You're Not That Big. So How Are You Lifting That?

“How do you squat 200kg? You’re not even that big.”

I have heard some version of that sentence more times than I can count. It is a fair question, and it comes from a reasonable assumption: more muscle should mean more force. Look at the muscle, estimate the force.

It is also wrong, or at least much less true than people think. Muscle cross-sectional area sets a ceiling on how much force a muscle can theoretically produce. It does not determine how much of that ceiling you actually get to use. The gap between the two is filled by something nobody can see by looking at you: how well your nervous system recruits the muscle, how fast it fires it, and how well it coordinates everything working together.

The signal, from brain to fiber

Every contraction starts as an electrical decision, not a muscular one.

The motor cortex sends a signal down the spinal cord to an alpha motor neuron. That motor neuron, together with every muscle fiber it connects to, forms a motor unit. When the signal reaches the neuromuscular junction, it triggers an electrical impulse that spreads across the muscle fiber membrane and down into the fiber itself, through a network of tubules that reach deep into the cell. That impulse causes the sarcoplasmic reticulum, the fiber’s internal calcium store, to release calcium into the cell. Calcium is what unlocks the contractile machinery, allowing the fiber to actually generate tension.

Strip out the detail and the chain is simple: nerve signal, electrical impulse, calcium release, contraction. The muscle is the last step. Everything that determines how strong that contraction is happens before the fiber ever shortens.

Not all motor units are recruited the same way

The nervous system does not activate all of a muscle’s motor units at once, and it does not activate them randomly. It follows an order, known as Henneman’s size principle: the smallest motor units, the ones controlling slow, fatigue-resistant fibers, get recruited first. As the demand for force increases, progressively larger motor units join in, up to the largest ones, which produce the most force but fatigue quickly and are normally reserved for near-maximal efforts.

This matters because it means your biggest, most powerful motor units are only recruited when you actually demand near-maximal force from the muscle. Train at moderate intensity forever, and you may rarely, if ever, recruit the motor units responsible for your highest force output. They exist. They are simply never called.

How hard each unit fires matters just as much

Recruitment answers which motor units are active. It does not answer how much force each one is producing at a given moment, and that is where discharge frequency comes in.

A single nerve impulse produces a single twitch, a quick rise and fall in tension. Fire that same motor unit repeatedly, fast enough, and the twitches start to overlap and summate, eventually fusing into a smooth, sustained, much higher level of tension: tetanus. The same motor unit, recruited the same way, produces very different force depending on how rapidly it is being fired.

So the nervous system has two separate levers to increase force: recruit more motor units, and fire the ones already recruited faster. Both have to move together to get near-maximal output, and both are trainable.

Why the nervous system holds back on purpose

If near-maximal effort requires full recruitment and high firing rates, the obvious question is why anyone would ever have access to less than their full capacity. The answer is that the nervous system is deliberately conservative, for good reason.

Muscle spindles and Golgi tendon organs sit inside the muscle and tendon, constantly monitoring length and tension. Push a joint into an unfamiliar range and a spindle can trigger a protective reflex. Push tension high enough and a Golgi tendon organ can trigger autogenic inhibition, actively damping the signal to the muscle before tension reaches a level the system considers risky for the tendon or the joint. This is not a flaw. It is a safety system, and it means a large share of what looks like “strength training” is really training the nervous system to trust that a given level of tension is safe, so it stops pulling the brake as early.

This is also why maximal voluntary force so often falls short of true physiological capacity. The muscle can often produce more than the nervous system is currently willing to ask for.

Why a bigger muscle does not guarantee more force

This is the part that actually answers the original question. Cross-sectional area and the ability to express force train in different directions, and most training programs only pull on one of them deliberately.

A bodybuilder’s training is, by design, built around high time under tension, moderate loads, and enough fatigue and metabolic stress to drive a strong hormonal and structural growth response. That is an excellent recipe for building muscle. It is not the same stimulus that trains the nervous system to recruit maximally, fire at high frequency, and coordinate efficiently under a true one-rep effort. The result is real strength, but a strength-to-size ratio that stays comparatively low, because the training never specifically asked the nervous system to express everything the muscle could theoretically produce.

I was the opposite case for most of my competitive years: lean, not visibly muscular, and strong well out of proportion to how I looked. Sprint training is built around repeated near-maximal and maximal efforts at low volume, exactly the stimulus that drives recruitment, discharge rate, and coordination hard, without the volume of time-under-tension work that would have added much muscle mass. Same nervous system principles, pointed at a completely different training target, produce a completely different-looking athlete with a completely different strength-to-size ratio.

The piece that ties it together: coordination

None of this works in isolation. A heavy squat is not one muscle contracting maximally. It is hips, knees, ankles, and trunk bracing, all needing to fire in the right sequence, with the right muscles contributing force and the right ones staying out of the way. Poor intermuscular coordination means some of the force your muscles do produce gets wasted fighting against itself, through mistimed co-contraction or an inefficient movement pattern, instead of moving the bar.

This is also why bar velocity is such a useful window into all of this. In velocity-based training, the number on the screen is downstream of everything described above: how many motor units got recruited, how fast they fired, and how well they worked together. And it is exactly why the sticking point discussed in the article on accommodating resistance exists in the first place: the joint angle where mechanical disadvantage and the limits of recruitment and coordination overlap the most.

So the honest answer to “how are you lifting that and you’re not even that big” was never about the muscle. It was years of training a nervous system to stop holding back.