The Effect of Hydration on Postprandial Metabolic Responses

Measured using colorimetric assay from venous blood samples

Measured using ELISA from venous blood samples

Measured using freezing point depression from venous blood samples

Determined from haemoglobin and haematocrit measures in blood samples collected before and after drink ingestion

Determined from urine samples collected before and after exercise

Determined from weighing participants before and after exercise

Determined from urine samples collected before and after exercise

Measured via 100 mm visual analogue scales 0 mm = not at all thirsty 100 mm = extremely thirsty

Measured via 100 mm visual analogue scales 0 mm = not at all hungry 100 mm = extremely hungry

Measured via 100 mm visual analogue scales 0 mm = not at all full 100 mm = extremely full

Measured via ingestible pill

Measured via and automated sphygmomanometer

The task will comprise three progressively harder memory loads (1-Back, 2-Back, 3-Back). Each stimulus type will be used in all memory loads. Participants will have to respond using the space bar when they see a stimulus that is presented one, two, or three steps previously, dependent on the load condition. Each phase will comprise 50 trials with ten targets presented centrally on a plain white screen. Each stimulus will be presented for 1000 ms unless the participant responds and in which case the next trial will begin. Commission errors and correct responses will be used as indices of performance. Commission errors occur when participants respond to non-targets.

Participants will be instructed to press the space bar when an image of a tree appears onscreen ("go" stimulus) and to inhibit responding when an image of a football is presented (the "no-go" stimulus). The task will comprise 200 trials, of which 10% will be no-go trials. Each trial will last 500 ms and will have a black image on a white background. The sequence of stimuli will be the same for each participant. In order to allow for pre-potent tendencies to develop, 50 go trials will precede the first no-go trial. Increased commission error responses (i.e. responding incorrectly on a no-go trial) will indicate reduced response inhibition. Commission errors and correct responses will be measured as indices of performance.

Each trial will start with a 1-second instruction screen prompting participants to focus on the target. A central fixation point will be displayed for one second, followed by a brief blank interval and then the appearance of a red distractor. The distractor will appear randomly to the left or right of the fixation point and will remain visible for 2 seconds. Participants will be instructed to maintain fixation at the centre and then make a saccade in the opposite direction as soon as the distractor appears. The task will include 24 trials, with four additional practice trials. The primary variables measured will be reaction time mean and standard deviation, which reflect inhibition latency and variability. Antisaccade errors, or the number of incorrect saccades, will also be calculated.

Each trial will begin with a 1-second instruction screen, followed by a central fixation point and a brief blank interval. A green target then will appear randomly to the left or right of the fixation point for 2 seconds. Participants will be instructed to fixate at the centre and then make a saccade towards the target. The task will include a total of 14 trials, with four additional practice trials. The variables measured will be reaction time mean and standard deviation, which indicate prosaccade latency and variability.

A smooth pursuit task consists of participants following a stimulus with their eyes as it moves in an elliptical pattern on a screen. The stimulus is in motion for 60 seconds. The primary variable measured will be the variability in x and y coordinates of the left and the right eye.