Glycaemia
Conditions
Keywords
Hydration, Dehydration, Hypohydration, Glycemia, Glycaemia, Glucose control
Brief summary
Certain populations, such as industrial workers and endurance athletes are particularly susceptible to dehydration due to exposure to heat for long periods of time causing evaporative water loss via sweating. The physical and cognitive decrements associated with dehydration have been widely researched, however the effect of dehydration on metabolism is lesser known. As climate change is causing temperatures to rise, and metabolic diseases such as type 2 diabetes are more common, the effect of dehydration on metabolism, specifically glycemic response to meals, needs to be established for future recommendations in clinical, environmental and athletic settings. Therefore, the aim of this study is to investigate the effect of acute exercise-induced dehydration on subsequent metabolic responses to feeding (i.e. glycaemia and insulinaemia).
Interventions
OTHERWater intake
Water ingested to fully replace sweat losses during exercise.
OTHERWater restriction
Water restriction to induce hypohydration of \ 3% body mass through sweat losses during exercise.
Sponsors
National Institute for Health Research Leicester Biomedical Research Centre
Loughborough University
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
BASIC_SCIENCE
Masking
NONE
Intervention model description
Randomised, crossover design
Eligibility
Sex/Gender
ALL
Age
18 Years to 45 Years
Healthy volunteers
Yes
Inclusion criteria
* Male or female * Generally fit and healthy * Participate in endurance or intermittent exercise at least 3 times a week or minimum of 150 minutes moderate intensity activity per week
Exclusion criteria
* \< 18 or \> 45 * Any health condition that may affect study outcomes (e.g., endocrine/liver/renal/cardiovascular disease) * Any morbidity that affects ability to cycle * Smoker or vaper
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Plasma glucose | 6 hours | Measured using colorimetric assay from venous blood samples |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Urine volume | 6 hours | Determined from urine samples collected before and after exercise |
| Thirst sensation | 6 hours | Measured via 100 mm visual analogue scales 0 mm = not at all thirsty 100 mm = extremely thirsty |
| Hunger sensation | 6 hours | Measured via 100 mm visual analogue scales 0 mm = not at all hungry 100 mm = extremely hungry |
| Fullness sensation | 6 hours | Measured via 100 mm visual analogue scales 0 mm = not at all full 100 mm = extremely full |
| Core body temperature | 6 hours | Measured via ingestible pill |
| Blood pressure | 6 hours | Measured via and automated sphygmomanometer |
| Plasma osmolality | 6 hours | Measured using freezing point depression from venous blood samples |
| Plasma insulin | 6 hours | Measured using ELISA from venous blood samples |
| Plasma volume change | 6 hours | Determined from haemoglobin and haematocrit measures in blood samples collected before and after drink ingestion |
| Body mass | 6 hours | Determined from weighing participants before and after exercise |
| Urine specific gravity/osmolality | 6 hours | Determined from urine samples collected before and after exercise |
Other
| Measure | Time frame | Description |
|---|---|---|
| Oculomotor function antisaccade task | 3 hours | 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. |
| Oculomotor function prosaccade task | 3 hours | 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. |
| Oculomotor function smooth pursuit task | 3 hours | 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. |
| Go/no-go task for response inhibition (cognitive function) | 3 hours | 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. |
| N-back task for working memory (cognitive function) | 3 hours | 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. |
Countries
United Kingdom
Contacts
Primary ContactLewis J James, PhD
Outcome results
None listed