First, don't let me scare anyone because I am not saying I have ALS , or anything else diagnosed'ed for that matter, but I do have something changing me.
I would suggest that atrophy is possible all over. I have noticed, for more than a few months, loss of bulk in most limb muscles including hands and feet, gluts, and shoulders. As of now no "denting" that is visible with severe atrophy. Did not notice as much weakness until just 3-4 months ago in a few places. Not clinical weakness, but weakness measured by my formally very active lifestyle.
I have been a very active 42-yr old, and over the last 3 months I have had to curtail many activities I enjoy due to quicker muscle fatigue, relatively minor coordination issues, muscle shaking, and cramps for days after strenuous stuff.
What's doing it? Don't know. Concerned and seeking answers? Yep.
p.s. Oh, and I have been told my symptoms are in my head. They ain't, as we say down in Jawja.