Those relationships are small motor units.

这些关系是小的运动单元。

What does the size of a motor unit determine?

运动单位的大小决定了什么？

Those thousand fibers together form a large motor unit.

这上千条纤维共同构成了一个大的运动单位。

Alright, so what you're listening to, so this is your motor units happening right here.

你现在听到的，这就是你的运动单元正在此处发挥作用。

I've got two words for you: motor units.

运动单元。

So to increase the contraction force and tighten her grip, she can recruit another motor unit.

所以为了增加收缩力，收紧她的握力，她可以招募另一个运动单元。

Then some larger motor units with larger fibers are enlisted, increasing the strength of contraction.

然后使用一些更大纤维的更大电机单元，增加收缩强度。

And remember, all of this twitching happens in individual motor units.

记住，所有这些抽搐发生在单个的运动单元中。

It starts when the smallest motor units with the smallest fibers are activated by your most excitable neurons.

当你最易兴奋的神经元激活具有最小纤维的最小运动单元时，它就开始了。

A motor unit is a group of muscle fibers that all get their signals from the same, single motor neuron.

运动单元是一组肌肉纤维，它们都从同一个运动神经元接收信号。

So the basic rule is: the more motor units recruited, the greater the force that's generated.

调动的运动单位越多，产生的力就越大。

The bigger the challenge becomes, the bigger the brain's signal grows, and the more motor units it rallies to help you achieve your task.

动作难度越大，大脑发出的信号越强，协助完成动作所调动的遥控神经单位越多。

This is a process called recruitment, or multiple motor unit summation. And it's where some of your muscles' more nuanced abilities come in.

这是一个叫做招募的过程，或多个运动单元求和。这就是你的一些肌肉更微妙能力的来源。

Mechanistically, this difference might be explained by caffeine's connection to improving motor unit recruitment, or the ability of your brain and muscles to communicate and contract your muscle fibers.

从机制上讲，这种差异可能是因为咖啡因与提高运动单位募集有关，或者是与大脑和肌肉交流和收缩肌肉纤维的能力有关。

And when a motor unit, no matter how large or small, responds to a single action potential, those fibers quickly contract and release, in what we call a twitch.

当一个运动单元，不管大小，对单个动作电位做出反应时，这些纤维会迅速收缩和释放，我们称之为抽搐。

But when we zoom out to the complete muscle of maybe a thousand motor units, we can increase the strength of the stimulus by sending action potentials to more motor units.

但是当我们缩小到一千个运动单位的完整肌肉时，我们可以通过向更多的运动单位发送动作电位来增加刺激的强度。

And finally, if you want to give it all you've got — which you don't in Abby's case — your largest motor units, with your biggest muscle fibers will get involved.

最后，如果你想全力以赴——在 Abby 的例子中你没有——你最大的运动单元，和你最大的肌肉纤维都会参与进来。

So right here, these are the motor units that are happening from her spinal cord out to her muscle right here, and as she's doing it, you're seeing the electrical activity that's happening here.

就在这儿，这些就是正在起作用的运动单元，从她的脊椎延伸到这里的肌肉，伴随着她的动作，你可以看到这里的电信号活动。

Since multiple action potentials don't travel down all the motor neurons at exactly the same time, each motor unit twitches at slightly different times, which helps smooth out the … twitchiness.

由于多个动作电位不会在完全相同的时间沿着所有的运动神经元运动，每个运动单元在稍微不同的时间抽搐，这有助于消除抽搐。

We also talked about the role size plays in motor units, the three phase cycle of muscle twitches, and how the strength and frequency of an impulse affects the strength and duration of a contraction.

我们还讨论了大小在运动单位中的作用，肌肉抽搐的三相周期，以及脉冲的强度和频率如何影响收缩的强度和持续时间。