title: The effects of 12 weeks of beta-hydroxy-beta-methylbutyrate free acid supplementation on muscle mass, strength, and power in resistance-trained individuals: a randomized, double-blind, placebo-controlled study.
abstract: BACKGROUND
  Studies utilizing beta-hydroxy-beta-methylbutyrate (HMB) supplementation in trained populations are limited. No long-term studies utilizing HMB free acid (HMB-FA) have been conducted. Therefore, we investigated the effects of 12 weeks of HMB-FA supplementation on skeletal muscle hypertrophy, body composition, strength, and power in trained individuals. We also determined the effects of HMB-FA on muscle damage and performance during an overreaching cycle.
  
  
  METHODS
  A three-phase double-blind, placebo- and diet-controlled randomized intervention study was conducted. Phase 1 was an 8-week-periodized resistance-training program; Phase 2 was a 2-week overreaching cycle; and Phase 3 was a 2-week taper. Muscle mass, strength, and power were examined at weeks 0, 4, 8, and 12 to assess the chronic effects of HMB-FA; and assessment of these, as well as cortisol, testosterone, and creatine kinase (CK) was performed at weeks 9 and 10 of the overreaching cycle.
  
  
  RESULTS
  HMB-FA resulted in increased total strength (bench press, squat, and deadlift combined) over the 12-week training (77.1 ± 18.4 vs. 25.3 ± 22.0 kg, p < 0.001); a greater increase in vertical jump power (991 ± 168 vs. 630 ± 167 W, p < 0.001); and increased lean body mass gain (7.4 ± 4.2 vs. 2.1 ± 6.1 kg, p < 0.001) in HMB-FA- and placebo-supplemented groups, respectively. During the overreaching cycle, HMB-FA attenuated increases in CK (-6 ± 91 vs. 277 ± 229 IU/l, p < 0.001) and cortisol (-0.2 ± 2.9 vs. 4.5 ± 1.7 μg/dl, p < 0.003) in the HMB-FA- and placebo-supplemented groups, respectively.
  
  
  CONCLUSIONS
  These results suggest that HMB-FA enhances hypertrophy, strength, and power following chronic resistance training, and prevents decrements in performance following the overreaching.
authors.affiliation: Department of Health Sciences and Human Performance, The University of Tampa, Tampa, FL, 33606, USA, jwilson06x@gmail.com.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Wilson
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Lowery
authors.forename: Jordan M
authors.initials: JM
authors.lastname: Joy
authors.forename: J C
authors.initials: JC
authors.lastname: Andersen
authors.forename: Stephanie M C
authors.initials: SM
authors.lastname: Wilson
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Stout
authors.forename: Nevine
authors.initials: N
authors.lastname: Duncan
authors.forename: John C
authors.initials: JC
authors.lastname: Fuller
authors.forename: Shawn M
authors.initials: SM
authors.lastname: Baier
authors.forename: Marshall A
authors.initials: MA
authors.lastname: Naimo
authors.forename: John
authors.initials: J
authors.lastname: Rathmacher
mesh_terms: D019587:Dietary Supplements; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D053580:Muscle Strength / Q000187:drug effects*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D055070:Resistance Training; D014631:Valerates / Q000008:administration & dosage / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D014631:Valerates; C004961:beta-hydroxyisovaleric acid