Leucine metabolites do not attenuate training-induced inflammation in young resistance trained men

• Published in: Journal of sports sciences Vol. 37; no. 17; pp. 2037 - 2044
• Main Authors: Teixeira, Filipe J., Matias, Catarina N., Monteiro, Cristina P., Valamatos, Maria J., Reis, Joana F., Morton, Robert W., Alves, Francisco, Sardinha, Luís B., Phillips, Stuart M.
• Format: Journal Article
• Language: English
• Published: England Routledge 02-09-2019; Taylor & Francis Ltd
• Subjects: Adaptation; C-reactive protein; Calcium; Fat-free body mass; hypertrophy; Inflammation; Interleukin 6; Leucine; leucine metabolites; Metabolites; Physical training; Sarcopenia; Skeletal muscle; strength; Tumor necrosis factor-TNF; Tumor necrosis factor-α; Tumors; Inflammation; strength; hypertrophy; leucine metabolites
• ISSN: 0264-0414; 1466-447X
• DOI: 10.1080/02640414.2019.1617503

Leucine metabolites may reduce training-induced inflammation; however, there is scant evidence for this assertion. We conducted a double-blind randomized controlled pragmatic trial where 40 male participants were allocated into 4 groups: α-hydroxyisocaproic acid group ([α-HICA], n = 10, Fat-free mass [FFM] = 62.0 ± 7.1 kg), β-hydroxy-β-methylbutyrate free acid group ([HMB-FA], n = 11, FFM = 62.7 ± 10.5 kg), calcium β-hydroxy-β-methylbutyrate group ([HMB-Ca], n = 9, FFM = 65.6 ± 10.1 kg) or placebo group ([PLA]; n = 10, FFM = 64.2 ± 5.7 kg). An 8-week whole-body resistance training routine (3 training sessions per week) was employed to induce gains in skeletal-muscle thickness. Skeletal muscle thickness (MT), one repetition maximum (1RM), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP) and tumour necrosis factor alpha (TNF-α) were assessed at baseline and at the end of weeks 4 and 8. Time-dependent increases were detected from baseline to week 8 for MT (vastus lateralis: p = 0.009; rectus femoris: p = 0.018), 1RM (back squat: α-HICA, 18.5% ± 18.9%; HMB-FA, 23.2% ± 16%; HMB-Ca, 10.5% ± 13.8%; PLA, 19.7% ± 9% and bench press: α-HICA, 13.8% ± 19.1%; HMB-FA, 15.5% ± 9.3%; HMB-Ca, 10% ± 10.4%; PLA, 14.4 ± 11.3%, both p < 0.001), IL-6, hsCRP (both p < 0.001) and TNF-α (p = 0.045). No differences were found between groups at any time point. No leucine metabolite attenuated inflammation during training. Additionally, backwards elimination regressions showed that no circulating inflammatory marker consistently shared variance with the change in any outcome. Using leucine metabolites to modulate inflammation cannot be recommended from the results obtained herein. Furthermore, increases in inflammatory markers, from training, do not correlate with any outcome variable and are likely the result of training adaptations.