Essential amino acid-enriched whey enhances post-exercise whole-body protein balance during energy deficit more than iso-nitrogenous whey or a mixed-macronutrient meal: a randomized, crossover study

Abstract

Background: The effects of ingesting varying essential amino acid (EAA)/protein-containing food formats on protein kinetics during energy deficit are undetermined. Therefore, recommendations for EAA/protein food formats necessary to optimize both whole-body protein balance and muscle protein synthesis (MPS) during energy deficit are unknown. We measured protein kinetics after consuming iso-nitrogenous amounts of free-form essential amino acid-enriched whey (EAA + W; 34.7 g protein, 24 g EAA sourced from whey and free-form EAA), whey (WHEY; 34.7 g protein, 18.7 g EAA), or a mixed-macronutrient meal (MEAL; 34.7 g protein, 11.4 g EAA) after exercise during short-term energy deficit.

Methods: Ten adults (mean ± SD; 21 ± 4 y; 25.7 ± 1.7 kg/m2) completed a randomized, double-blind crossover study consisting of three, 5 d energy-deficit periods (- 30 ± 3% of total energy requirements), separated by 14 d. Whole-body protein synthesis (PS), breakdown (PB), and net balance (NET) were determined at rest and in response to combination exercise consisting of load carriage treadmill walking, deadlifts, and box step-ups at the end of each energy deficit using L-[2H5]-phenylalanine and L-[2H2]-tyrosine infusions. Treatments were ingested immediately post-exercise. Mixed-muscle protein synthesis (mixed-MPS) was measured during exercise through recovery.

Results: Change (Δ postabsorptive + exercise to postprandial + recovery [mean treatment difference (95%CI)]) in whole-body (g/180 min) PS was 15.8 (9.8, 21.9; P = 0.001) and 19.4 (14.8, 24.0; P = 0.001) greater for EAA + W than WHEY and MEAL, respectively, with no difference between WHEY and MEAL. ΔPB was - 6.3 (- 11.5, - 1.18; P = 0.02) greater for EAA + W than WHEY and - 7.7 (- 11.9, - 3.6; P = 0.002) greater for MEAL than WHEY, with no difference between EAA + W and MEAL. ΔNET was 22.1 (20.5, 23.8; P = 0.001) and 18.0 (16.5, 19.5; P = 0.00) greater for EAA + W than WHEY and MEAL, respectively, while ΔNET was 4.2 (2.7, 5.6; P = 0.001) greater for MEAL than WHEY. Mixed-MPS did not differ between treatments.

Conclusions: While mixed-MPS was similar across treatments, combining free-form EAA with whey promotes greater whole-body net protein balance during energy deficit compared to iso-nitrogenous amounts of whey or a mixed-macronutrient meal.

Trial registration: ClinicalTrials.gov, Identifier no. NCT04004715 . Retrospectively registered 28 June 2019, first enrollment 6 June 2019.

Keywords: And energy restriction; Free-form amino acids; Muscle protein synthesis; Whole-body protein turnover.

Conflict of interest statement

JAG, DDC, AHM, JTA, MAW, ANV, CTC, NEM, LMM, JWC, AAF, and SMP have no conflicts of interest associated with this research. RRW is an inventor of patent entitled “Composition for Stimulating Muscle Growth, Repair, and Maintenance,” US Patent (16; 382,984). RRW is a shareholder in Essential Blends, LLC, and The Amino Company, LLC. RRW was not involved in data collection or analyses and was blinded to all data until final consolidation into manuscript form by JAG and SMP.

Figures

Fig. 1

Volunteer enrollment and retention

Fig. 2

Schematic of the infusion studies. Muscle biopsy and blood samples were used in combination with primed, constant infusions of L-[2H5]-phenylalanine and L-[2H2]-tyrosine to determine the effects of EAA + W, WHEY, or MEAL ingestion on whole-body protein turnover following whole-body exercise as well as mixed muscle protein synthesis throughout an exercise and recovery period during energy deficit

Fig. 3

Mean ± SD (n = 10). Stable-isotope enrichments during the infusion studies

Fig. 4

a: Mean ± SD (n = 10). Postabsorptive plus exercise and postprandial post-exercise recovery whole-body protein synthesis after WHEY, EAA + W, and MEAL intake during energy deficit. *indicates post hoc difference between postabsorptive and postprandial within the same treatment (P = 0.001) and different lowercase letters indicate post hoc difference between treatments within the same condition (both, P < 0.01). b: Mean ± SD (n = 10). Postabsorptive plus exercise and postprandial post-exercise recovery whole-body protein breakdown after WHEY, EAA + W, and MEAL intake during energy deficit. *indicates post hoc difference between postabsorptive and postprandial within the same treatment (P = 0.011) and different lowercase letters indicate post hoc difference between treatments within the same condition (both, P = 0.001). c: Mean ± SD (n = 10). Postabsorptive plus exercise and postprandial post-exercise recovery whole-body net balance after WHEY, EAA + W, and MEAL intake during energy deficit. *indicates post hoc difference between postabsorptive and postprandial within the same treatment (P = 0.001) and different lowercase letters indicate post hoc difference between treatments within the same condition (both, P = 0.001). d: Mean ± SD (n = 10). Change in postabsorptive plus exercise and postprandial post-exercise recovery whole-body protein turnover after WHEY, EAA + W, and MEAL intake during energy deficit. Different lowercase letters indicate difference between treatments within the protein synthesis, protein breakdown, and net balance measures (all, P < 0.05). e: Change in postabsorptive plus exercise and postprandial post-exercise recovery whole-body protein synthesis relative to EAA intake after WHEY, EAA + W, and MEAL intake during energy deficit. Different lowercase letters indicate difference between treatments (all, P < 0.05). f: Mean ± SD (n = 10). Postabsorptive plus exercise and postprandial post-exercise recovery phenylalanine hydroxylation after WHEY, EAA + W, and MEAL intake during energy deficit. *indicates post hoc difference between postabsorptive and postprandial within the same treatment (P = 0.001) and different lowercase letters indicate post hoc difference between treatments within the same condition (both, P = 0.001)

Fig. 5

a Mean ± SD (n = 10). Mixed-muscle protein synthesis responses to whole-body exercise plus post exercise recovery feeding with WHEY, EAA + W, and MEAL intake during energy deficit. No difference between treatments (P = 0.68). b Mean ± SD (n = 10). Relative mixed-muscle protein synthesis responses, expressed relative to study treatment energy, to whole-body exercise plus post exercise recovery feeding with WHEY, EAA + W, and MEAL intake during energy deficit. Different lowercase letters indicate difference between treatment (both, P < 0.05)

Fig. 6

a Mean ± SD (n = 10). Plasma essential amino acid concentrations after WHEY, EAA + W, and MEAL intake during energy deficit. Different symbols indicate post hoc difference (all, P < 0.05) between treatments within a time point. Different lowercase letters indicate post hoc difference between time points within a treatment (all, P < 0.05). b Plasma leucine concentrations after WHEY, EAA + W, and MEAL intake during energy deficit. Different symbols indicate post hoc difference (all, P < 0.02) between treatments within a time point. Different lowercase letters indicate post hoc difference between time points within a treatment (P < 0.03). c Plasma phenylalanine concentrations after WHEY, EAA + W, and MEAL intake during energy deficit. Different symbols indicate post hoc difference (all, P < 0.02) between treatments within a time point. Different lowercase letters indicate post hoc difference between time points within a treatment (P < 0.05). d Plasma tyrosine concentrations after WHEY, EAA + W, and MEAL intake during energy deficit. Different symbols indicate post hoc difference (all, P < 0.04) between treatments within a time point. Different lowercase letters indicate post hoc difference between time points within a treatment (P < 0.03). e Mean ± SD (n = 10). Plasma insulin concentrations after WHEY, EAA + W, and MEAL intake during energy deficit. Different symbols indicate difference between treatment independent of time point (P = 0.04). Different lowercase letters indicate difference between time points independent of treatment (P < 0.01)