Effect of leucine metabolite beta-hydroxy-beta-methylbutyrate on muscle metabolism during resistance-exercise training.
The effects of dietary supplementation with the leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) were studied in two experiments. In study 1, subjects (n = 41) were randomized among three levels of HMB supplementation (0, 1.5 or 3.0 g HMB/day) and two protein levels (normal, 117 g/day, or high, 175 g/day) and weight lifted for 1.5 h 3 days/wk for 3 wk. In study 2, subjects (n = 28) were fed either 0 or 3.0 g HMB/day and weight lifted for 2-3 h 6 days/wk for 7 wk. In study 1, HMB significantly decreased the exercise-induced rise in muscle proteolysis as measured by urine 3-methylhistidine during the first 2 wk of exercise (linear decrease, P < 0.04). Plasma creatine phosphokinase was also decreased with HMB supplementation (week 3, linear decrease, P < 0.05). Weight lifted was increased by HMB supplementation when compared with the unsupplemented subjects during each week of the study (linear increase, P < 0.02). In study 2, fat-free mass was significantly increased in HMB-supplemented subjects compared with the unsupplemented group at 2 and 4-6 wk of the study (P < 0.05). In conclusion, supplementation with either 1.5 or 3 g HMB/day can partly prevent exercise-induced proteolysis and/or muscle damage and result in larger gains in muscle function associated with resistance training.
Nissen
S
S
Iowa State University, Ames 50011, USA.
Sharp
R
R
Ray
M
M
Rathmacher
J A
JA
Rice
D
D
Fuller
J C
JC
Connelly
A S
AS
Abumrad
N
N
D000328:Adult; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D004032:Diet; D004041:Dietary Fats / Q000494:pharmacology; D004044:Dietary Proteins / Q000494:pharmacology; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology; D006801:Humans; D007930:Leucine / Q000378:metabolism*; D008297:Male; D008762:Methylhistidines / Q000652:urine; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010806:Physical Education and Training; D014631:Valerates / Q000494:pharmacology*; D014891:Weight Lifting
D004041:Dietary Fats; D004044:Dietary Proteins; D008762:Methylhistidines; D009124:Muscle Proteins; D014631:Valerates; C004961:beta-hydroxyisovaleric acid; D007930:Leucine; C028118:3-methylhistidine