Alpha-glycerylphosphorylcholine(alpha-GPC) is an interesting molecule that has some interesting properties. It's a precursor to the neurotransmitter acetylcholine, which may improve cognitive function, and it can readily cross the blood-brain barrier(BBB). Many supplement companies are including it in preworkout formulas bc of 2 studies that came out last year. One study showed athletes taking 600mg 45min prior to working out noticed a 14% increase in power.
The second study is the one I find more interesting. Subjects receiving 1000mg of alpha-GPC had a 221% increase in GH levels 60 min after ingestion. While it doesn't raise GH levels all day, it can cause a huge spike right around a workout or post workout which may be beneficial for repairing muscle tissue. Another study showed a 168% increase in GH after 45 min at a dose of 600mg. Bottom line: acetylcholine is involved in tons of biochemical processes and can play a major role in everything from cognitive function, to fat oxidation, to muscle repair. Alpha-GPC is the most effective choline precursor on the marker and may have some ergogenic properties worth looking into.