Lifting heavy weights regularly is needed to get the most strength gains in exercises you practice, because doing lighter weights until tired gives less strength boost even if muscles grow the same size.

Lifting heavy weights for just a few reps makes you stronger in exercises that work one muscle at a time, more than lifting lighter weights for many reps, especially if you already work out regularly.

Lifting heavier weights makes you stronger and improves your brain-muscle connection more than lifting lighter weights, even if you do the same total amount of work and build the same muscle size.

Doing a light warm-up set before lifting heavy weights might help you build more muscle and get stronger, according to some research that tried a similar but different approach.

The total amount of work done (weight × reps × sets) seems to matter for muscle growth — more work generally leads to more muscle, even if the weights are light.

When lifting lighter weights, pushing until you can't lift anymore helps build bigger muscles, but this doesn't happen with heavier weights. Heavier weights always build more strength than lighter ones, no matter how hard you push.