HMB attenuates muscle loss during sustained energy deficit induced by calorie restriction and endurance exercise |
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Authors: | Bong-Sup Park Paul C Henning Samuel C Grant Won Jun Lee Sang-Rok Lee Bahram H Arjmandi Jeong-Su Kim |
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Institution: | 1. Department of Nutrition, Food, and Exercise Sciences, College of Human Sciences, The Florida State University, Tallahassee, FL, USA;2. The National High Magnetic Field Laboratory & Department of Chemical & Biomedical Engineering, The Florida State University, Tallahassee, FL, USA;3. Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, MA, USA;4. Department of Exercise Sciences, Ewha Womans University, Seoul, South Korea |
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Abstract: | ObjectiveTo investigate the efficacy and underlying mechanisms of β-hydroxy-β-methylbutyrate (HMB) on body composition, muscle mass and physical performance under catabolic versus normal training conditions.Materials/MethodsMice were divided into four groups (n = 10/group): 1) ALT = ad libitum + trained (1 h/d for 3 d/wk); 2) ALTH = ALT + HMB (0.5 g/kg BW/d); 3) C = calorie restricted (? 30%) + trained (6 h/d, 6 d/wk); and 4) CH = C + HMB. Repeated in vivo assessments included body composition, grip strength and sensorimotor coordination before and after the experimental protocol, while in vitro analyses included muscle wet weights, expression of selected genes and proteins regulating muscle mass, and myofiber cross-sectional area. ANOVAs were used with significance set at p < 0.05.ResultsALTH had greater lean mass than ALT and sensorimotor function increased in ALTH, but decreased in ALT under normal training conditions. Grip strength decreased only in C, but was maintained in CH. Gastrocnemius mass and myofiber CSA were greater in CH than C following catabolic conditions. Gastrocnemius atrogin-1 mRNA expression was elevated in C but not in CH compared to all other groups whereas atrogin-1 protein levels showed no significant changes.ConclusionHMB improves body composition and sensorimotor function during normal training and attenuates muscle mass and strength loss during catabolic conditions. |
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