Amino Acid Kinetics in Blood After Consuming Different Milk Protein Supplements

Increasing or maintaining muscle mass is of great importance for populations ranging from athletes to patients and elderly. Resistance exercise and protein ingestion are two of the most potent stimulators of muscle protein synthesis. Both the physical characteristic of proteins (e.g. different digestion rates of whey and casein) and the amino acid composition, affects the potential of a certain protein to stimulate muscle protein synthesis. Given its superior ability to rapidly increase blood leucine concentrations to high levels, whey is often considered the most potent protein source to stimulate muscle protein synthesis. Native whey protein is produced by filtration of unprocessed milk. Consequently, native whey has different characteristics than WPC-80, which is exposed to heating and acidification. Because of the direct filtration of unprocessed milk, native whey is a more intact protein compared with WPC-80. Of special interest is the higher amounts of leucine in native whey.

The aim of this double-blinded randomized 5-arm cross-over study is to compare amino acid kinetics in blood after a bout of strength training and ingestion of 20 grams of high quality, but distinct, dairy protein supplements (native whey, whey protein concentrate 80, hydrolysed whey, microparticulated whey and milk). Furthermore, the investigators investigate whether differences in amino acid kinetics affect acute blood glucose and urea response, as well as recovery of muscle function after a bout of strength training.

The investigators hypothesize that native whey will give a faster and higher rise in blood concentrations of leucine compared to the other protein supplements.

Inclusion criteria

• Healthy in the sense that they can conduct training and testing
• Able to understand Norwegian language written and oral

Exclusion criteria

• Diseases or injuries contraindicating participation
• Use of dietary supplements (e.g. proteins, vitamins and creatine)
• Lactose intolerance
• Allergy to milk
• Allergy towards local anesthetics (xylocain)