Adaptations to exercise training are determined by the response of metabolic and molecular mechanisms that determine changes in proteins. The type, intensity, and duration of exercise, as well as nutrition, determine these responses. The importance of protein, in the form of intact proteins, hydrolysates, or free amino acids, for exercise adaptations is widely recognized. Exercise along with protein intake results in accumulation of proteins that influence training adaptations. The total amount of protein necessary to optimize adaptations is less important than the type of protein, timing of protein intake, and the other nutrients ingested concurrently with the protein. Acute metabolic studies offer an important tool to study the responses of protein balance to various exercise and nutritional interventions. Recent studies suggest that ingestion of free amino acids plus carbohydrates before exercise results in a superior anabolic response to exercise than if ingested after exercise. However, the difference between pre- and post exercise ingestion of intact proteins is not apparent. Thus, the anabolic response to exercise plus protein ingestion seems to be determined by the interaction of timing of nutrient intake in relation to exercise and the nutrients ingested. More research is necessary to delineate the optimal combination of nutrients and timing for various types of training adaptations. Protein and amino acid intake have long been deemed important for athletes and exercising individuals. Olympic athletes, from the legendary Milo to many in the 1936 Berlin games, reportedly consumed large amounts of protein. Modern athletes may consume slightly less than these historical figures, yet protein is deemed extremely important by most. Protein is important as a source of amino acids for recovery from exercise and repair of damaged tissues, as well as for adaptations to exercise training, such as muscle hypertrophy and mitochondrial biogenesis.
Kevin D. Tipton
Elisabet Børsheim, Asle Aarsland and Robert R. Wolfe
This study tests the hypotheses that (a) a mixture of whey protein, amino acids (AA), and carbohydrates (CHO) stimulates net muscle protein synthesis to a greater extent than isoenergetic CHO alone after resistance exercise; and (b) that the stimulatory effect of a protein, AA, and CHO mixture will last beyond the 1 st hour after intake. Eight subjects participated in 2 trials. In one (PAAC), they ingested 77.4 g CHO, 17.5 g whey protein, and 4.9 g AA 1 hr after resistance exercise. In the other (CON), 100 g CHO was ingested instead. They received a primed constant infusion of L-[2H5]-phenylalanine, and samples from femoral artery and vein, and biopsies from vastus lateralis were obtained. The area under the curve for net uptake of phenylalanine into muscle above pre-drink value was 128 ±42 mg • leg-1 (PAAC) versus 32 ± 10 mg - leg-1 (CON) for the 3 hr after the drink (p = .04). The net protein balance response to the mixture consisted of two components, one rapid immediate response, and a smaller delayed response about 90 min after drink, whereas in CON only a small delayed response was seen. We conclude that after resistance exercise, a mixture of whey protein, AA, and CHO stimulated muscle protein synthesis to a greater extent than isoenergetic CHO alone. Further, compared to previously reported findings, the addition of protein to an AA + CHO mixture seems to extend the anabolic effect.
Ulrika Andersson-Hall, Stefan Pettersson, Fredrik Edin, Anders Pedersen, Daniel Malmodin and Klavs Madsen
current set-up has advantages such as protective effects for the immune system and sustained net muscle protein synthesis is yet to be determined. Acknowledgments We thank Janni Mosgaard Jensen and Gitte Kaiser Hartvigsen, Dept. of Public Health, Aarhus University, for their excellent technical assistance
Vandre C. Figueiredo, Michelle M. Farnfield, Megan L.R. Ross, Petra Gran, Shona L. Halson, Jonathan M. Peake, David Cameron-Smith and James F. Markworth
provided by Dr. Andrew Garnham School of Exercise and Nutrition Sciences, Deakin University. References Borsheim , E. , Cree , M.G. , Tipton , K.D. , Elliott , T.A. , Aarsland , A. , & Wolfe , R.R. ( 2004 ). Effect of carbohydrate intake on net muscle protein synthesis during recovery from
Sherry Robertson and Margo Mountjoy
Orthopaedic & Sports Physical Therapy, 41 , 60 – 69 . PubMed ID: 21212503 doi:10.2519/jospt.2011.3312 10.2519/jospt.2011.3312 Tipton , K.D. , Elliott , T.A. , Cree , M.G. , Aarsland , A.A. , Sanford , A.P. , & Wolfe , R.R. ( 2007 ). Stimulation of net muscle protein synthesis by whey protein