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.
Age range
18 Years – 35 Years
Sex
ALL
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.
Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.
The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.
A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.
Morning 4-km time-trial finishing time
Timeframe: From enrolment to last experimental session (~4 weeks)
4-km cycling time-trial split times every 1 km.
Timeframe: From familiarisation to the final experimental session (~4 weeks)
Heart rate every 1-km
Timeframe: From familiarisation to the final experimental session (~4 weeks)
Rating of perceived exertion every 1-km
Timeframe: From familiarisation to the final experimental session (~4 weeks)
Perceived pacing taken at 2 and 4 km
Timeframe: From familiarisation to the final experimental session (~4 weeks)
Morning Trail Making Test time to completion in seconds (TMT; parts A and B)
Timeframe: From enrolment to last experimental session (4 weeks)
Morning Rey Auditory Verbal Learning Test
Timeframe: From familiarisation to the final experimental session (~4 weeks)
Morning Stroop word-colour interference test
Timeframe: From familiarisation to the final experimental session (~4 weeks)