Efficacy of a Milk Permeate-Based Beverage for Hydration and Exercise Performance
Open Access
- Author:
- Berry, Craig
- Graduate Program:
- Kinesiology
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 16, 2022
- Committee Members:
- Asher Rosinger, Outside Unit & Field Member
Lacy Alexander, Major Field Member
William Kenney, Chair & Dissertation Advisor
Bob Murray, Special Member
David Conroy, Major Field Member
Jonathan Bates Dingwell, Professor in Charge/Director of Graduate Studies - Keywords:
- Hydration
milk-permeate
exercise
dairy
performance
heat - Abstract:
- Fluid homeostasis is challenged during exercise when fluid availability is limited or when fluid loss is not properly replaced. Sports drinks are designed to improve hydration by stimulating fluid ingestion, reabsorption, and retention. Milk has been suggested to be an alternative hydration source to sports drinks due to its higher electrolyte concentrations and similar carbohydrate content. As milk has a high energy density and viscosity that may present gastric discomfort, attempts have been made to develop beverages from milk byproducts, such as milk permeate, that may be more efficacious for consumption during exercise. However, there is limited literature on milk permeate-based beverages for hydration or performance purposes. This dissertation comprises one published literature review and three empirical studies investigation the efficacy of a novel milk permeate-based beverage as an alternative hydration source and its impact on cycling performance. The first study measured the beverage hydration index (BHI), a measure of the hydrating capacity of a given beverage compared to water, of a novel milk permeate solution (MPS) compared to a traditional carbohydrate-electrolyte solution (CES) and water (WAT) in young, well-hydrated individuals at rest in a thermoneutral environment. Our findings indicated that (1) cumulative urine output was attenuated over the entire four hours following consumption of MPS compared to both CES and WAT, resulting in (2) a higher BHI and (3) attenuated reduction in net fluid balance in MPS compared to the other beverages. Further, there was (4) a similar expansion in plasma volume four hours post- CES and MPS consumption compared to WAT. These findings suggest that a beverage containing milk permeate may serve as an efficacious alternative to more traditional CES as a source for hydration in young adults at rest. The second study examined the efficacy of a MPS as a true sports beverage and how consumption of this beverage may impact hydration and cycling time-trial performance in young trained cyclists following exercise- and heat-induced dehydration compared to WAT, a traditional CES, or no fluid (NF) consumption. This study concluded that in a hot-dry environment, (1) cycling performance was improved in each of the beverage trials compared to NF, (2) accompanied by similar expansion in plasma volume in these three beverage conditions, but (3) there were no differences in cycling performance among the three beverage conditions. However, (4) in a subset of subjects completing a slightly longer cycling time-trial in thermoneutral conditions, performance was similarly improved in the CES and MPS conditions compared to WAT. These findings collectively indicate that hydration is more important for improving push-to-the-finish cycling performance in the heat, but carbohydrates play an emerging role in a slightly longer cycling time-trial in thermoneutral conditions. The third study investigated how overnight fluid restriction and subsequent rehydration the following morning with WAT, CES, or MPS impacts cycling time-trial performance in recreational athletes and how these beverages differently influence ad libitum rehydration following moderate-to-vigorous cycling. This study concluded that 1) time-trial performance was not improved following prescribed consumption of a MPS or a traditional CES compared to WAT, 2) ad libitum fluid consumption was not different among beverage conditions during the one-hour recovery cycling period after the time-trial, and 3) changes in plasma volume, an important indicator of hydration, were not different among drink conditions at any time-point, indicating subjects were similarly hydrated among beverage conditions. Together, these three studies provide insight into the hydration efficacy of a milk permeate solution and its effect on cycling performance, suggesting (1) consumption of a milk permeate solution is more hydrating than a traditional sports drink and water at rest, (2) it similarly improves cycling performance as a traditional sports drink compared to water in thermoneutral conditions, but not in the heat, and 3) ad libitum consumption of this milk permeate solution following dehydration does not differ from that of a traditional sports drink or water.