Reducing NF-κB signalling nutritionally is associated with expedited recovery of skeletal muscle function after damage.

CONTEXT The early events regulating the remodelling programme following skeletal muscle damage are poorly understood. OBJECTIVE The objective of this study was to determine the association between myofibrillar protein synthesis (myoPS) and nuclear factor-kappa B (NF-κB) signalling by nutritionally accelerating recovery of muscle function following damage. DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS Healthy males and females consumed daily post-exercise and pre-bed protein-polyphenol (PP; n=9; 4 females) or isocaloric maltodextrin placebo (PLA; n=9; 3 females) drinks (parallel design), 6 days before and 3 days after 300 unilateral eccentric quadriceps contractions (EC) during complete dietary control. MAIN OUTCOME MEASURES Muscle function was assessed daily, and skeletal muscle biopsies were taken after 24, 27 and 36 h for measurements of myoPS rates using deuterated water, and gene ontology and NF-κB signalling analysis using an RT-qPCR gene array. RESULTS EC impaired muscle function for 48 h in PLA, but for just 24 h in PP (P=0.047). EC increased myoPS compared to the control leg during post-exercise (24-27 h; 0.14±0.01 vs 0.11±0.01%·h -1, respectively; P=0.075) and overnight periods (27-36 h; 0.10±0.01 vs 0.07±0.01%·h -1, respectively; P=0.020), but was not further increased by PP (P>0.05). PP decreased post-exercise and overnight muscle IL1R1 (PLA=2.8±0.4, PP=1.1±0.4 and PLA=1.9±0.4, PP=0.3±0.4 log2 fold change, respectively) and IL1RL1 (PLA=4.9±0.7, PP=1.6±0.8 and PLA=3.7±0.6, PP=0.7±0.7 log2 fold change, respectively) mRNA expression (P<0.05) and downstream NF-κB signalling compared to PLA. CONCLUSION PP ingestion likely accelerates recovery of muscle function by attenuating inflammatory NF-κB transcriptional signalling, possibly to reduce aberrant tissue degradation rather than increase myoPS rates.