Effects of calcium beta-hydroxy-beta-methylbutyrate (HMB) supplementation during resistance-training on markers of catabolism, body composition and strength

Calcium beta-hydroxy-beta-methylbutyrate (HMB) supplementation has been rep orted to reduce muscle catabolism and promote gains in fat-free mass and st rength in subjects initiating training. However, whether HMB supplementatio n promotes these adapations in trained athletes is less clear. This study e xamined the effects of HMB (as the calcium salt) supplementation during res istance training (6.9 +/- 0.7 hr x wk(-1)) on markers of catabolism, body c om position a nd strength in experienced resistance-trained males. In a dou ble-blind and randomized manner, 40 experienced resistance-trained athletes were matched and assigned to supplement their diet for 28 d with a fortifi ed carbohydrate/protein powder containing either 0, 3 or 6 g x d(-1) of cal cium HMB. Easting venous blood and urine samples, dual energy X-ray absorpt iometer-determined body composition, and isotonic bench press and leg press one repetition maximums (1 RM) were determined prior to and following 28 d of supplementation. HMB supplementation resulted in significant increases in serum and urinary HMB concentrations. However, no statistically signific ant differences were observed in general markers of whole body anabolic/cat abolic status, muscle and liver enzyme efflux, fat/bone-free mass, fat mass , percent body fat, or 1 RM strength. Results indicate that 28 d of HMB sup plementation (3 to 6 g x d(-1)) during resistance-training does not reduce catabolism or affect training-induced changes in body composition and stren gth in experienced resistance-trained males.