If you're new to working out, doing elbow curls by slowly lowering the weight (eccentric) faster than you raise it (concentric) might make your biceps grow bigger than doing the same movement slowly or just lifting fast.

If you're new to lifting weights, doing exercises where you lower the weight slowly (eccentric) might make your biceps grow bigger than exercises where you lift the weight up (concentric), after 8 weeks of training.

If you're new to lifting weights, doing slow eccentric moves (like lowering a weight slowly) at a slow speed might build more muscle than doing fast concentric moves (like lifting quickly), but not more than slow concentric moves — so speed matters differently depending on whether you're lowering or lifting.

If you're new to working out and do leg exercises where you lower the weight slowly and quickly, doing it at a speed of 180 degrees per second might give you the biggest strength gains after 8 weeks — faster eccentric moves might just be the secret sauce for getting stronger.

When people who don't normally lift weights do a tough arm exercise twice, four weeks apart, their biceps don't stretch as much the second time, even though they're trying just as hard.

Doing bicep curls only halfway up (keeping the arm stretched) might make the lower part of your bicep grow a tiny bit more than doing full curls, but the difference is very small.