I see a lot of claims about what happens with the fascia.
It generally takes about 8 minutes for the collagen fibers to begin to lengthen, aka plasticity. This takes a lot of discomfort to achieve.
For less intense and shorter stretching, you’re squeezing the fascia. In the technical sense, your fascia is being stretched, but only elastically.
When you work on your fascia, you’re likely working on the ability for the fascia to glide.
Stretching the fascia stimulates production of collagen along the line of tension, but not more elasticity.
It does not “break up adhesions” or scar tissue. Collagen fibers are very strong and require a lot of force or time to break or stretch.
What is more likely is the fascia is being rehydrated from mechanical squeezing and pulling, helping to refresh and replenish the fascia with fluids.
In other words, you’re treating the tissues like a sponge, squeezing out the water-glycosaminoglycan (GAG) mixture and then rehydrating when the stretch has finished.
This is still beneficial for healthy fascia. The fluids are what allow you to move instead of sticking to yourself.