Background Sarcopenia can be an aging\induced deterioration of skeletal muscle mass and function. given to mice.18 In VIB group, mice were given LMHFV treatment (35 Hz, 0.3 g, 20 min/day, 5 days/week) according to our previous protocol.8 In COM group, both LMHFV and HMB supplement were provided accordingly. The mice in CTL group were put on vibration platform with power off to receive sham treatment with the same regime. All of the mice were euthanized at specified time points for the following assessments. The research protocol was Tangeretin (Tangeritin) approved by the Animal Experimentation Ethics Committee of the Chinese University of Hong Kong (Ref: 15\200\MIS). At endpoints, body mass of mice was measured before euthanasia.8, 17 Gastrocnemii of right hind limbs were carefully isolated with the Achilles tendon and femur condylar attached, which was then put in the tissue bath of mammalian Ringer solution for functional test. The contralateral muscle was also harvested after weighing, snap frozen with 2\methylbutane in optimal length for 20 s, and stored at ?80C for histological and immunofluorescence examination. Serum samples were collected and stored at ?80C for myostatin and adiponectin quantification by enzyme\linked immunosorbent assay (R&D Systems, Minneapolis, MN, USA) as previously reported.8 Grip strength measurement Forelimb grip strength of mice was measured with a force gauge (Mark\10 Corporation, NY, USA). Mice held by the tail grasped the grid connected to the pressure gauge with their fore paws. The tails of mice were pulled slowly until the mice released their fore paws from the grid.19, 20 The peak force of each test was recorded; three repeats were collected and averaged. Dual\energy X\ray absorptiometry analysis Measurement of whole\body composition was performed using dual\energy X\ray absorptiometry (DXA) (UltraFocus DXA, Faxitron, AZ, USA) at HES7 specified time points before euthanasia. Under general anaesthesia, mice were placed in the DXA device in prone position with four limbs fixed for scanning. Percentage lean/excess fat mass were analysed using default BiopticsVision software. functional test Tangeretin (Tangeritin) muscle functional test was conducted according to our established protocols using muscle functional test system (800A, Aurora Scientific Inc., Newmarket, Canada).8, 17, 21 After 15 min stabilization, the muscle was activated by two tetanic contractions (1A, 300 ms, 150 Hz) with 5 min interval. The optimal length (L0) of the muscle was determined by continuous stimulations with increasing muscle length until the new response value was equal to the former one. Twitch pressure (F0) output was measured at the optimal length. Muscle was stimulated by one electronic stimulus with 1 min interval and the response was defined as F0. Three twitch responses were measured and averaged as the isometric F0. The tetanic pressure (Ft) was detected by stimulation at 80 Hz Tangeretin (Tangeritin) for 300 ms. Three tetanic responses were measured at 5 min intervals and averaged as the Ft. After the measurements, the gastrocnemius was dried and weighted. The gastrocnemius from the other leg was also isolated and weighted. Muscle mass was the average of both legs. Muscle cross\sectional area, specific twitch pressure (SF0), and specific tetanic pressure (SFt) were calculated as previously described.22 Micro\computed tomography Micro\computed tomography was performed at the distal side of femur harvested from SAMP8 mice (vivaCT, Scanco Medical, Brttisellen, Switzerland) based on our protocol.21 Images were acquired Tangeretin (Tangeritin) at 70 kVp and 114 mA, and the region of interest covered 30 slides from the end of growth plates to Tangeretin (Tangeritin) the proximal direction. Tissues within the threshold range of 220C1000 were segmented, reconstructed, and evaluated for the volume of mineralized bone. Histological and immunofluorescence.