Massive Confusion...

AP flour absorbs water and fully hydrates very quickly. If you knead to windowpane (enter that in the search box),the dough gives up its  starchy gel to form strong bubble walls and  the  loaf will be fluffy soft. WW takes a long time to absorb the water fully so it takes a little different technique to get the starchy gel developed so it can soften the crumb. WW dough needs time in the form of an autolyze, sponge or cold retard. THese are easy  techniques with fancy names that  are easy to understand with brief explanations. Use the search box. You'll get lots of info. The idea is that if you don't allow the WW dough time to absorb the water fully, you will not be able to develop adequate starchy gel and windowpane with kneading to make a nice soft loaf. If you continue the under-hydrated and underdeveloped dough through to baking, the dough will not be able to trap as much of the gas, form a dense crumb and after baking, the branny bits will continue to absorb moisture from the crumb. Consequently,the slices will crumble easily.

Some links:

http://www.thefreshloaf.com/node/22987/light-and-fluffy-100-whole-wheat-bread

http://www.thefreshloaf.com/node/36907/100-white-whole-wheat-sandwich-loaf-remix-method

And txfarmer's posts were great but they are old :

http://www.thefreshloaf.com/node/21575/sourdough-100-whole-wheat-oatmeal-sandwich-bread-whole-grain-breads-can-be-soft-too

http://www.thefreshloaf.com/node/23931/sd-100-ww-hokkaido-milk-loaf-oxymoron

Have some delicious fun!

This is a great recipe for whole wheat. It soaks some of the wheat for a long time (in the biga-the Italian version of flour,water and small amount of yeast), some in a "sponge" (American/European version of soaking flour), and then adds just a little whole wheat flour at the end to bring the dough to the correct consistency. The biga develops flavor as the small amount of yeast digests the flour and exudes the substances that give bread it's characteristic fermented flavor. The sponge helps soak the flour,produce flour and increase the yeast population. Try this recipe or apply the techniques to your recipe and see if there is a difference in your loaf.

https://www.geniuskitchen.com/recipe/100-whole-grain-bread-with-biga-soaker-458576

Vital wheat gluten (VWG) makes bread chewier. It really isn't needed if the flour has adequate gluten content. It doesn't have to be a high amount but it has to work well enough to support the loaf structure.

Elly's overnight-autolyse whole-wheat sourdough? It's not bad at all: https://youtu.be/jd_r69WauPk

Happy baking.

PS: I've wondered about vital wheat gluten myself, but have been reluctant to try it, since I'd understood that it could result in gummy crumb if not dosed properly.

Carole