How to Take L Carnitine Correctly to Boost Your Training Bodybuilding.com Cutler Nutrition Liquid L Carnitine Supplement with Acetyl L Carnitine & L Carnitine Tartrate Forms Pre Taking a preworkout AND carnitine? It is important to get the timing of each supplement right to get the best results with both. Watch as Phil explains the best way to combine them. , #preworkout I get asked so many questions about my pre workout combo, so here it is! I take Oxyshred + Acetyl L Carnitine. This combo gives me the energy I need to crush my workouts