When Should You Take L Carnitine? MuscleTech Simply Herbal L Carnitine with L Tartrate Supplement for Muscle Recovery Pre Post Workout 1000mg 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 Vlado's Himalayan Organics L Carnitine Liquid 3000 mg I with Vitamin B Carbamide Forte L Carnitine Liquid 3300mg L Carnitine Supplement For Men & Women Liquid L Carnitine Pre Workout, Intra Workout & Post Workout