When you get stronger holding a position (like pushing against a wall), your muscle size matters more — but when you’re moving (like kicking a ball), how hard you activate your muscles matters more...

When young men do isometric leg exercises for 12 weeks, their thigh muscles get bigger—and that bigger muscle size helps explain about 1 in 5 of their strength gains, even if their nerves aren’t getting better at telling muscles to work harder.

Doing a lot of stretching can make you stronger without necessarily making your muscles bigger. This suggests the strength gains come from your nervous system and muscle structure working better together, rather than just from building more muscle mass.

Just because certain muscle traits make someone strong right now doesn’t mean those same traits will help them get stronger from training—what matters for improvement is different.

Just because your muscles get bigger from lifting weights doesn't mean you'll get much stronger — the two don't really go hand in hand.

Whether you do CrossFit or lift weights regularly, your thigh muscles end up about the same size after years of training.