Luc van Loon is a Professor of Physiology of Exercise and Head of the M3-research unit at the Department of Human Biology and Movement Sciences at Maastricht University Medical Centre. Luc has an international research standing in the area of skeletal muscle metabolism. Current research in his laboratory focuses on the skeletal muscle adaptive response to exercise, and the impact of nutritional and pharmacological interventions to modulate muscle metabolism in health and disease. The main research interests of his laboratory include muscle metabolism, sports nutrition, clinical nutrition, adaptation to endurance and resistance type exercise, and the use of physical activity and/or nutritional interventions to improve health in chronic metabolic disease (aging and type 2 diabetes). The latter are investigated on a whole-body, tissue, and cellular level, with skeletal muscle as the main tissue of interest.
Luc has authored more than 270 original, peer-reviewed research and review articles. He is member of the Editorial Board of the International Journal of Sport Nutrition and Exercise Metabolism (IJSNEM) and the European Journal of Sport Science (EJSS). He is a member of the Scientific Board of the European College of Sport Science (ECSS) and the Benelux Association for Stabile Isotope Scientists (BASIS). To support the use of stable isotopes in biomedical research, Prof. van Loon is also scientific coordinator of the Stable Isotope Research Center (SIRC) at the Academic Hospital in Maastricht and coordinator of the Human Performance Laboratory at the Departments of Human Biology and Movement Sciences.
’You are what you just ate’
Prof. L.J.C. van Loon
Skeletal muscle protein is constantly being synthesized and broken down, with a turnover rate of about 1-2% per day. The rate of skeletal muscle protein synthesis is regulated by two main metabolic stimuli, food intake and physical activity. Food intake, or specifically protein ingestion, directly elevates muscle protein synthesis rates. The dietary protein derived essential amino acids and leucine in particular, act as signaling molecules activating anabolic pathways in skeletal muscle tissue and by providing precursors for muscle protein synthesis. Ingestion of a meal-like amount of dietary protein (~20 g) elevates muscle protein synthesis rates for several hours following ingestion, resulting in net muscle protein accretion. A substantial part of the ingested protein derived amino acids are taken up and directly used to support the post-prandial rise in muscle protein synthesis rate following ingestion of a single bolus of protein. The dietary protein derived amino acids not only present themselves as strong signaling molecules, but also act as direct precursors for de novo muscle protein synthesis. In short, ingestion of a single meal-like amount of milk protein allows ~55% of the protein derived amino acids to become available in the circulation, thereby improving whole-body as well as leg muscle protein balance. Approximately 20% of the protein derived plasma amino acids will be taken up in skeletal muscle tissue during a 5 h post-prandial period, thereby stimulating muscle protein synthesis rates and providing precursors for de novo muscle protein. In conclusion ‘you are what you just ate’. When food is ingested after a bout of physical activity the post-prandial muscle protein synthetic response is augmented, with higher muscle protein synthesis rates sustained over a more prolonged period of time. In other words, when you ingest protein following a bout of physical activity ‘you become even more of what you just ate’.