Fish oil supplementation suppresses resistance exercise and feeding‐induced increases in anabolic signaling without affecting myofibrillar protein synthesis in young men

Chris McGlory, Sophie L. Wardle, Lindsay S. Macnaughton, Oliver C. Witard, Fraser Scott, James Dick, J. Gordon Bell, Stuart M. Phillips, Stuart D. R. Galloway, D. Lee Hamilton, Kevin D. Tipton

Fish oil (FO) supplementation potentiates muscle protein synthesis (MPS) in response to a hyperaminoacidemic-hyperinsulinemic infusion. WhetherFOsupplementation potentiatesMPSin response to protein ingestion or when protein ingestion is combined with resistance exercise (RE) remains unknown. In a randomized, parallel group design, 20 healthy males were randomized to receive 5 g/day of eitherFOor coconut oil control (CO) for 8 weeks. After supplementation, participants performed a bout of unilateralREfollowed by ingestion of 30 g of whey protein. Skeletal muscle biopsies were obtained before and after supplementation for assessment of muscle lipid composition and relevant protein kinase activities. Infusion ofl-[ring-(13)C6] phenylalanine was used to measure basal myofibrillarMPSat rest (REST), in a nonexercised leg following protein ingestion (FED) and followingREand protein ingestion (FEDEX).MPSwas significantly elevated aboveRESTduringFEDEXin both theFOandCOgroups, but there was no effect of supplementation. There was a significant increase inMPSin both groups aboveRESTduringFEDbut no effect of supplementation. Supplementation significantly decreased panPKBactivity atRESTin theFOgroup but not theCOgroup. There was a significant increase fromRESTat post-REforPKBandAMPKα2 activity in theCOgroup but not in theFOgroup. InFEDEX, there was a significant increase in p70S6K1 activity fromRESTat 3 h in theCOgroup only. These data highlight that 8 weeks ofFOsupplementation alters kinase signaling activity in response toREplus protein ingestion without influencingMPS.