Lots of studies support stretch-mediated hypertrophy: muscles grow more when put under tension while lengthened.

I have a mental model for why this might be the case.

The load on a muscle under tension is spread out over the cross section of the muscle, perpendicular to the direction of the load.

When a muscle is shortened, it bunches, spreading out the load over a larger cross section.

When a muscle is lengthened, it stretches, concentrating the load over a smaller cross section.

Imagine two Muscles in your body, one shortened, one lengthened, lifting a 100 pound Load from the floor.

The shortened muscle is on the left, and the lengthened muscle is on the right:

MM    M
MM    M
|     M
L     M
      |
      L

In this very unrealistic diagram, the cross section of the shortened muscle is two M "units" and the cross section of the lengthened muscle is one M "unit", so the shortened units of muscle each experience 50 pounds of load, and the lengthened units of muscle each experience the full 100 pound load.

If mechanical tension on muscles is the most significant cause of hypertrophy, then we want to concentrate it by stretching the muscle, as opposed to spreading it out by bunching the muscle.

I have no idea if this model is actually true, but it makes sense to me!