Differences in postprandial protein handling after beef compared with milk ingestion during postexercise recovery: a randomized controlled trial.
BACKGROUND
Protein consumed after resistance exercise increases postexercise muscle protein synthesis rates. To date, dairy protein has been studied extensively, with little known about the capacity of other protein-dense foods to augment postexercise muscle protein synthesis rates.


OBJECTIVE
We aimed to compare protein digestion and absorption kinetics, postprandial amino acid availability, anabolic signaling, and the subsequent myofibrillar protein synthetic response after the ingestion of milk compared with beef during recovery from resistance-type exercise.


METHODS
In crossover trials, 12 healthy young men performed a single bout of resistance exercise. Immediately after cessation of exercise, participants ingested 30 g protein by consuming isonitrogenous amounts of intrinsically l-[1-(13)C]phenylalanine-labeled beef or milk. Blood and muscle biopsy samples were collected at rest and after exercise during primed continuous infusions of l-[ring-(2)H5]phenylalanine and l-[ring-3,5-(2)H2]tyrosine to assess protein digestion and absorption kinetics, plasma amino acid availability, anabolic signaling, and subsequent myofibrillar protein synthesis rates in vivo in young men.


RESULTS
Beef protein-derived phenylalanine appeared more rapidly in circulation compared with milk ingestion (P < 0.001). The availability of phenylalanine during the 5-h postexercise period tended to be higher after beef (64% ± 3%) ingestion than after milk ingestion (57% ± 3%; P = 0.08). Both beef and milk ingestion were followed by an increase in the phosphorylation of mammalian target of rapamycin complex 1 and 70-kDa S6 protein kinase 1 during postexercise recovery. Milk ingestion increased myofibrillar protein synthesis rates to a greater extent than did beef ingestion during the 0- to 2-h postexercise phase (P = 0.013). However, the increase in myofibrillar protein synthesis rates did not differ between milk and beef ingestion during the entire 0- to 5-h postexercise phase (P = 0.114).


CONCLUSIONS
Both milk and beef ingestion augment the postexercise myofibrillar protein synthetic response in young men, with a stronger stimulation of myofibrillar protein synthesis during the early postprandial stage after milk ingestion. This trial was registered at www.clinicaltrials.gov as NCT01578590.
NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands.
Nicholas A
NA
Burd
NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands.
Stefan H
SH
Gorissen
NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands.
Stephan
S
van Vliet
NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands.
Tim
T
Snijders
NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, Netherlands l.vanloon@maastrichtuniversity.nl.
Luc Jc
LJ
van Loon
D000273:Adipose Tissue / Q000378:metabolism; D000601:Amino Acids, Essential / Q000097:blood; D000818:Animals; D015992:Body Mass Index; D001835:Body Weight; D002417:Cattle; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D002149:Energy Intake; D015444:Exercise; D006801:Humans; D008297:Male; D008892:Milk; D009124:Muscle Proteins / Q000378:metabolism; D019518:Postprandial Period; D000069466:Red Meat; D055815:Young Adult
D000601:Amino Acids, Essential; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D009124:Muscle Proteins
hypertrophy; leucine; muscle mass; sports nutrition; weightlifting