People who naturally have a longer lever arm between their kneecap and knee joint tend to get stronger in eccentric movements (like lowering a weight) after training, likely because their anatomy...

Men who started with a longer tendon lever arm and could already activate their thigh muscles better tended to get stronger in eccentric movements after training — their starting point mattered.

Lifting weights slowly (eccentric) or quickly (concentric) both make your quads stronger in about 10 weeks — and you don’t need to be sore or damaged to get stronger.

In healthy men aged 69–70, performing supervised slow resistance training with moderate to heavy weights for 12 weeks leads to small but measurable increases in the thickness of the patellar and Achilles tendons.

When untrained men get stronger during dynamic leg extensions, the biggest factor is how much they can turn on their thigh muscles — bigger muscles and fiber angles help a little, but turning on the muscles harder matters most.