Leucine metabolites and muscle growth in young men
What it found
In men doing resistance training for 8 weeks, leucine metabolite supplements did not improve muscle thickness or performance.
The authors say these supplements are not a strategy that improves muscle growth and strength.
What they found
Studies in people
Muscle thickness
Muscle thickness changed over time in all groups, but there was no significant difference between the supplement groups and the placebo group.
Strength and power
One repetition maximum bench press and squat, Wingate peak power, countermovement jump height, and power all changed over time, but no supplement group differed significantly from placebo.
Blood measures
Creatine kinase, insulin-like growth factor 1, growth hormone, and cortisol changed over time, but there were no significant differences between groups.
No ergogenic effect
No leucine metabolite resulted in any ergogenic effects on any outcome variable.
What the authors conclude
“No leucine metabolite resulted in any ergogenic effects on any outcome variable.”
Also in their conclusions
- They conclude that no leucine metabolite resulted in any ergogenic effects on any outcome variable.
- They advise that 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.
How it was done
Leucine metabolites have been proposed to boost the changes in body composition and performance that come with resistance training.
Forty men were randomly assigned to take α-HICA, HMB-FA, HMB-Ca, or a placebo while doing whole body resistance training three times a week for 8 weeks. Muscle thickness by ultrasound, performance measures, and blood measures were checked at the start and at the end of weeks 4 and 8.
What it can’t tell you
- We summarised it from the abstract only.
- This trial was in young adult men doing resistance training, so the results may not apply to other groups.
- The study lasted 8 weeks, so it cannot show what might happen with longer use.
Who paid
- Authors work at
- Laboratory of Physiology and Biochemistry of Exercise, PORTUGAL; Laboratory of Exercise and Health, PORTUGAL; Center for the Study of Human Performance, PORTUGAL
The paper
- Title
- Leucine Metabolites Do Not Enhance Training-induced Performance or Muscle Thickness
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Teixeira FJ, Matias CN, Monteiro CP, et al (2019). Leucine Metabolites Do Not Enhance Training-induced Performance or Muscle Thickness. Medicine and science in sports and exercise. doi:10.1249/MSS.0000000000001754PubMed 30102677DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error