Daily L-leucine supplementation in novice trainees during a 12-week weight training program.

What this study found

Daily L-leucine improved strength gains during the 12-week resistance-training program, but it did not show clear added benefit for lean tissue mass or fat loss. In the leucine group, total 5-RM strength increased from 586.0 ± 115.3 kg at baseline to 819.5 ± 129.3 kg at week 12, and gains were significantly greater than placebo for total strength (P < .001) and 5 of 8 exercises, including leg press (P = .010), bench press (P = .02), pullover (P = .03), preacher curls (P = .004), and triceps press (P = .002). Total lean tissue mass changed from 52.0 ± 5.6 to 53.6 ± 5.9 kg (2.9 ± 2.5%), while…

Study & population

Healthy, initially untrained adult men completed a 12-week supervised resistance-training trial in a university gym in Leeds, United Kingdom.

Intervention

Daily oral L-leucine supplementation at 4 g/day (approximately 50 mg/kg body weight/day) as white crystalline powder for 12 weeks.

Key limitation

The trial was short, included only healthy untrained men, and appears to have had limited generalizability.

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