.

一旦偏离这个范围，血液太酸或太碱，酶就失效了，能量没法生成，人会很快死亡。

If it gets out of that, becomes too acidic or too alkalitic, they can't function, you can't create energy, you're going to die very very quickly.

所以，维持pH值在狭窄范围内至关重要。

So pH is insanely important to hold into a tight window.

因此，你并不会因为缺氧而感到喘不过气或迫切想呼吸。

And so what happens is you don't feel that air hunger or that desire to breathe because oxygen starts getting low.

记住，哪怕在休息时，甚至运动时，你的身体也能无氧产生能量。

Remember, especially at rest or even during exercise, you can produce energy anaerobically.

所以当你缺氧时，身体就会自动切换到无氧代谢模式。

So when you start getting low on oxygen, you'll just switch to anaerobic metabolism.

这根本没必要让你恐慌、焦虑，或者改变你的行为。

It's not necessarily a reason for you to panic, to stress, or to change your behavior.

但二氧化碳水平上升，就会引发那种反应。

Increases in CO2 though will do that.

记住，无论你的肌肉是靠脂肪还是碳水化合物供能，

And so remember, your muscle is whether it's using fat as a fuel or carbohydrates as a fuel.

它最终都是为了生成一种叫ATP的分子。

It's trying to generate a molecule called ATP.

这是所有生物体内的通用能量货币。

This is the energy currency in all of biology.

至于你用这些ATP来做什么，其实并不重要。

And it doesn't matter what you use that ATP for, by the way.

不管是骨骼肌、心肌，还是其他任何肌肉，都没关系。

It doesn't matter if we're talking about skeletal muscle, we're talking about cardiac muscle or anything else.

不管你是为了运动、给大脑供能、恢复体力，还是消化食物，这些都不重要。

So whether you're using this for exercise, to power your brain, to recover, to digest food, it's irrelevant here.

我们会用碳水化合物或者脂肪作为燃料。

We're gonna use carbohydrates or fat as a fuel.

我们会生成ATP。

We're gonna make ATP.

最终，所有代谢过程的产物都是水、二氧化碳和ATP。

And then at the end, the final product of all metabolism is going to be water, CO2 and ATP.

随着代谢率上升，体内的二氧化碳浓度也会升高。

So the CO2 concentration increases as metabolic rate increases.

因此，二氧化碳会从组织进入血液。

As a result of that, you start then moving CO2 from your tissue into the blood.

血液中的二氧化碳浓度随之上升。

Concentrations of CO2 then in blood go up.