Faculty of Rehabilitation Sciences, REVAL - Rehabilitation Research Center, Hasselt University, Diepenbeek, Belgium.
BIOMED - Biomedical Research Institute, Hasselt University, Diepenbeek, Belgium.
J Cachexia Sarcopenia Muscle. 2022 Oct;13(5):2361-2372. doi: 10.1002/jcsm.13048. Epub 2022 Aug 17.
Beta-alanine (BA) supplementation increases muscle carnosine, an abundant endogenous antioxidant and pH buffer in skeletal muscle. Carnosine loading promotes exercise capacity in healthy older adults. As patients with chronic obstructive pulmonary disease (COPD) suffer from elevated exercise-induced muscle oxidative/carbonyl stress and acidosis, and from reduced muscle carnosine stores, it was investigated whether BA supplementation augments muscle carnosine and induces beneficial changes in exercise capacity, quadriceps function, and muscle oxidative/carbonyl stress in patients with COPD.
In this double-blind, randomized, placebo (PL)-controlled trial (clinicaltrials.gov identifier: NCT02770417), 40 patients (75% male) with COPD (mean ± standard deviation: age 65 ± 6 years; FEV % predicted 55 ± 14%) were assigned to 12 weeks oral BA or PL supplementation (3.2 g/day). The primary outcome, i.e. muscle carnosine, was quantified from m. vastus lateralis biopsies obtained before and after intervention. Co-primary outcomes, i.e. incremental and constant work rate cycle capacity, were also assessed. Linear mixed model analyses were performed. Compliance with and side effects of supplement intake and secondary outcomes (quadriceps strength and endurance, and muscle oxidative/carbonyl stress) were also assessed.
Beta-alanine supplementation increased muscle carnosine in comparison with PL in patients with COPD (mean difference [95% confidence interval]; +2.82 [1.49-4.14] mmol/kg wet weight; P < 0.001). Maximal incremental cycling capacity (VO peak: +0.5 [-0.7 to 1.7] mL/kg/min; P = 0.384, Wpeak: +5 [-1 to 11] W; P = 0.103) and time to exhaustion on the constant work rate cycle test (+28 [-179 to 236] s; P = 0.782) did not change significantly. Compliance with supplement intake was similar in BA (median (quartile 1-quartile 3); 100 (98-100)%) and PL (98 (96-100)%) (P = 0.294) groups, and patients did not report side effects possibly related to supplement intake. No change was observed in secondary outcomes.
Beta-alanine supplementation is efficacious in augmenting muscle carnosine (+54% from mean baseline value) without side effects in patients with COPD in comparison with PL. However, accompanied beneficial changes in exercise capacity, quadriceps function, and muscle oxidative/carbonyl stress were not observed.
β-丙氨酸（BA）补充剂可以增加肌肉肌肽，这是一种丰富的内源性抗氧化剂和骨骼肌中的 pH 缓冲剂。肌肽负荷可以提高健康老年人的运动能力。由于慢性阻塞性肺疾病（COPD）患者运动时肌肉氧化/羰基应激和酸中毒增加，肌肉肌肽储存减少，因此研究了 BA 补充剂是否可以增加肌肉肌肽，并诱导 COPD 患者运动能力、股四头肌功能和肌肉氧化/羰基应激的有益变化。
在这项双盲、随机、安慰剂（PL）对照试验（clinicaltrials.gov 标识符：NCT02770417）中，40 名 COPD 患者（75%为男性）（平均±标准差：年龄 65±6 岁；FEV%预测值 55±14%）被分配到 12 周口服 BA 或 PL 补充剂（3.2g/天）。主要结果，即肌肉肌肽，从干预前后获得的股外侧肌活检中进行定量分析。共同的主要结果，即递增和恒功自行车运动能力，也进行了评估。进行线性混合模型分析。还评估了补充剂摄入的依从性和副作用以及次要结果（股四头肌力量和耐力以及肌肉氧化/羰基应激）。
与 PL 相比，BA 补充剂可增加 COPD 患者的肌肉肌肽（平均差异[95%置信区间]；+2.82[1.49-4.14]mmol/kg湿重；P<0.001）。最大递增自行车运动能力（VOpeak：+0.5[-0.7 至 1.7]mL/kg/min；P=0.384，Wpeak：+5[-1 至 11]W；P=0.103）和恒功自行车运动时间测试的衰竭时间（+28[-179 至 236]s；P=0.782）没有显著变化。BA（中位数（四分位距 1-四分位距 3）；100（98-100）%）和 PL（98（96-100）%）（P=0.294）组的补充剂摄入依从性相似，患者未报告可能与补充剂摄入有关的副作用。次要结果没有变化。
与 PL 相比，BA 补充剂在 COPD 患者中有效增加肌肉肌肽（与平均基线值相比增加 54%），且无副作用。然而，没有观察到运动能力、股四头肌功能和肌肉氧化/羰基应激的有益变化。
