title: Effect of beta-hydroxy beta-methylbutyrate on the onset of blood lactate accumulation and V(O)(2) peak in endurance-trained cyclists.
abstract: The purpose of this study was to determine the effect of beta-hydroxy beta-methylbutyrate (HMB) supplementation on maximal oxygen consumption (.V(O)(2)peak) and the onset of blood lactate accumulation (OBLA) in endurance-trained cyclists. Eight cyclists randomly (double blind) completed 3 2-week supplementation periods (HMB, 3g.day(-1); leucine [LEU], 3g.day(-1); placebo [CON], 3g.day(-1)) followed by a 2-week washout period. Testing consisted of a graded cycle ergometry test to measure .V(O)(2)peak and OBLA, the .V(O)(2) at 2 mM blood lactate. .V(O)(2)peak was unaffected by HMB (4.0 +/- 1.4%), LEU (-1.9 +/- 1.3%), and CON (-2.6 +/- 2.6%). HMB resulted in a greater time to reach .V(O)(2)peak, whereas LEU and CON did not affect this time (HMB, 3.6 +/- 1.5 min, LEU, -1.2 +/- 1.5 min; CON, -3.6 +/- 3.5 min). Lactate accumulation peak was unaffected by supplementation (HMB, 8.1 +/- 1.1 mM; LEU, 6.2 +/- 0.8 mM; CON, 7.5 +/- 1.3 mM). OBLA increased with HMB (9.1 +/- 2.4%) and LEU (2.1 +/- 1.5%), but not in the CON trial (0.75 +/- 2.1%). Blood glucose was significantly greater during the HMB trial compared with the LEU trial. It is concluded that HMB supplementation may have positive affects on performance by increasing the onset of blood lactate accumulation; however, the mechanism is unknown.
authors.affiliation: Human Performance Laboratory, Wichita State University, Wichita, Kansas 67260, USA.
authors.forename: M D
authors.initials: MD
authors.lastname: Vukovich
authors.forename: G D
authors.initials: GD
authors.lastname: Dreifort
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000187:drug effects; D000704:Analysis of Variance; D001642:Bicycling / Q000502:physiology*; D001786:Blood Glucose / Q000187:drug effects; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D006400:Hematocrit; D006454:Hemoglobins / Q000187:drug effects; D006801:Humans; D007773:Lactates / Q000097:blood*; D007930:Leucine / Q000008:administration & dosage; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects*; D010806:Physical Education and Training / Q000379:methods; D010807:Physical Endurance / Q000187:drug effects*; D013997:Time Factors; D014631:Valerates / Q000097:blood / Q000494:pharmacology*
chemical_list: D001786:Blood Glucose; D006454:Hemoglobins; D007773:Lactates; D014631:Valerates; C004961:beta-hydroxyisovaleric acid; D007930:Leucine