Fluid Balance and Sodium Losses During Indoor Tennis Match

Research review

Lott, M. E., & Galloway, S. R. (2011). Fluid Balance and Sodium Losses During Indoor Tennis Match Play. International Journal of Sport Nutrition & Exercise Metabolism, 21(6), 492-500.

The purpose of study is to observe the fluid intake strategies, fluid and sodium losses, and match play intensities of elite tennis players in an indoor environment. Before conducting study, they made hypothesize that the sweat rates and body mass deficits recorded would be lower than those reported in previous tennis related studies. If this hypothesize is correct, the players can more readily maintain fluid balance, and considering fluid replacement may not be as necessary as for outdoor warm conditions (2011, p. 492).

For this study, 16 male tennis players participated, and they were graded running test to exhaustion on a treadmill to get VO2peak and did best of three sets singles tennis match conducted indoors. This research was approved by the University Ethics of Research Committee and written informed consent was provided for participants. They also were calculated heart rate to graded intensities of exercise. The data from this test were used to set up three heart rate intensity zones for analysis of the subsequent on court match. In addition, they also were asked to empty bladder and urine volume obtained before nude body mass was recorded. To get sweat volume, 4 sweat patches were used and temperature & humidity were recorded on a digital barometer. They were allowed to consume any drinks but what kind of drinks and how many they drank were recorded. Capillary blood sample was obtained right 3 min after match to analyze for glucose, lactate, and electrolytes (2011, pp. 493-494). 

In the result, we can know there’s no significant difference in body mass and replace percentage of fluid losses from sweating is individually variable (one player replaced only 26% of his fluid losses, whereas another ingested over 200% of fluid lost). Sweat sodium & chloride concentration were significantly higher at the back site than at any other sampling sites. In addition, no significant was observed in sweat osmolality between sampling sites. While urine volume was significantly higher post match than pre match, urine electrolyte concentration & osmolality were not different from pre- to post match. Moreover, blood glucose concentration decreased & blood lactate concentration increased significantly, but plasma sodium, potassium and chloride concentration were not different. Lastly, there’s a significant relationship between whole-body sweat loss and total fluid intake during the matches, but there’s no significant relationship between sweat rate & drinking rate (2011, pp. 495-496). 

However, this study has some limitation related with study period and environment. Since the characteristic of indoor play and this kind sport, there are lower sweat rates and frequent opportunities for fluid intake, every 6-10 min, each change of ends. Therefore, we can easily see moderate ambient indoor temperature conditions players on average do not lose as much sweat as in outdoor warmer environments. However, this point could be inapplicable trait even though it could be applicable for practice, because every real match is conducted outside with sunny and humidity. In addition, although there’s no need to concern right now about different plasma concentration (some players showed non-significant decline), if the match is going longer or subsequently conducted for few days, players such as these may require closer monitoring (2011, pp. 498-499).