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Louise M. Burke, Julie A Winter, David Cameron-Smith, Marc Enslen, Michelle Farnfield, and Jacques Decombaz

The authors undertook 2 crossover-designed studies to characterize plasma amino acid (AA) responses to the intake of 20 g of protein. In Study 1, 15 untrained and overnight-fasted subjects consumed 20 g protein from skim milk, soy milk, beefsteak, boiled egg, and a liquid meal supplement. In Study 2, 10 fasted endurance-trained subjects consumed 20 g protein from a protein-rich sports bar at rest and after a 60-min submaximal ride. Plasma AA concentrations were measured immediately before and for 180 min after food ingestion using a gas-chromatography flame-ionization detection technique. A pharmacokinetic analysis was undertaken for profiles of total AAs (TAA), essential AAs, branched-chain AAs (BCAA), and leucine. Although area-under-the-curve values for plasma TAA were similar across protein sources, the pattern of aminoacidemia showed robust differences between foods, with liquid forms of protein achieving peak concentrations twice as quickly after ingestion as solid protein-rich foods (e.g., ~50 min vs ~100 min) and skim milk achieving a significantly faster peak leucine concentration than all other foods (~25 min). Completing exercise before ingesting protein sources did not cause statistically significant changes in the pattern of delivery of key AAs, BCAAs, and leucine apart from a 20–40% increase in the rate of elimination. These results may be useful to plan the type and timing of intake of protein-rich foods to maximize the protein synthetic response to various stimuli such as exercise.

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Krissy D. Weisgarber, Darren G. Candow, and Emelie S. M. Vogt

Purpose:

To determine the effects of whey protein before and during resistance exercise (RE) on body composition and strength in young adults.

Methods:

Participants were randomized to ingest whey protein (PRO; 0.3 g/kg protein; n = 9, 24.58 ± 1.8 yr, 88.3 ± 17.1 kg, 172.5 ± 8.0 cm) or placebo (PLA; 0.2 g/kg cornstarch maltodextrin + 0.1 g/kg sucrose; n = 8, 23.6 ± 4.4 yr, 82.6 ± 16.1 kg, 169.4 ± 9.2 cm) during RE (3 sets of 6–10 repetitions for 9 whole-body exercises), which was performed 4 d/wk for 8 wk. PRO and PLA were mixed with water (600 ml); 50% of the solution containing 0.15 g/kg of PRO or PLA was consumed immediately before the start of exercise, and ~1.9% of the remaining solution containing ~0.006 g/kg of PRO or PLA was consumed immediately after each training set. Before and after the study, measures were taken for leantissue mass (dual-energy X-ray absorptiometry), muscle size of the elbow and knee flexors and extensors and ankle dorsiflexors and plantar flexors (ultrasound), and muscle strength (1-repetition-maximum chest press).

Results:

There was a significant increase (p < .05) in muscle size of the knee extensors (PRO 0.6 ± 0.4 cm, PLA 0.1 ± 0.5 cm), knee flexors (PRO 0.4 ± 0.6 cm, PLA 0.5 ± 0.7 cm) and ankle plantar flexors (PRO 0.6 ± 0.7 cm, PLA 0.8 ± 1.4 cm) and chest-press strength (PRO 16.6 ± 11.1 kg, PLA 9.1 ± 14.6 kg) over time, with no differences between groups.

Conclusion:

The ingestion of whey protein immediately before the start of exercise and again after each training set has no effect on muscle mass and strength in untrained young adults.

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Mark Messina, Heidi Lynch, Jared M. Dickinson, and Katharine E. Reed

; Wilkinson et al., 2013 ). Although acute studies evaluating MPS may provide valuable insight, MPS following protein supplementation and resistance exercise may last for at least 24 hr ( Burd et al., 2011 ). Thus, it is important to determine how protein source affects changes in strength and lean tissue

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Ben Desbrow, Joanna McCormack, Louise M. Burke, Gregory R. Cox, Kieran Fallon, Matthew Hislop, Ruth Logan, Nello Marino, Susan M. Sawyer, Greg Shaw, Anita Star, Helen Vidgen, and Michael Leveritt

It is the position of Sports Dietitians Australia (SDA) that adolescent athletes have unique nutritional requirements as a consequence of undertaking daily training and competition in addition to the demands of growth and development. As such, SDA established an expert multidisciplinary panel to undertake an independent review of the relevant scientific evidence and consulted with its professional members to develop sports nutrition recommendations for active and competitive adolescent athletes. The position of SDA is that dietary education and recommendations for these adolescent athletes should reinforce eating for long term health. More specifically, the adolescent athlete should be encouraged to moderate eating patterns to reflect daily exercise demands and provide a regular spread of high quality carbohydrate and protein sources over the day, especially in the period immediately after training. SDA recommends that consideration also be given to the dietary calcium, Vitamin D and iron intake of adolescent athletes due to the elevated risk of deficiency of these nutrients. To maintain optimal hydration, adolescent athletes should have access to fluids that are clean, cool and supplied in sufficient quantities before, during and after participation in sport. Finally, it is the position of SDA that nutrient needs should be met by core foods rather than supplements, as the recommendation of dietary supplements to developing athletes over-emphasizes their ability to manipulate performance in comparison with other training and dietary strategies.

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Fernando Naclerio, Marcos Seijo, Eneko Larumbe-Zabala, and Conrad P. Earnest

Beef powder is a new high-quality protein source scarcely researched relative to exercise performance. The present study examined the impact of ingesting hydrolyzed beef protein, whey protein, and carbohydrate on strength performance (1RM), body composition (via plethysmography), limb circumferences and muscular thickness (via ultrasonography), following an 8-week resistance-training program. After being randomly assigned to one of the following groups: Beef, Whey, or Carbohydrate, twenty four recreationally physically active males (n = 8 per treatment) ingested 20 g of supplement, mixed with orange juice, once a day (immediately after workout or before breakfast). Post intervention changes were examined as percent change and 95% CIs. Beef (2.0%, CI, 0.2–2.38%) and Whey (1.4%, CI, 0.2–2.6%) but not Carbohydrate (0.0%, CI, -1.2–1.2%) increased fat-free mass. All groups increased vastus medialis thickness: Beef (11.1%, CI, 6.3–15.9%), Whey (12.1%, CI, 4.0, -20.2%), Carbohydrate (6.3%, CI, 1.9–10.6%). Beef (11.2%, CI, 5.9–16.5%) and Carbohydrate (4.5%, CI, 1.6–7.4%), but not Whey (1.1%, CI, -1.7–4.0%), increased biceps brachialis thickness, while only Beef increased arm (4.8%, CI, 2.3–7.3%) and thigh (11.2%, 95%CI 0.4–5.9%) circumferences. Although the three groups significantly improved 1RM Squat (Beef 21.6%, CI 5.5–37.7%; Whey 14.6%, CI, 5.9–23.3%; Carbohydrate 19.6%, CI, 2.2–37.1%), for the 1RM bench press the improvements were significant for Beef (15.8% CI 7.0–24.7%) and Whey (5.8%, CI, 1.7–9.8%) but not for carbohydrate (11.4%, CI, -0.9-23.6%). Protein-carbohydrate supplementation supports fat-free mass accretion and lower body hypertrophy. Hydrolyzed beef promotes upper body hypertrophy along with similar performance outcomes as observed when supplementing with whey isolate or maltodextrin.

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. Kordick * Shane McFarland * Denver Lancaster * Kristine Clark * Mary P. Miles * 12 2012 22 22 6 6 444 444 451 451 10.1123/ijsnem.22.6.444 Effect of Intake of Different Dietary Protein Sources on Plasma Amino Acid Profiles at Rest and after Exercise Louise M. Burke * Julie A Winter * David

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Rebekah D. Alcock, Gregory C. Shaw, Nicolin Tee, Marijke Welvaert, and Louise M. Burke

, and Consumption The current study was carried out during part of a larger research project investigating plasma amino acid availability after the consumption of various protein sources ( Alcock et al., 2018 ). For the current study, data were collected after the consumption of four different protein

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Julien Louis, Fabrice Vercruyssen, Olivier Dupuy, and Thierry Bernard

). It is thus recommended to practitioners or coaches working with master athletes to prepare examples of meals and snacks containing good-quality protein sources. The best protein sources to promote muscle protein synthesis are those containing essential amino acids and leucine, in particular. Leucine

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Oliver C. Witard, Ina Garthe, and Stuart M. Phillips

. Carbohydrate-rich foods should be added to meet the individual daily energy needs. BM = body mass. In terms of protein type, leucine-rich rapidly digested protein sources, such as whey protein, have been shown to elicit a greater stimulation of MPS during training recovery compared with slowly digested

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Joel L. Prowting, Debra Bemben, Christopher D. Black, Eric A. Day, and Jason A. Campbell

likely that any physiological effect exerted by the CP would have occurred within these intramuscular connective tissues (such as the ECM). It must be noted that nonessential collagenous amino acids (i.e., glycine, proline) are present to differing degrees within complete, high-quality protein sources