1, 2, 3, and 5 d)In vivoDietary royal jelly and pRJ (1% and 5% for 3 months)  In vitroSC isolated from aged miceIn vivo21-months old male C57BL/6 mice as a mouse model of sarcopenia  In vitroEG1: royal jelly treated SCEG2: pRJ treated SCCG: untreated SCIn vivoEG1 and EG2: aged mice on 1% and 5% royal jelly, respectivelyEG3 and EG4: aged mice on 1% and 5% pRJ, respectivelyCG: untreated aged mice  In vitroSC proliferation and differentiation into myotubes and AKT signaling.In vivoNo of SC, skeletal muscle weight, grip strength, regenerative capacity of injured muscle, and serum IGF-1.