There is a medical condition involved with a tight muscle fascia. Mary Decker Slaney had it in her calves. She was a runner. Kept getting cramps in the calves. They did some kind of operation to split the fascia around the calf muscles giving them more room to expand. If there is more room conceivably they could grow larger.
Here's a comparison on muscle fascia:
Kill an old animal and a young animal, skin it, and compare the fascia. The fascia in the old animal is kind of tough and unpliable. It kind of applies to the muscle as well. Old venison, tough to chew. The thing about stretching/tearing the fascia probably has something to do with your age. You can probably stretch/micro-tear the fascia during your growing years and get some results. Trying to stretch them when you are old might just tear the muscle tendon from the bone insertion provided you applied enough force.
Or you could just machine a long stainless steel needle with a rear cutting blade about the thickness of the fascia. Take about 4 hits of Percodan, puncture the skin at the top of the calf muscle, run the needle down to the bottom of the calf them pull it back out cutting the fascia on the way. I'd guess that's probably about the way it would be done in surgery. Not recommended by me though.