Effect of High-Protein Diets on Integrated Myofibrillar Protein Synthesis before Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Pilot Study

Increasing dietary protein intake during periods of muscle disuse may mitigate the resulting decline in muscle protein synthesis (MPS). The purpose of this randomized pilot study was to determine the effect of increased protein intake during periods of disuse before anterior cruciate ligament (ACL) reconstruction on myofibrillar protein synthesis (MyoPS), and proteolytic and myogenic gene expression. Six healthy, young males (30 +/- 9 y) were randomized to consume a high-quality, optimal protein diet (OP; 1.9 g center dot kg(-1)center dot d(-1)) or adequate protein diet (AP; 1.2 g center dot kg(-1)center dot d(-1)) for two weeks before ACL reconstruction. Muscle biopsies collected during surgery were used to measure integrated MyoPS during the intervention (via daily deuterium oxide ingestion) and gene expression at the time of surgery. MyoPS tended to be higher, with a large effect size in OP compared to AP (0.71 +/- 0.1 and 0.54 +/- 0.1%center dot d(-1); p = 0.076; g = 1.56). Markers of proteolysis and myogenesis were not different between groups (p > 0.05); however, participants with greater MyoPS exhibited lower levels of MuRF1 gene expression compared to those with lower MyoPS (r = -0.82, p = 0.047). The data from this pilot study reveal a potential stimulatory effect of increased daily protein intake on MyoPS during injury-mediated disuse conditions that warrants further investigation.

Automated summary

This pilot study examines the effect of increased protein intake on myofibrillar protein synthesis and gene expression before ACL reconstruction. The results suggest that increased protein intake may enhance myofibrillar protein synthesis, but does not significantly affect proteolytic and myogenic gene expression.