Skip to main content Accessibility help
×
Home

Contents:

Information:

  • Access

Actions:

      • Send article to Kindle

        To send this article to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle. Find out more about sending to your Kindle.

        Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

        Find out more about the Kindle Personal Document Service.

        Milk protein addition to a post-exercise carbohydrate–electrolyte rehydration solution. Is there a dose-response relationship?
        Available formats
        ×

        Send article to Dropbox

        To send this article to your Dropbox account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Dropbox.

        Milk protein addition to a post-exercise carbohydrate–electrolyte rehydration solution. Is there a dose-response relationship?
        Available formats
        ×

        Send article to Google Drive

        To send this article to your Google Drive account, please select one or more formats and confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your <service> account. Find out more about sending content to Google Drive.

        Milk protein addition to a post-exercise carbohydrate–electrolyte rehydration solution. Is there a dose-response relationship?
        Available formats
        ×
Export citation

The ingestion of low-fat milk has been shown to be more effective at restoring fluid balance after exercise-induced dehydration than the ingestion of a commercially available carbohydrate–electrolyte sports drink(1). More recently, it has been shown that after exercise-induced dehydration, the inclusion of 25 g/l milk protein in a carbohydrate–electrolyte rehydration solution increased drink retention in comparison with an isoenergetic, electrolyte content matched carbohydrate solution(2). This suggests that the protein present in milk (~36 g/l) accounts for at least some of the increased drink retention previously reported. It is currently unknown whether there is a dose-response effect of milk protein on drink retention after exercise-induced dehydration. The aim of the present study was to investigate this.

Eight males [mean (sd): age 22 (sd 2) years, height 1.77(sd 0.08) m, body mass 76.96(sd 8.73) kg] completed intermittent exercise in a hot environment [35.0(sd 0.1)°C, 51.8(sd 5.9) relative humidity] until they lost 1.83(sd 0.10)% of their initial body mass. Subjects then ingested a volume of drink in litres equivalent to 150% of their body mass loss in kg. This drink was provided in four aliquots of equal volume at 15 min intervals (0, 15, 30 and 45 min) over a 1 h rehydration period. Subjects then remained in the laboratory for a further 4 h. During each trial, subjects consumed one of the three drinks: a 60 g/l carbohydrate solution (C); a 40 g/l carbohydrate, 20 g/l milk-protein solution (CP20); or a 20 g/l carbohydrate, 40 g/l milk-protein solution (CP40). Drinks were matched in terms of energy density, as well as Na (~20 mmol/l) and K (~5 mmol/l) content. Urine samples were collected before and after exercise, after rehydration and every hour during the 4 h recovery period. Urine samples were measured for volume, osmolality and Na and K concentration. Trials were administered in a double blind, randomised crossover design.

Total cumulative urine output after rehydration was greater for trial C [1150(sd 245) ml] than for trial CP20 [857(sd 270) ml] (P=0.007) and CP40 [769(sd 129) ml] (P=0.006), with no difference between CP20 and CP40 (P=1.000). As a result, total drink retention was greater for CP20 [58(sd 9)%] (P=0.002) and CP40 [64(sd 7)%] (P<0.001) than C [43(sd 7%] (P=0.008), but there was no difference between CP20 and CP40 (P=1.000). At the end of the study period, whole-body net-fluid balance (estimated from fluid lost through sweat and urine production and fluid gained through drink ingestion) was less negative for trials CP20 [−203(sd 315) ml] (P=0.029) and CP40 [−97(sd 146) ]l) (P=0.001) than for trial C [−487(sd 149) ml], but there was no difference between CP20 and CP40 (P=1.000). Although the mean net-fluid balance was negative for all trials at the end of the study, it was only significantly negative after ingestion of drink C (P=0.002).

This study further demonstrates that after exercise-induced dehydration, a carbohydrate–milk protein solution is better retained than a carbohydrate solution, when solutions are matched in terms of energy density, as well as Na and K content. The results also suggest that there is no dose-response relationship between milk-protein ingestion and drink retention after exercise-induced dehydration, at least in the concentrations of milk protein used in this study.

1.Shirreffs, SM, Watson, P & Maughan, RJ (2007) Br J Nutr 98, 173180.
2.James, LJ, Clayton, D & Evans, GH (2011) Br J Nutr 105, 393399.