Effects of Caffeine Ingestion on Morning Cognitive and Muscle Repeated Sprint Performance in Males

Morning repeated sprint performance test (10 x 20 m with 30 s recovery) on a vulcanised surfaced runway. With time recorded at 5, 10, 15 and 20 m in seconds.

Morning repeated sprint performance test (10 x 20 m with 30 s recovery) on a vulcanised surfaced runway. With heart rate using a heart rate monitor recorded at the end of each sprint. Takes ~ 1 second.

Morning repeated sprint performance test (10 x 20 m with 30 s recovery) on a vulcanised surfaced runway. With ratine of perceived exertion recorded at the end of each sprint. Takes ~ 1 second. Measured on a 6 (no exertion) to 20 (maximal exertion) scale.

Blood taken from the finger tip and analysed for lactate and glucose levels in mmols. Takes 10 s.

Ear temperature taken at rest and after the warmup. Measured in degrees Celsius. Takes 3 seconds.

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.

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.

Morning grip strength assessed from left and right grip strength on a dynamometer (kg). Takes 4 minutes.

Vertical jump height test (with hands on hips and countermovement jump to measure flight time and height reached; Optojump Next, Microgate, UK. For jump tests variables will be collected on a laptop with associated software (Optojump Next, Microgate, UK). Measured in cm of height.

Performing Witty cognitive agility test (90 s responding to 6 lights on a metal frame where some are at waist level, some shoulder and some at head height at various distances from the volunteer). After each response the participant retreats behind a 1 m line back to starting position (Witty SEM system, Microgate, UK) - test done two times. Each light blocked and the light on the frame was recorded. From far left to far right the lights were numbered 1 to 5 and time was measured in milli seconds.

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 profile of mood states questionnaire (POMS; Version 32) for moods: vigour, tension, calmness, happiness, confusion, depression and fatigue on a visual analogue scale (0=not at all and 4 = extremely). Each mood is the addition of scores for the 4 questions associated with the mood. ~ 60 s each task.

Sleep questions from the Liverpool Jet lag Questionnaire: get to sleep, how well slept, waking time and alertness after waking. Measured on a -5 (later or worst) to +5 scale (more or earlier) where ZERO is compared to normal.

7-day food diary that was analysed using Nutritics® analysis software by a SENr registered Sports and Exercise Nutritionist. Data is presented in macro-nutrients and micro-nutrient diet (mg or g).

Habitual caffeine consumption was assessed using the caffeine consumption questionnaire (CCQ), where caffeine intake was assessed in the morning, afternoon, evening and night. Total daily intake was expressed in mg.

No preference to training regarding time-of-day by a weekly self-reported 2-week training diary for type of exercise, duration, intensity and time of day. With time of day of exercise preference recorded.

Extreme chronotype (assessed via the Composite Morningness Questionnaire) to assess morning, intermediate and evening types. Where Evening type scores 22 and less, Intermediate type 22-43 and Morning type 44 and above.

Poor sleep quality (as indicated by the Pittsburgh sleep quality index global score >5).

Depressed mood severity from the Beck depression inventory (BDI).21 questions were answered (with 4 answers, 0 = I do not feel and 3 = I am so..). The values summated to scores where 0-9 is minimal depression, 10-18 mild and 19-29 moderate depression. 30-63 sever depression. This takes 60 s to complete.

Caffeine withdrawal symptoms (total score) assesses caffeine withdrawal symptoms. Participants were asked to rate each of the 32 questions in terms of how they were feeling at that moment on a 5-pt. scale from 0 (not at all) to 4 (extremely). Eight of the items are positively worded (e.g., energetic) and were reversed scored prior to analyses. At start and during the protocol.