When I get home at the end of the day, Robb tends to be "finished" for the day. Either he has worked with the therapist, or he has been to the therapy gym. In either case, he tends to be experiencing spasticity, and is having trouble walking.
I've been trying to get a handle on what, exactly, spasticity is, and why Robb is having so much of it lately. When Robb stretches his body, one things that happens is "neural glide." The un-elastic nerve cells are encased in a sort of sheath, and when Robb stretches, they get slide around inside of the neural sheath.
Think if your leg inside of your pants leg. Your clothing protects your leg, and your leg has the ability to shift and move inside of your pants. So, now imagine if there was portion of your pants leg that was damaged, either too tight, or too stiff. You still had to walk, but the pants chafed at your leg. This is sort of what is happening when Robb stretches and moves his leg muscles. The neural sheath irritates the nerve cells and as a result, Robb experiences spasticity.
So, that's an over-simplified explanation of the "why" of spasticity.
The "what" is more difficult.
When Robb is experiencing spasticity, he has a sensation of having an over-worked muscle that is clenched and that won't un-clench. He can't move the muscles very much, and they are very tired.
In Robb's case, he experiences this sensation in his lower legs, hamstrings and his butt. Because of the muscle clenching, he can barely lift his legs, and more importantly, he cannot "stride out." If Robb chose to dress as a zombie for Halloween this year, he would have a perfect walk for the costume.
Ironically, it is Robb's increased physical activity that is causing or at least aggrievating this spasticity. I just wish that my schedule allowed me to see him at the therapists, where he is having a lot of successes.