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Completed

NCT Number: NCT07468539

Post-exercise Rehydration: A Randomised Cross-over Trial Comparing a 100% Fruit Beverage, a Glucose-based Sports Drink, and Water

It is well-established that exercise has many health benefits. During exercise in temperate/hot conditions, sweating is necessary to dissipate heat. This sweating typically results in dehydration, which may impair physical and mental performance. Therefore, following exercise, effective rehydration is important to restore an optimal hydration state and therefore physical and mental performance. If an individual only rehydrates with water, though, it is unlikely that they will fully rehydrate as plain water is not very well-retained by the body, due to its lack of carbohydrate and electrolytes. For this reason, sports/ hydration drinks are likely to aid in better rehydration, due to their carbohydrate and electrolyte content. This project aims to compare the rehydration effectiveness and glucose responses to two sports / hydration drinks and water (with different carbohydrate and electrolyte contents).

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Key information

Conditions

Dehydration Metabolic Diseases Nutritional and Metabolic Diseases Pathologic Processes Pathological Conditions, Signs and Symptoms Water-Electrolyte Imbalance

Age range

18 year–50 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Nottingham Trent University, Clifton Campus

Nottingham, NG11 8NS, United Kingdom

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Training/performing > 1 hrs a week

Exclusion criteria

  • Smoker.
  • Pregnant, attempting to become pregnant, or breastfeeding.
  • Diabetic.
  • You have adverse events/reactions in response to fingertip capillary blood sampling which includes, but is not limited to; fainting and/or serious bruising.
  • History of heat-related illness.
  • History of heart failure, pulmonary hypertension, embolism, or other pulmonary heart disease.
  • Previously diagnosed with COPD, emphysema, bronchitis or similar respiratory illness.
  • Have a history of severe allergic reactions.
  • History of kidney issues.
  • Regular use of non-steroidal anti-inflammatory medications.
  • Any other medical conditions / medications that may interfere with an individuals ability to safely perform exercise in the heat and experience dehydration.
  • Allergies/intolerances to any of the following ingredients: Glucose Syrup, Acid (Citric Acid), Acidity Regulator (Sodium Citrate), Extract of Black Carrot, Watermelon, pomegranate, lime, Preservatives (Potassium Sorbate, Dimethyl Dicarbonate), Stabilisers (Acacia Gum), Sweeteners (Aspartame, Acesulfame K), Antioxidant (Ascorbic Acid), Flavourings, Niacin (Vitamin B3).
  • Elite athlete subject to doping tests

Treatment and study plan

Water

Other

Consumption of a water volume (from water) equal to 150% of body mass loses from exercise-induced hypohydration

Glucose-based sports drink

Other

Consumption of a water volume (from a glucose-based sports drink) equal to 150% of body mass loses from exercise-induced hypohydration

Fruit beverage

Other

Consumption of a water volume (from a fruit beverage) equal to 150% of body mass loses from exercise-induced hypohydration

Primary outcomes

  1. Net water Balance

    Time frame: Baseline (pre-exercise), post-exercise, and 0, 1, 2, 3, and 4 h post-rehydration

    ([post-exercise body mass (kg) - Pre-exercise body mass (kg)] x 1000) + water volume consumed (g) - cumulative urine output during rehydration period (g)

  2. Cumulative urine volume

    Time frame: 0, 1, 2, 3, and 4 h post-rehydration

  3. Total urine volume

    Time frame: Sum of urine produced at 0, 1, 2, 3, and 4 h post-rehydration

    Total urine volume produced during the rehydration period

  4. Water retention

    Time frame: 4 h post-rehydration

    ([water volume consumed (g) - total urine volume produced during the rehydration period (g)] / water volume consumed (g)) x 100

Secondary outcomes

  1. Blood glucose concentration

    Time frame: Baseline (pre-exercise), post-exercise, and 0, 0.25, 0.5, 0.75, 1, 1.5, and 2 h post-rehydration

  2. Blood glucose area under the curve

    Time frame: The 2h period following rehydration

  3. Hyperglycaemia incidence

    Time frame: The 2 h period following rehydration

    Number of participants that experience blood glucose > 7.8 mmol/L

  4. Hypoglycaemia incidence

    Time frame: The 2 h period following rehydration

    The number of participants that experience blood glucose < 3.9 mmol/L

  5. Urine osmolality

    Time frame: Baseline (pre-exercise), post-exercise, and 0, 1, 2, 3, and 4 h post-rehydration

    A measure of urine concentration.

  6. Body mass

    Time frame: Baseline (pre-exercise) and post-exercise (approximately 2 h post-baseline, depending on sweat losses during cycling in the heat)

    Body mass in kilograms at baseline compared across trials. Body mass loss (both in grams and as a percentage) from pre-exercise to post-exercise compared across trials.

  7. Thirst

    Time frame: Baseline (pre-exercise), towards the end of each 10 minute block of exercise (cycling in the heat), post-exercise, and 0, 1, 2, 3, and 4 h post-rehydration

    Participants asked to rate their thirst on a scale of 0-10 (0 = no symptom, 10 = maximum symptom)

  8. Gastrointestinal comfort

    Time frame: Baseline (pre-exercise), post-exercise, and 0, 1, 2, 3, and 4 h post-rehydration

    Participants asked to rate their gastrointestinal comfort on a scale of 0-10 (0 = no symptom, 10 = maximum symptom)

  9. Rating of perceived exertion (RPE)

    Time frame: Measured towards the end of each 10 minute block of exercise (cycling in the heat). Up to 8 blocks lasting a total of 120 minutes (10 minutes of cycling, followed by 5 minutes of rest), depending on body mass loss.

    Participants asked to rate their RPE on a scale of 6-20. This is a measure of exercise intensity. Average taken for dehydration period. Average compared across trials.

  10. Thermal sensation

    Time frame: Measured towards the end of each 10 minute block of exercise (cycling in the heat). Up to 8 blocks lasting a total of 120 minutes (10 minutes of cycling, followed by 5 minutes of rest), depending on body mass loss.

    Participants asked to rate their thermal sensation on a scale of -10 (unbearably cold) to 10 (unbearably hot). Average taken for dehydration period. Average compared across trials.

  11. Time in environmental chamber

    Time frame: Up to 120 minutes, depending on body mass losses during cycling in the heat

    The time in minutes that the participant spent in the environmental chamber at 35 degrees Celsius, doing repeated blocks of 10 minutes of cycling followed by 5 minutes of rest, until they reached approximately 1.5% body mass loss. Time compared across trials.

  12. Laboratory temperature

    Time frame: Baseline (pre-exercise), post-exercise, and 0, 1, 2, 3, and 4 h post-rehydration

    Temperature (degrees Celsius) of the laboratory measured across the day and averaged. Averages compared across trials.

  13. Environmental chamber temperature

    Time frame: Measured towards the end of each 10 minute block of exercise (cycling in the heat). Up to 8 blocks lasting a total of 120 minutes (10 minutes of cycling, followed by 5 minutes of rest), depending on body mass loss.

    Environmental chamber temperature (degrees Celsius) measured and averaged for the cycling in the heat period of each participant. Averages compared across trials.

  14. Laboratory humidity

    Time frame: Baseline (pre-exercise), post-exercise, and 0, 1, 2, 3, and 4 h post-rehydration

    Humidity (relative humidity) of the laboratory measured across the day and averaged. Averages compared across trials.

  15. Environmental chamber humidity

    Time frame: Measured towards the end of each 10 minute block of exercise (cycling in the heat). Up to 8 blocks lasting a total of 120 minutes (10 minutes of cycling, followed by 5 minutes of rest), depending on body mass loss.

    Environmental chamber humidity (relative humidity) measured and averaged for the cycling in the heat period of each participant. Averages compared across trials.

Sponsors and collaborators

Lead sponsor

Nottingham Trent University

Other

Collaborators

  • Innate-Essence Limited

Registry information

Official study title

Comparing The Rehydration Properties Of Two Sports / Hydration Drinks And Water, Following Exercise In The Heat

Important dates

Study start
2024
Primary completion
2025
Study completion
2025
First posted
Mar 12, 2026
Registry last updated
Mar 12, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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