It is really three conditions - spaghetti meat, woody chicken and white striping - all the result of chickens having been bred for rapid growth and size. Taste, texture and flavor are negatively affected.

This site explains them with some pictures: https://www.thepoultrysite.com/articles/woody-breast-myopath...

This is how I identify them:

1. Spaghetti Meat: Raw chicken breast fibers look like spaghetti strands. The top of the breast will look uniform. It is when I've cut into the breast that the spaghetti strands will become apparent. These breasts get boiled and fed to my dog.

2. Woody Breast: This is chicken breast that is tough in texture. Even when cooked, it feels raw or "crunchy". To me, this is really off-putting. I sometimes try to salvage raw breasts by cutting more off (also for my dog). But the taste is so off-putting that I don't care for them.

3. White Striping: You can see this before buying the breast - you'll see white lines across the breast. These breasts can be okay. But often woody breast and white striping coincide. I will cook the breasts if they only have white striping.