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THE EFFECTS OF BETA-HYDROXY-BETA-METHYLBUTIRATE (HMB) ON MUSCLE ATROPHY INDUCED BY IMMOBILIZATION

Soares, J M.C.1; Póvoas, S1; Neuparth, M J.1; Duarte, J A.1

Medicine & Science in Sports & Exercise: May 2001 - Volume 33 - Issue 5 - p S140
C30F FREE COMMUNICATION/SLIDE SKELETAL MUSCLE REMODELING: ATROPHY AND HYPERTROPHY
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1Faculty of Sport Sciences, University of Porto, Portugal

email: jmsoares@fcdef.up.pt

Beta-hydroxy-beta-methylbutirate (HMB), a metabolite of leucine via α-ketoisocaproate, is one of the newest dietary supplements promoted to enhance strength and muscle mass. HMB is claimed acting as an anticatabolic agent, minimizing protein breakdown and muscle damage during exercise. In opposition to physical activity, immobilization is a powerful stress agent that increases intracellular catabolism, inducing muscle atrophy and fiber damage.

The aim of this study was to evaluate the effects of HMB administration during hindlimb immobilization on muscle fiber area and cell damage.

Twenty adult male Charles River mice (30–35g weight) were divided in two groups. One of them received a daily dose of 0.002g of HMB (MTI Bio Tech, Inc.) diluted in water (HMB group), while the other group had no drug administration (control group, CTR). The right hindlimb of the mice of both groups was immobilized using a plaster cast for 7 days so that ankle and knee joints were fixed at resting angles. The contralateral leg was used as control. Routine histological procedures of tissue preparation for light microscope examination were used.

The results showed that the HMB group had significantly less damaged fibers (p < 0.05) as was observed through a significant decrease in the number cells with central nuclei (3.6% in CTR vs. 1.6% in HMB) and with alterations of the striation pattern (4.1% in CTR vs. 1.3% in HMB). Furthermore, the decrease in fiber area of the immobilized muscles of the HMB group was significantly less (6.9%) than the control group (p < 0.05). These results suggest that HMB can reduce muscle atrophy and muscle damage induced by immobilization.

©2001The American College of Sports Medicine