Thanks MA. My question wasn't solely based on the bioavailability, but also the absorption rate. There appears to be a small window after a carb spike/slin pin to shuttle the carnitine into the muscle.
I'm guessing the IV route was used rather than IM/SQ because it is the quickest and most reliable, while orally will leads to the slowest utilisation of lcar. IM is probably faster than oral, but I was curious if it was significant enough to justify pinning it vs taking larger scoops orally

The study I linked to showed significant results using only 1.36g of lcar pd orally.
Not arguing at all. I just find the topic interesting.