This study aimed to determine if belief in caffeine's ergogenic potential influences choice reaction time (CRT) and/or running performance. Twenty-nine healthy individuals (23.7 ± 5 years, 16 males) completed two trials (one week apart). Before the trials, participants indicated their “belief” in caffeine's ergogenic effects and previous “experience” using caffeine for performance. On arrival, participants randomly received either sham “Low (100mg; LD)” or “High (300mg; HD)” dose caffeine capsules 30-min before commencing the CRT test, followed by a 10km run. Paired samples t-tests determined differences between trials for CRT latency (Ex-Gaussian analysis; μ-, σ- and τ-) and running performance using the entire cohort and sub-groups exhibiting strong “beliefs”+/−“experience”. Sham caffeine dose did not influence CRT (μ-, σ- and τ-respectively, LD: 400 ± 53ms vs. HD: 388 ± 41ms; LD: 35 ± 18ms vs. HD: 34 ± 17ms; LD: 50 ± 24ms vs. HD: 52 ± 19ms, all p's > 0.05). Neither belief (n = 6), nor belief + experience (n = 4), influenced this effect. Furthermore, caffeine dose did not influence run time (LD: 49.05 ± 3.75min vs. HD: 49.06 ± 3.85min, p = 0.979). Belief (n = 9) (LD: 48.93 ± 3.71min vs. HD: 48.9 ± 3.52min, p = 0.976), and belief + experience (n = 6) (LD: 48.68 ± 1.87min vs. HD: 49.55 ± 1.75min, p = 0.386) didn't influence this effect. A dose-response to sham caffeine ingestion was not evident on cognitive or endurance performance in healthy individuals, regardless of their convictions about caffeine's ergogenicity.

中文翻译：

---

相信咖啡因对认知功能和耐力表现的增效作用：一项虚假的剂量反应研究

本研究旨在确定对咖啡因的增效潜力的信念是否会影响选择反应时间 (CRT) 和/或跑步表现。29 名健康人（23.7 ± 5 岁，16 名男性）完成了两项试验（相隔一周）。在试验之前，参与者表明他们对咖啡因的增效作用的“信念”以及之前使用咖啡因提高表现的“经验”。抵达后，参与者在开始 CRT 测试前 30 分钟随机接受假“低（100mg；LD）”或“高（300mg；HD）”剂量咖啡因胶囊，然后进行 10 公里跑步。配对样本t检验确定了 CRT 延迟试验之间的差异（前高斯分析; μ-、σ- 和 τ-) 以及使用表现出强烈“信念”+/-“经验”的整个队列和子组的跑步表现。假咖啡因剂量不影响 CRT（分别为 μ-、σ- 和 τ-，LD：400 ± 53ms vs. HD：388 ± 41ms；LD：35 ± 18ms vs. HD：34 ± 17ms；LD：50 ± 24ms vs. .HD：52 ± 19ms，所有p > 0.05)。信念（n  = 6）和信念+经验（n  = 4）都不会影响这种效果。此外，咖啡因剂量不影响运行时间（LD：49.05 ± 3.75min vs. HD：49.06 ± 3.85min，p  = 0.979）。信念 ( n  = 9) (LD: 48.93 ± 3.71min vs. HD: 48.9 ± 3.52min, p  = 0.976)，信念 + 经验 ( n  = 6) (LD: 48.68 ± 1.87min vs. HD: 49.55 ± 1.75分钟，p  = 0.386）不影响这种效果。健康个体的认知或耐力表现对假摄入咖啡因的剂量反应并不明显，无论他们对咖啡因的增效作用的信念如何。