Zadow Emma K, Fell James W, Kitic Cecilia M, Han Jia, Wu Sam S X
Int J Sports Physiol Perform. 2020 Oct 5;15(10):1455-1459. doi: 10.1123/ijspp.2019-0952.
Time of day has been shown to impact athletic performance, with improved performance observed in the late afternoon-early evening. Diurnal variations in physiological factors may contribute to variations in pacing selection; however, research investigating time-of-day influence on pacing is limited.
To investigate the influence of time-of-day on pacing selection in a 4-km cycling time trial (TT).
Nineteen trained male cyclists (mean [SD] age 39.0 [10.7] y, height 1.8 [0.1] m, body mass 78.0 [9.4] kg, VO2max 62.1 [8.7] mL·kg-1·min-1) completed a 4-km TT on 5 separate occasions at 08:30, 11:30, 14:30, 17:30, and 20:30. All TTs were completed in a randomized order, separated by a minimum of 2 d and maximum of 7 d.
No time-of-day effects were observed in pacing as demonstrated by similar power outputs over 0.5-km intervals (P = .78) or overall mean power output (333.0 [38.9], 339.8 [37.2], 335.5 [31.2], 336.7 [35.2], and 334.9 [35.7] W; P = .45) when TTs were performed at 08:30, 11:30, 14:30, 17:30, and 20:30. Preexercise tympanic temperature demonstrated a time-of-day effect (P < .001), with tympanic temperature higher at 14:30 and 17:30 than at 08:30 and 11:30.
While a biological rhythm was present in tympanic temperature, pacing selection and performance when completing a 4-km cycling TT were not influenced by time of day. The findings suggest that well-trained cyclists can maintain a robust pacing strategy for a 4-km TT regardless of time of the day.
一天中的不同时段已被证明会影响运动表现，在傍晚至深夜时段运动表现会有所提升。生理因素的昼夜变化可能会导致配速选择的差异；然而，关于一天中的时段对配速影响的研究有限。
研究一天中的时段对4公里自行车计时赛（TT）中配速选择的影响。
19名训练有素的男性自行车运动员（平均[标准差]年龄39.0[10.7]岁，身高1.8[0.1]米，体重78.0[9.4]千克，最大摄氧量62.1[8.7]毫升·千克⁻¹·分钟⁻¹）在08:30、11:30、14:30、17:30和20:30这五个不同时间点分别完成一次4公里的计时赛。所有计时赛均以随机顺序完成，间隔至少2天，最长7天。
在不同时段进行计时赛时，0.5公里间隔内的功率输出相似（P = 0.78）或总体平均功率输出（分别为333.0[38.9]、339.8[37.2]、335.5[31.2]、336.7[35.2]和334.9[35.7]瓦；P = 0.45），表明配速不受一天中时段的影响。运动前鼓膜温度呈现出一天中的时段效应（P < 0.001），14:30和17:30的鼓膜温度高于08:30和11:30。
虽然鼓膜温度存在生物节律，但在完成4公里自行车计时赛时，配速选择和表现不受一天中时段的影响。研究结果表明，训练有素的自行车运动员在进行4公里计时赛时，无论一天中的什么时间，都能保持稳健的配速策略。
