L Carnitine vs L Arginine: Understanding Their Differences and Benefit Fitness Health Male effect of L carnitine in recovery biomarkers: (a) creatine kinase, Download Scientific Diagram L Carnitine Didn't another study show carnitine was good for the heart? Early research into L carnitine was often cited as underwhelming, showing negligible changes in muscle carnitine content and fat loss outcomes. However, these findings may have been limited by a short study window