What Does L Carnitine Do In Pre Workout? L Carnitine as Pre Workout Supplement: Guide The Science of Good Health 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 How to Take L Carnitine Correctly to Boost Your Training Bodybuilding.com 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