Published in the Journal of the International Society of Sports Nutrition, the researchers analyzed salivary samples of 20 study participants who consumed one of three beverages to see which would provide a return to a pre-exercise hydration state the fastest.
“Deep-ocean mineral water shows promise as an optimal rehydrating source over spring water and/or sports drink,” the researchers wrote.
Comparing three beverages
Kona Deep, a bottled water company that collects and desalinates ocean water from 3,000 feet under sea level off the coast of Hawaii, approached the scientists for this study. “They wanted to take their water to an independent lab,” Douglas A. Keen, senior lecturer of physiology at the University of Arizona and one of the authors of the study, told FoodNavigator-USA. Though Kona Deep provided the water and initiated the study, the researchers wrote that the study was supported by an Independent Scientist Award from the National Institutes of Health.
“Hydration has always been something of concern to endurance athletes,” he added. “Hydration affects the cardiovascular system because it can affect the drop of blood volume. It’s a hot area of research—whether to have carbohydrates in it or not have carbohydrates and the different minerals in the water—how does it affect hydration?”
One prior study suggests the benefits of deep-sea water for post-exercise hydration. It was conducted in 2013 by Taiwanese scientists using water from the coast of Hualien. “[The] data suggest that deep-ocean mineral water may provide optimal rehydration for performance following high-intensity exercise in well-conditioned individuals,” they wrote.
For this investigation, researchers compared Kona Deep’s hydration performance against mountain spring water (Arrowhead) and a carbohydrate-based sports beverage (Gatorade).
The study design
Participants were eligible if they were student athletes free from alcohol, not on any medications, and without any major health-related issues. A total of 20 participants were randomized into three different groups: 6 were given the Kona Deep water, 8 were given Gatorade, and another 6 were given spring water.
Participants were then fitted with a Polar heart rate monitor and exercised on a stationary bike in 30 degrees Celsius to increase the sweat rate. Taking cue from the Taiwanese study in 2013, a body mass loss of 3% was the target for dehydration.
At each interval, stimulated saliva was collected and salivary osmolality was measured by a vapor pressure osmometer.
“Upon reaching the appropriate body mass loss, subjects were required to consume a volume matching body mass loss such that total volume of intake was equal to body mass loss assuming 1 liter = 1 kg,” the researchers wrote. “Due to the volume of fluid required for the rehydration protocol, subjects were asked to rehydrate in two phases to prevent hypervolemia.”
Every group experienced an increase stimulated salivary osmolality, an indicator of hydration status, along with increased body mass loss during the exercise, and there were no significant differences in the rate of body mass loss at the end of the dehydration process.
However, the researchers saw that participants given deep-ocean water exhibited a more rapid return to baseline salivary osmolality compared to the spring water and sports drink groups.
“The beneficial effects of deep-ocean mineral water may be attributed to its unique mineral composition,” they wrote. “Depletion of these essential minerals, including sodium, calcium, potassium and magnesium may lead to reduced neuromuscular function and physical performance.”
Source: Journal of the International Society of Sports Nutrition
Published online, doi: 10.1186/s12970-016-0129-8
The impact of post-exercise hydration with deep-ocean mineral water on rehydration and exercise performance
Authors: Douglas A. Keen,Eleni Constantopoulos and John P. Konhilas