For women new to lifting weights, doing slow reps with longer muscle contractions builds more muscle strength and size faster than regular-speed lifting at the same effort level over 6 weeks.

For older adults between 59 and 76 years old, doing gentle strength training twice a week for 12 weeks makes them stronger but doesn't build much muscle size.

Using machines or bands that change how hard they feel as you move might make your muscles work more evenly during an exercise, but that doesn’t always mean you’ll grow bigger muscles faster than with regular weights—especially if you’re just starting out.

Slowing down the lowering part of a lift (like slowly lowering a dumbbell) makes your muscles more damaged and triggers more repair and growth than quickly lowering it.

Lifting weights faster or normally gives you more strength gains than lifting weights very slowly, especially for healthy adults.

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.