Interesting correlation. There is an FDA-approved device for snoring/Obstructive sleep apnea (exciteOSA) that states it works by helping to change fast-twitch muscle fibers in the tongue to slow ones, allowing more resistance to fatigue causing the tongue to drop back at night.
They say one cause of apnea (soft palate issues are another) are stronger but less fatigue-resistant tongue muscles, so their machine electrically stimulates the tongue for 20 minutes a day to make it more resistant by converting to more slow-twitch muscles.
They cite two studies, see below, which includes quadriceps testing. Of interest if anyone has heard of this used in cycling.
- Nuhr M, Crevenna R, Gohlsch B, Bittner C, Pleiner J, Wiesinger G, Fialka-Moser V, Quittan M, Pette D. Functional and biochemical properties of chronically stimulated human skeletal muscle. Eur J Appl Physiol 2003;89:202-208