Applied Physiology and Nutrition Research Group, School of Physical Education and Sport; Rheumatology Division; Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, SP, BR, University of São Paulo, Brazil.
Musculoskeletal Physiology Research Group, Sport, Health and Performance Enhancement Research Centre, Nottingham Trent University, United Kingdom.
Eur J Sport Sci. 2022 Aug;22(8):1240-1249. doi: 10.1080/17461391.2021.1940304. Epub 2021 Jun 22.
This study investigated the effect of beta-alanine supplementation on short-duration sprints and final 4-km simulated uphill cycling time-trial performance during a comprehensive and novel exercise protocol representative of the demands of road-race cycling, and determined if changes were related to increases in muscle carnosine content. Seventeen cyclists (age 38 ± 9 y, height 1.76 ± 0.07 m, body mass 71.4 ± 8.8 kg, V̇O 52.4 ± 8.3 ml·kg·min) participated in this placebo-controlled, double-blind study. Cyclists undertook a prolonged intermittent cycling protocol lasting 125 min, with a 10-s sprint every 20 min, finishing with a 4-km time-trial at 5% simulated incline. Participants completed two familiarization sessions, and two main sessions, one pre-supplementation and one post-supplementation following 28 days of 6.4 g·day of beta-alanine (N=11) or placebo (N=6; maltodextrin). Muscle biopsies obtained pre- and post-supplementation were analysed for muscle carnosine content. There were no main effects on sprint performance throughout the intermittent cycling test (all >0.05). There was no group (=0.69), time (=0.50) or group x time interaction (=0.26) on time-to-complete the 4-km time-trial. Time-to-completion did not change from pre- to post-supplementation for BA (-19.2 ± 45.6 s, =0.43) or PL (+2.8 ± 31.6 s, =0.99). Beta-alanine supplementation increased muscle carnosine content from pre- to post-supplementation (+9.4 ± 4.0 mmol·kgdm; <0.0001) but was not related to performance changes (r=0.320, =0.37). Chronic beta-alanine supplementation increased muscle carnosine content but did not improve short-duration sprint performance throughout simulated road race cycling, nor 4-km uphill time-trial performance conducted at the end of this cycling test.Performance during prolonged cycling events often depends on the ability to maintain an increased power output during higher intensity periods. Thus, cyclists are likely heavily dependent on their ability to resist fatigue during these periods of high-intensity activity.Meta-analytical data show beta-alanine to be an effective supplement to improve exercise outcomes, but little work exists on its efficacy during dynamic actions that are common during prolonged cycling.Beta-alanine supplementation increased muscle carnosine content but did not generate improvements in the performance of high-intensity cycling (10-s sprints or 4-km uphill time-trial) during a simulated road race cycling protocol.These data suggest that short duration sprints (≤10 s) and longer duration (>10 min) high-intensity activity throughout endurance cycling may not be improved with beta-alanine supplementation despite increases in muscle carnosine content.
本研究旨在探讨β-丙氨酸补充对综合新颖运动方案中短时间冲刺和最后 4 公里模拟上坡计时赛表现的影响，该方案代表了公路自行车赛的需求，并确定这些变化是否与肌肉肉毒碱含量的增加有关。17 名自行车运动员（年龄 38±9 岁，身高 1.76±0.07m，体重 71.4±8.8kg，V̇O 52.4±8.3ml·kg·min）参与了这项安慰剂对照、双盲研究。自行车运动员进行了长达 125 分钟的长时间间歇式自行车测试，每 20 分钟进行 10 秒冲刺，最后以 5%模拟坡度进行 4 公里计时赛。参与者完成了两次熟悉阶段和两次主要阶段，一次是补充前，一次是补充后，持续 28 天，每天补充 6.4gβ-丙氨酸（N=11）或安慰剂（N=6；麦芽糊精）。补充前后采集肌肉活检标本，分析肌肉肉毒碱含量。在整个间歇式自行车测试中，冲刺表现均无主要影响（均>0.05）。无组间（=0.69）、时间（=0.50）或组间×时间交互作用（=0.26）对 4 公里计时赛的完成时间有影响。BA（-19.2±45.6s，=0.43）或 PL（+2.8±31.6s，=0.99）补充前后的完成时间均未发生变化。β-丙氨酸补充使肌肉肉毒碱含量从补充前到补充后增加（+9.4±4.0mmol·kgdm；<0.0001），但与性能变化无关（r=0.320，=0.37）。慢性β-丙氨酸补充增加了肌肉肉毒碱的含量，但并没有提高模拟公路自行车赛期间的短时间冲刺表现，也没有提高该自行车测试结束时的 4 公里上坡计时赛表现。长时间骑行比赛的表现往往取决于在高强度时期维持更高功率输出的能力。因此，自行车运动员在这些高强度活动期间可能严重依赖于抵抗疲劳的能力。荟萃分析数据显示，β-丙氨酸是一种有效的补充剂，可以改善运动效果，但在长时间骑行中常见的动态动作中，其效果的研究很少。β-丙氨酸补充增加了肌肉肉毒碱的含量，但在模拟公路赛车自行车方案中，高强度自行车运动（10 秒冲刺或 4 公里上坡计时赛）的表现没有提高。这些数据表明，尽管肌肉肉毒碱含量增加，但短时间冲刺（≤10 秒）和长时间（>10 分钟）的高强度耐力自行车运动可能不会因β-丙氨酸补充而得到改善。
