Regional regulation of focal adhesion kinase after concentric and eccentric loading is related to remodelling of human skeletal muscle

摘要

Abstract Aims We assessed focal adhesion kinase ( FAK ) response to concentric ( CON ) vs eccentric ( ECC ) resistance training ( RT ) at two vastus lateralis ( VL ) sites, and the relationships between FAK , muscle protein synthesis ( MPS ) and morphological remodelling. Methods Six young males trained both legs unilaterally 3?times/week for 8?weeks; one leg performed CON RT , the contralateral performed ECC RT . Muscle biopsies were collected after training from VL mid‐belly ( MID ) and distal (distal) sites at 0, 4, 8?weeks. Focal adhesion kinase content and activation were evaluated by immunoblotting. MPS was assessed by deuterium oxide tracer; morphological adaptations were evaluated by ultrasound and DXA . Results pY 397‐ FAK 8?weeks levels were ~4‐fold greater after ECC at the distal site compared to CON ( P ??.05); pY 397 FAK to total FAK ratio was greater in ECC vs CON at 4 (~2.2‐fold, P ??.05) and 8?weeks (~9‐fold, P ??.001) at the distal site. Meta‐vinculin was found transiently increased at 4?weeks at the distal site only after ECC RT . ECC presented greater fascicle length (Lf) increases (10.5% vs 4%), whereas CON showed greater in pennation angle ( PA ) changes (12.3% vs 2.1%). MPS did not differ between exercise types or muscle sites at all time points. distal pY 397‐ FAK and pY 397‐ FAK / FAK values correlated to changes in Lf at 8?weeks ( r ?=?.76, P ??.01 and r ?=?.66, P ??.05 respectively). Conclusion Focal adhesion kinase phosphorylation was greater at 8?weeks after ECC RT and was muscle region‐specific. FAK activity correlated to contraction‐dependent architectural remodelling, suggesting a potential role of FAK in orienting muscle structural changes in response to distinct mechanical stimuli.