Effects of Caffeine Ingestion on Morning Cognitive and 4-km Time Trial Performance in Males. Where a Standardized Approach Has Been Employed
试验速览
- 阶段
- 1 期
- 状态
- 进行中（未招募）
- 入组人数
- 15
- 试验地点
- 1
- 主要终点
- Morning 4-km time-trial finishing time
研究概览
简要总结
Athletes often compete in the morning when they are biologically weaker; normally in competition heats or quarterfinals to qualify for the finals scheduled in the evening. Some athletes may even choose to perform at submaximal levels in these qualifying rounds, especially when they are expected to perform multiple times in the same day (such as weightlifting at the Olympic Games). Gross muscular performance such as power output or force production is greater in the evening than the morning (~3-14% variation). Similarly, time-trial performance and repeated sprint performance (RSP; a good measure of performance in team sport) is ~3 and 5 % greater in the evening than the morning.
The reason for this daily variation in performance is attributed to central factors (such as the body clock), as well as motivational and peripheral factors, including higher core and muscle temperatures in the evening compared to the morning. The body clock located within the anterior hypothalamus consists of a group of neurons known as suprachiasmatic nuclei, which are responsible for controlling the rhythm of core temperature.
The most efficient nutritional ergogenic is caffeine. Recently caffeine has been investigated to reduce the negative influence of diurnal variations on repeated-sprint ability test (10 × 6 s cycle sprints, with 30 s of rest) at 60 min after ingestion of either 5 mg·kg-1 or placebo. Lopes-Silva et al. (2019) reported that caffeine supplementation did not prevent the reduction in performance in the morning. However, placebo effect can be 3-5% and hence the use of a No-pill condition would ensure that any placebo effect is accounted for and that the true potential effect of caffeine can be established.
To the best of our knowledge, no study has yet investigated caffeine (CAFF), NoPill (NOPILL) or Placebo (PLAC) effects on cognitive and 4-km time-trial (TT) performance. As a diurnal variation in 4-km TT has been widely reported in a similar population. The aim of the present study is to investigate if ingesting caffeine on the day of the morning test, to improve performance.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Crossover
- 主要目的
- Treatment
- 盲法
- Double (Participant, Investigator)
盲法说明
Both researcher and participants did not know what of the two pill options were caffeine
入排标准
- 年龄范围
- 18 Years 至 35 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Healthy adults
- •18-35 years old
- •Injury-free
- •≥ 2 years of weight/strength training experience
- •Not receiving any pharmacological treatment (including non-steroidal anti-inflammatory drugs, NSAIDs) throughout the study period
- •Low habitual caffeine consumers (≤ 150mg per day)
- •No preference to training regarding time-of-day
排除标准
- •Depressed mood (from the Beck depression inventory)
- •Poor sleep quality (a Pittsburgh sleep quality index global score >5
- •Recent shift work or travel across multiple time-zones
- •Extreme chronotype (assessed via the Composite Morningness Questionnaire
- •Risk factors and/ or symptoms of cardiovascular disease.
研究组 & 干预措施
Group 1
1) NoPill, 2) PLAC, 3) Caffeine (300 mg)
干预措施: No Pill (Other)
Group 2
1) PLAC, 2) Caffeine (300 mg), 3) NoPill,
干预措施: Caffeine (300 mg) (Drug)
Group 2
1) PLAC, 2) Caffeine (300 mg), 3) NoPill,
干预措施: Placebo (Other)
Group 2
1) PLAC, 2) Caffeine (300 mg), 3) NoPill,
干预措施: No Pill (Other)
Group 1
1) NoPill, 2) PLAC, 3) Caffeine (300 mg)
干预措施: Caffeine (300 mg) (Drug)
Group 1
1) NoPill, 2) PLAC, 3) Caffeine (300 mg)
干预措施: Placebo (Other)
Group 3
1) Caffeine (300 mg) 2) NoPill, 3) PLAC
干预措施: Caffeine (300 mg) (Drug)
Group 3
1) Caffeine (300 mg) 2) NoPill, 3) PLAC
干预措施: Placebo (Other)
Group 3
1) Caffeine (300 mg) 2) NoPill, 3) PLAC
干预措施: No Pill (Other)
结局指标
主要结局
Morning 4-km time-trial finishing time
时间窗: From enrolment to last experimental session (~4 weeks)
4-km cycling time-trial (Watbike Pro, Nottingham UK) finishing time in minute and seconds. \~ 4-6 minutes.
4-km cycling time-trial split times every 1 km.
时间窗: From familiarisation to the final experimental session (~4 weeks)
4-km cycling time-trial (Watbike Pro, Nottingham UK) split times (in minutes and seconds) every 1 km.
Heart rate every 1-km
时间窗: From familiarisation to the final experimental session (~4 weeks)
Heart rate measured every 1-km during the 4-km time-trial, using a heart rate monitor.
Rating of perceived exertion every 1-km
时间窗: From familiarisation to the final experimental session (~4 weeks)
Rating of perceived exertion every 1-km for the 4-km time-trail. Measured on a 6 (no exertion) to 20 (maximal exertion) scale. Takes \~1 s.
Perceived pacing taken at 2 and 4 km
时间窗: From familiarisation to the final experimental session (~4 weeks)
Perceived pacing taken at 2 and 4 km of the 4-km time trial. The scale is a 10 cm visual analogue scale where -5 represents pacing to slow to complete the 2 km as fast as possible, zero = optimal pacing and +5 went to fast. Takes \~1 s to answer.
Morning Trail Making Test time to completion in seconds (TMT; parts A and B)
时间窗: From enrolment to last experimental session (4 weeks)
To assess the effect of 300 mg caffeine (CAFF) vs placebo (PLAC) vs no-pill (NoPill) on morning Trail Making Test time to completion in seconds (TMT; parts A and B). In part A the circles are numbered 1-25, and the participant is instructed to draw lines to connect the numbers in ascending order. In part B, the circles include both numbers (1-13) and letters (A-L) and the participant is instructed to draw lines to connect the circles in ascending pattern but with the added task of alternating between numbers and letters (i.e., 1-A-2-B-3-C etc.). In both parts the participant is instructed to connect to the circles as fast as possible, without lifting the pencil from the paper. If an error is made, this is pointed out immediately and the participant is allowed to correct it. During the test, time to completion is measured, with a higher time indicative of the greater impairment.
Morning Rey Auditory Verbal Learning Test
时间窗: From familiarisation to the final experimental session (~4 weeks)
Rey Auditory Verbal Learning Test: The RAVLT is a neuropsychological assessment designed to evaluate verbal memory. The test is designed as a list-learning paradigm in which the volunteer hears a list of 15 nouns and is asked to recall as many words from the list as possible. The number correct and the number that were given by the participant but not on the list (intrusions) are noted. This process is re-peated 4 more times. The process is repeated but with a second interference list (List B) is presented in the same manner, and the participant is asked to recall as many words as possible from List B and scoring recorded. . After the interference trial, the participant is immediately asked to recall the words from List A, which they heard five times previously and the number of correct words and intrusions are recorded. RAVTL total number, number of dis-tractions and retention are recorded and analysed.
Morning Stroop word-colour interference test
时间窗: From familiarisation to the final experimental session (~4 weeks)
Stroop word-colour interference test. The participants were asked to read out their responses to words or colours for 45 s as quickly as possible and to leave no errors uncorrected. This was filmed and the number of errors and total amount completed was recorded and analysed. The first sheet had text (red, blue, yellow, black and green) in black ink (naming word test, W). The second sheet had blocks of colour corresponding to the text on the first sheet (naming colour test, C). With the third sheet, the participants had to read out the word (which was coloured differently to the word, e.g., the word was yellow and the colour red, referred to as the naming colour of word test, CW) and for the fourth sheet, the participants had to read out the colon (which was wrongly named, e.g., the colour was yellow but the word was red, referred to as the naming of word not colour test, WC). In this fourth sheet, the words were printed in the reverse order to the third sheet.
次要结局
- Rectal temperature @rest and after warm-up(From enrolment to last experimental session (4 weeks))
- Blood lactate @ rest, pre TT and after(From enrolment to last experimental session (4 weeks))
- Mean skin temperature (Tsk)(From familiarisation to the final experimental session (~4 weeks))
- The mean body temperature (Tmb)(From familiarisation to the final experimental session (~4 weeks).)
- Morning profile of mood states questionnaire(From familiarisation to the final experimental session (~4 weeks))
- Sleep questions from the Liverpool Jet lag Questionnaire(From familiarisation to the final experimental session (~4 weeks))
- 7-day food diary(Baseline)
- Habitual caffeine consumption(Baseline)
- Self-reported 2-week training diary(Baseline)
- Chronotype(Baseline)
- Poor sleep quality(At the start of the study as part of exclusion criteria)
- Depressed mood(Baseline)
- Caffeine withdrawal symptoms score(From familiarisation to the final experimental session (~4 weeks).)
研究者
spsbedwa@ljmu.ac.uk
Reader Chronobiology and Environmental Physiology
Liverpool John Moores University