No Difference in Post-Workout Protein Synthesis Rates Following EAAs or Whey Protein in Women
A comparative study.
This study investigates the effects of different protein doses on post-exercise myofibrillar protein synthesis (MyoPS) rates in young females. The research aims to compare the MyoPS response following ingestion of 1.5 g essential amino acids (EAA), 15 g whey protein, and 20 g whey protein after resistance exercise.
PMID: 39880386
Key Points
Methods
The study included 28 healthy, recreationally active females (age: 28 ± 8 years; BMI: 24 ± 3 kg/m2).
Participants were randomly assigned to receive either 1.5 g EAA (n=10), 15 g whey protein (n=10), or 20 g whey protein (n=8) after completing a bout of unilateral resistance exercise.
L-[ring-2H5]-phenylalanine tracer was infused to assess MyoPS rates.
Blood and muscle samples were collected pre- and post-exercise and drink ingestion to measure MyoPS and gene expression.
Results
Plasma leucine concentrations increased more following 15 and 20 g whey protein than 1.5 g EAA (P < 0.0001).
Exercise and drink ingestion increased basal MyoPS rates in all groups:
0-2 hours post-exercise: 0.117 ± 0.028, 0.098 ± 0.051, and 0.116 ± 0.034%·h−1 for 1.5, 15, and 20 g drinks, respectively (P < 0.0001).
2-4 hours post-exercise: 0.110 ± 0.028, 0.074 ± 0.038, and 0.082 ± 0.061%·h−1 for 1.5, 15, and 20 g drinks, respectively (P = 0.008).
No significant differences in MyoPS rates were observed between the three drink conditions (P = 0.416).
Post-exercise changes in muscle mRNA expression of genes involved in protein turnover, substrate utilisation, remodelling, and inflammation did not differ between drinks (P > 0.050).
Related
Practical Takeaways
For young female lifters, consuming as little as 1.5 g of essential amino acids (containing 0.6 g leucine) may be sufficient to stimulate maximal post-exercise myofibrillar protein synthesis rates.
This finding suggests that lower protein doses than currently recommended (>20 g protein or ≥2 g leucine) may be adequate for optimising muscle protein synthesis in young females after resistance exercise.
Women may not need to consume large amounts of protein immediately after exercise to maximise muscle protein synthesis, which could benefit those managing calorie intake or struggling to meet high protein requirements.
Key Takeaways
Post-exercise myofibrillar protein synthesis rates in young females do not differ significantly following ingestion of 1.5 g EAA, 15 g whey protein, or 20 g whey protein.
As little as 0.6 g of leucine (contained in the 1.5 g EAA drink) may stimulate maximal post-exercise myofibrillar protein synthesis in young females.
Current protein recommendations based on male studies (>20 g protein or ≥2 g leucine) may be higher than necessary for young females to optimise post-exercise muscle protein synthesis.
These findings highlight the importance of considering sex-specific nutritional recommendations in sports and exercise nutrition.
Further research is needed to confirm these results and investigate the long-term effects of lower protein doses on muscle adaptation and hypertrophy in females.
Reference
Apicella MCA, Jameson TSO, Monteyne AJ, Pavis GF, Abdelrahman DR, Murton AJ, Alamdari N, Dirks ML, Wall BT, Stephens FB. Postexercise myofibrillar protein synthesis rates do not differ following 1.5 g essential amino acids compared with 15 and 20 g of whey protein in young females. Am J Physiol Endocrinol Metab. 2025 Mar 1;328(3):E420-E434. doi: 10.1152/ajpendo.00365.2024. Epub 2025 Jan 29. PMID: 39880386.