Leucine metabolites, α-hydroxyisocaproic acid (α-HICA) and β-hydroxy-β-methylbutyrate (calcium, HMB-Ca and free acid, HMB-FA), have been proposed to augment resistance training-induced changes in body composition and performance.
PURPOSE
We aimed to conduct a double-blind randomized controlled pragmatic trial to evaluate the effects of off-the-shelf leucine metabolite supplements of α-HICA, HMB-FA and HMB-Ca, on resistance training-induced changes in muscle thickness, and performance.
METHODS
Forty men were randomly assigned to receive α-HICA (n=10, fat-free mass [FFM]=62.0 ± 7.1 kg), HMB-FA (n=11, FFM=62.7 ± 10.5 kg), HMB-Ca (n=9, FFM=65.6 ± 10.1 kg), or placebo (PLA; n=10, FFM=64.2 ± 5.7 kg). The training program consisted of whole body thrice weekly resistance training for 8wk (7 exercises/session, 3–4 sets per session, at 70-80% 1RM). Skeletal muscle thickness by ultrasound, performance measures, and blood measures (creatine kinase [CK], insulin-like growth factor 1 [IGF-1], growth hormone [GH], cortisol and total testosterone) were evaluated at baseline and at the end of weeks 4 and 8.
RESULTS
Time-dependent changes were observed for muscle thickness (p < 0.001), 1RM bench press and squat (p < 0.001), Wingate peak power (p = 0.02), countermovement jump height (p = 0.03), power (p = 0.006), CK, IGF-1, GH, and cortisol (all p <0.001). No significant between-group or time-by-group interactions were observed.
CONCLUSION
No leucine metabolite resulted in any ergogenic effects on any outcome variable. Supplementation with leucine metabolites – α-HICA, HMB-FA, or HMB-Ca – is not a supplementation strategy that improves muscle growth and strength development in young adult men.
Leucine Metabolites Do Not Enhance Training-induced Performance or Muscle Thickness.
Medicine & Science in Sports & Exercise: August 10, 2018.
PURPOSE
We aimed to conduct a double-blind randomized controlled pragmatic trial to evaluate the effects of off-the-shelf leucine metabolite supplements of α-HICA, HMB-FA and HMB-Ca, on resistance training-induced changes in muscle thickness, and performance.
METHODS
Forty men were randomly assigned to receive α-HICA (n=10, fat-free mass [FFM]=62.0 ± 7.1 kg), HMB-FA (n=11, FFM=62.7 ± 10.5 kg), HMB-Ca (n=9, FFM=65.6 ± 10.1 kg), or placebo (PLA; n=10, FFM=64.2 ± 5.7 kg). The training program consisted of whole body thrice weekly resistance training for 8wk (7 exercises/session, 3–4 sets per session, at 70-80% 1RM). Skeletal muscle thickness by ultrasound, performance measures, and blood measures (creatine kinase [CK], insulin-like growth factor 1 [IGF-1], growth hormone [GH], cortisol and total testosterone) were evaluated at baseline and at the end of weeks 4 and 8.
RESULTS
Time-dependent changes were observed for muscle thickness (p < 0.001), 1RM bench press and squat (p < 0.001), Wingate peak power (p = 0.02), countermovement jump height (p = 0.03), power (p = 0.006), CK, IGF-1, GH, and cortisol (all p <0.001). No significant between-group or time-by-group interactions were observed.
CONCLUSION
No leucine metabolite resulted in any ergogenic effects on any outcome variable. Supplementation with leucine metabolites – α-HICA, HMB-FA, or HMB-Ca – is not a supplementation strategy that improves muscle growth and strength development in young adult men.
Leucine Metabolites Do Not Enhance Training-induced Performance or Muscle Thickness.
Medicine & Science in Sports & Exercise: August 10, 2018.