When people lift weights and their muscles get bigger, their cells make more of the tiny machines (ribosomes) that build muscle proteins — and the people who gain the most muscle tend to make the most of these machines.

When you lift weights, your muscles make more of the tiny molecular machines that build proteins, which helps them grow bigger.

Lifting weights makes your muscles bigger and stronger, and this happens because your muscle cells start making more of the tiny machines that build proteins.

When you lift weights, your muscles grow bigger because your cells first make more protein-making machines (ribosomes) — and the more of these machines you build, the more your muscles grow.

Some people’s muscles grow way more than others when they lift weights, and this might be because their muscle cells make more of the tiny machines (ribosomes) that help build muscle protein.

When older people do strength training for four weeks, those who get much bigger muscles also see a big jump in the cellular machinery that helps build muscle, while people who don’t gain muscle don’t see this change—so it seems like making more of this machinery is tied to getting stronger and bigger.