The limitations to fatty acid oxidation in the transition from moderate.. - Prof. Helge 

Invited Session at ECSS MetropolisRuhr 2017 "Muscle Carnitine: The Key Player in Muscle Fuel Selection?"
The limitations to fatty acid oxidation in the transition from moderate to high intensity exercise in humans and
the mechanistic basis of this limitation
Helge, J.
University of Copenhagen
Fatty acids utilised during exercise originate from circulation or from muscle triglyceride stores. Despite increasing rates of energy
demand during incremental exercise total fatty acid oxidation is suppressed at high intensities to below that observed during
moderate intensity exercise. Although this has been known for many years, the mechanisms behind this phenomenon are still not
fully elucidated. The failure of adipose tissue to deliver sufficient fatty acids to exercising muscle has been proposed, but evidence
has emerged that muscle centric factors may be of greater importance. The high rate of glycolysis during high intensity exercise might be the principal driver via increased pyruvate dehydrogenase flux and production of acetyl-CoA, which in turn is buffered by carnitine to form acetylcarnitine. This will lead to decreased availability of free carnitine for long chain FA transport into mitochondria.
This presentation, will be setting the scene and summarising our current understanding on how fatty acid metabolism is regulated
during exercise. It will especially focus on the limitations to fatty acid oxidation in the transition from moderate to high intensity exercise in humans and the mechanistic basis of this limitation.