We tested the hypothesis that presleep consumption of α-lactalbumin (LA), a fraction of whey with a high abundance of tryptophan, would improve indices of sleep quality and time-trial (TT) performance in cyclists relative to an isonitrogenous collagen peptide (CP) supplement lacking tryptophan. Using randomized, double-blind, crossover designs, cyclists consumed either 40 g of LA or CP 2 hr prior to sleep. In Study 1, six elite male endurance track cyclists (age 23 ± 6 years, V˙O2peak 70.2 ± 4.4 ml·kg-1·min-1) consumed a supplement for three consecutive evenings before each 4-km TT on a velodrome track, whereas in Study 2, six well-trained cyclists (one female; age 24 ± 5 years, V˙O2peak 66.9 ± 8.3 ml·kg-1·min-1) consumed a supplement the evening before each 4-km TT on a stationary cycle ergometer. Indices of sleep quality were assessed with wrist-based actigraphy. There were no differences between the CP and LA supplements in terms of total time in bed, total sleep time, or sleep efficiency in Study 1 (LA: 568 ± 71 min, 503 ± 67 min, 88.3% ± 3.4%; CP: 546 ± 30 min, 479 ± 35 min, 87.8% ± 3.1%; p = .41, p = .32, p = .74, respectively) or Study 2 (LA: 519 ± 90 min, 450 ± 78 min, 87.2% ± 7.6%; CP: 536 ± 62 min, 467 ± 57 min, 87.3% ± 6.4%; p = .43, p = .44, p = .97, respectively). Similarly, time to complete the 4-km TT was unaffected by supplementation in Study 1 (LA: 274.9 ± 7.6 s; CP: 275.5 ± 7.2 s; p = .62) and Study 2 (LA: 344.3 ± 22.3 s; CP: 343.3 ± 23.0 s; p = .50). Thus, relative to CP, consuming LA 2 hr prior to sleep over 1-3 days did not improve actigraphy-based indices of sleep quality or 4-km TT performance in cyclists.

中文翻译：

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睡前 α-乳清蛋白消耗不会改善骑自行车者的睡眠质量或计时赛表现。

我们测试了这样的假设，即睡前消耗 α-乳清蛋白 (LA) 是一种含有大量色氨酸的乳清，相对于等氮胶原肽 (CP ) 补充缺乏色氨酸。使用随机、双盲、交叉设计，骑自行车的人在睡前 2 小时消耗了 40 克 LA 或 CP。在研究 1 中，六名优秀的男性耐力赛道自行车手（年龄 23 ± 6 岁，V˙O2peak 70.2 ± 4.4 ml·kg-1·min-1）在赛车场赛道上的每个 4 公里 TT 之前连续三个晚上服用补充剂，而在研究 2 中，六名训练有素的自行车手（一名女性；年龄 24 ± 5 岁，V˙O2peak 66.9 ± 8.3 ml·kg-1·min-1）在每 4 公里 TT 前一天晚上服用补充剂固定式自行车测力计。睡眠质量指数通过基于手腕的活动记录仪进行评估。在研究 1 中，CP 和 LA 补充剂在总卧床时间、总睡眠时间或睡眠效率方面没有差异（LA：568 ± 71 分钟、503 ± 67 分钟、88.3% ± 3.4%；CP：546 ± 30 分钟、479 ± 35 分钟、87.8% ± 3.1%；分别为 p = .41、p = .32、p = .74）或研究 2（洛杉矶：519 ± 90 分钟、450 ± 78 分钟、87.2% ± 7.6%；CP：536 ± 62 分钟、467 ± 57 分钟、87.3% ± 6.4%；p = .43、p = .44、p = .97）。同样，完成 4 公里 TT 的时间不受研究 1 (LA: 274.9 ± 7.6 s; CP: 275.5 ± 7.2 s; p = .62) 和研究 2 (LA: 344.3 ± 22.3 s; CP: 343.3 ± 23.0 秒；p = .50)。因此，相对于 CP，睡前 2 小时服用 LA 超过 1-3 天并没有改善基于活动记录的睡眠质量指数或骑自行车者的 4 公里 TT 表现。