The comparison of commercially available coconut water, sports drink and plain water on rehydration and potential benefit for endurance based performance.

Leishman, Andrew (2015) The comparison of commercially available coconut water, sports drink and plain water on rehydration and potential benefit for endurance based performance. MSc(R) thesis, University of Glasgow.

Abstract

Dehydration, the loss of bodily water, results in reduced exercise performance. If athletes become dehydrated, rehydration is essential. Sports drinks are designed to provide fuel for the exercising athlete, and also to help with rehydration. A new alternative to commercial sports drinks is coconut water, which naturally contains electrolytes like potassium, magnesium, calcium and sodium, and natural sugars like glucose and fructose. Our aim was to investigate whether coconut water could be used as a more effective rehydration beverage compared to a sports drink and plain water while using a 150% fluid replacement strategy. As a secondary aspect to the study we investigated whether there were any differences in rehydration capacity for individuals with differing aerobic fitness. With institutional ethics approval, 16 subjects (22.9 ± 3.2 years; height 1.81 ±0.06 m; body mass 75.8 ± 10.2 kg; VO2max 3.98 ± 0.68 l·min-1 ) gave written, informed consent and performed a familiarisation and 3 experimental trials. Subjects exercised on a cycle ergometer (65% of peak work rate) in an environmental chamber (temperature 36.7 ± 0.9ºC, relative humidity 91.9 ± 21.2%) until 2-3% body mass was lost. For 2 hours post-exercise, subjects rehydrated to the equivalent of 150% of body mass lost using coconut water, a sports drink or plain water, administered in a randomised, double-blind crossover manner. In these 2 hours, subject’s nude body mass, urine osmolality and blood glucose were monitored every 30 minutes. Subjects also completed a questionnaire at each 30 minute interval during rehydration. No significant differences were seen between the fluids with regards to body mass regained during the rehydration phase, percentage rehydration or rehydration index. Significance was found in measurements of urine osmolality between coconut water and water at the end of the rehydration phase (P < 0.05), but not between coconut water and the sports drink. With blood glucose, there was a significantly different profile across time between water and the other two fluids.
Although the fitter individuals were found to be able to upregulate sweat rates compared to the less fit subjects, there was no difference found in the rehydration capacity of individuals with differing aerobic fitness levels. Interestingly, the fitter subjects reported feeling more sick throughout the rehydration phase while rehydrating with a sports drink compared to the less fit individuals, this was not seen when subjects rehydrated with coconut water. No significant difference was found between coconut water and the sports drink for blood glucose response throughout the rehydration phase. Further research should therefore aim to investigate the potential use of coconut water during exercise to improve endurance performance. There is no significant difference between Go Coco coconut water and a commercially available sports drink when comparing their ability to rehydrate following dehydrating exercise and that fitter individuals rated feeling more sick while consuming a sports drink compared to coconut water, it is recommended that the naturally occurring coconut water would make an ideal alternative to the manufactured sports drink.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: rehydration, coconut water
• Subjects: Q Science > QP Physiology
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Life Sciences > Life Sciences Human Biology/Sports Science
• Supervisor's Name: Scobie, Mr. Nairn
• Date of Award: 2015
• Depositing User: Mr Andrew J Leishman
• Unique ID: glathesis:2015-6596
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Aug 2015 11:11
• Last Modified: 31 Aug 2015 10:53
• URI: https://theses.gla.ac.uk/id/eprint/6596