The aim of this study is to investigate the amino acid kinetics in blood after a bout of strength training and ingestion of different milk protein supplements (native whey, whey protein concentrate 80, hydrolysed whey, microparticulated whey and milk) The investigators hypothesize that native whey will give a faster and higher rise in blood concentrations of leucine compared to the other 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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
QUADRUPLE
Enrollment
13
Plasma amino acid concentration change from baseline
Time frame: Blood collected at 0, 30, 45, 60, 90 and 120 min after consumption of protein supplements
Serum glucose change from baseline
Time frame: Blood collected at 0, 30, 45, 60, 90 and 120 min after consumption of protein supplements
Serum urea change from baseline
Time frame: Blood collected at 0, 30, 45, 60, 90 and 120 min after consumption of protein supplements. For milk and native whey blood was collected at two additional time points: 22 and 30 hours after consumption of protein supplements
Muscle force generating capacity change from baseline
Measured as unilateral isometric knee extension force (Nm) with 90° in the hip and knee joints.
Time frame: Measured before and at 0, 6, 22 and 30 hours after exercise. Only measured after milk and native whey
Jump height change from baseline
Measured as counter movement jump on a force plate
Time frame: Measured before and at 0, 6, 22 and 30 hours after exercise. Only measured after milk and native whey
Serum creatine kinase change from baseline
Time frame: Blood collected at 0, 30, 45, 60, 90 and 120 min after consumption of protein supplements. For milk and native whey blood was collected at two additional time points: 22 and 30 hours after consumption of protein supplements
Muscle soreness change from baseline
Measured for m. quadriceps and m. pectoralis major on a visual analog pain scale
Time frame: Measured before and at 0, 6, 22 and 30 hours after exercise. Only measured after milk and native whey
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