Learn Fat Burner vs Pre Workout Differences and Selection Guide Alpha Lion Burn20 31 Servings Fiery Punch When Should You Take L Carnitine? MuscleTech Oxyenergys L Carnitine. My go to pre post workout supplement. Pre workout I usually take it before my workout session for energy production. Post workout Ill take it the day after my 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