Differential Stimulation of Post-Exercise Myofibrillar Protein Synthesis in Humans Following Isonitrogenous, Isocaloric Pre-Exercise Feeding

Abstract

The aim of this study was to test the effects of two disparate isonitrogenous, isocaloric pre-exercise feeds on deuterium-oxide (D2O) derived measures of myofibrillar protein synthesis (myoPS) in humans. Methods: In a double-blind parallel group design, 22 resistance-trained men aged 18 to 35 years ingested a meal (6 kcal·kg−1, 0.8 g·kg−1 carbohydrate, 0.2 g·kg−1 fat) with 0.33 g·kg−1 nonessential amino acids blend (NEAA) or whey protein (WHEY), prior to resistance exercise (70% 1RM back-squats, 10 reps per set to failure, 25% duty cycle). Biopsies of M. vastus lateralis were obtained pre-ingestion (PRE) and +3 h post-exercise (POST). The myofibrillar fractional synthetic rate (myoFSR) was calculated via deuterium labelling of myofibrillar-bound alanine, measured by gas chromatography–pyrolysis–isotope ratio mass spectrometry (GC-Pyr-IRMS). Data are a mean percentage change (95% CI). Results: There was no discernable change in myoFSR following NEAA (10(−5, 25) %, p = 0.235), whereas an increase in myoFSR was observed after WHEY (28 (13, 43) %, p = 0.003). Conclusions: Measured by a D2O tracer technique, a disparate myoPS response was observed between NEAA and WHEY. Pre-exercise ingestion of whey protein increased post-exercise myoPS, whereas a NEAA blend did not, supporting the use of NEAA as a viable isonitrogenous negative control.

The Effect of Whey Protein Supplementation on Myofibrillar Protein Synthesis and Performance Recovery in Resistance-Trained Men

“…In a recent study, using the D 2 O-method, we reported that acute ingestion of 0.33 g•kg −1 of whey protein increased postexercise myoFSR,~30 % for~5 h, in a young healthy resistance-trained cohort [7]. In the present study, the D 2 O-tracer technique was employed to measure myoFSR, but this time measuring the effect of 0.33 g•kg −1 •d −1 of supplemental whey protein over multiple days of RT.…”

“…In order to maximise postexercise/postprandial myoPS and ensure compliance to the study diet, morning ingestion of 0.33 g•kg −1 •d −1 of protein, from a whey protein concentrate supplement [20], after an overnight fast (~10 h postabsorptive, ~0.5 pre-exercise [21]), was conducted. The control group consumed an isonitrogenous formulation of nonessential amino acids that does not stimulate myoPS (Carbery Food Ingredients, Ireland) (Appendix C) [7]. Supplements were mixed with 500 ml water, identically flavoured (vanilla) and administered in a double-blind fashion.…”

Anabolic response to essential amino acid plus whey protein composition is greater than whey protein alone in young healthy adults

“…Non-essential amino acids (NEAA) are not required for the acute anabolic response to EAA consumption [2][3][4]. This is because NEAA are normally produced in the body at fast enough rates to avoid deficiencies.…”

“…EAA cannot be produced in the body, but are primarily responsible for the stimulation of muscle protein synthesis [1]. Non-essential amino acid consumption, with or without concomitant EAA consumption, fails to affect protein synthesis in healthy, well-nourished volunteers, whether at rest [1,2] or after exercise [3,4]. The response of muscle protein synthesis following ingestion of a composition of free EAA is more than twice the response to consumption of a comparable dosage (g/g) of whey protein isolate [5].…”

Casein Protein Hydrolysate Fed Human Serum From Older Adults Regulates In Vitro Muscle Protein Synthesis, Muscle Protein Breakdown and Myotube Growth

“…While elevated levels of EAA strongly increase anabolic signalling and MPS [8,25], NEAA do not have a stimulatory effect on MPS in vitro [17] or in vivo [6,26,27]. It has been demonstrated that significant stimulation of MPS requires at least a two-fold increase of plasma aminoacidemia above basal levels [28].…”