Low-load resistance training during step-reduction attenuates declines in muscle mass and strength and enhances anabolic sensitivity in older XXXX .

@entity7792 @entity1 @entity8959 @entity842 @entity2057 @entity7047 @entity369
Step-reduction (SR) in older adults results in @entity2057 and an attenuated rise in postprandial muscle protein synthesis (MPS): anabolic resistance. Knowing that @entity7047 ( @entity7047 ) can enhance MPS, we examined whether @entity7047 could enhance MPS following 2  weeks of SR. In addition, as we postulated that SR may impair feeding-induced vasodilation limiting nutrient delivery to muscle, we also examined whether @entity7792 ( @entity7792 ), as an @entity369 and @entity842 precursor, could attenuate muscle anabolic resistance accompanying SR. We used a unilateral leg model to compare older subjects' who had undergone SR to a loaded condition of SR plus @entity7047 (SR  +  @entity7047 ). Thirty older @entity1 (70      1  years) underwent 14  days of SR (<1500  steps/day) with supplementation of either 5  g/day @entity7792 or @entity8959 placebo. Throughout SR, subjects performed unilateral low-load @entity7047 thrice weekly. We assessed muscle protein synthesis in the postabsorptive and postprandial state (20  g whey isolate plus 15  g @entity8959 or as micellar-whey with 5  g @entity7792 or 15  g @entity8959 , n  =  10/group). As MPS was similar after ingestion of either whey isolate, micellar-whey, or micellar-whey  +  @entity7792 data related to different dietary groups were collapsed to compare SR and SR  +  @entity7047 legs. Subjects' daily steps were reduced by 80      2% during SR (P  <  0.001) compared with baseline. Leg fat-free mass decreased with SR (-124      61  g) and increased in the SR  +  @entity7047 (+126      68  g; P  =  0.003). Myofibrillar FSR was lower (P  <  0.0001) in the SR as compared with the SR  +  @entity7047 leg in the postabsorptive (0.026      0.001%/h vs. 0.045      0.001%/h) and postprandial states (0.055      0.002%/h vs. 0.115      0.003%/h). We conclude that low-load @entity7047 , but not supplementation with @entity7792 , can attenuate the deleterious effects of SR in aging muscle.
