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Fluid balance and exercise performance.
Malays J Nutr 2003; 9(1):53-74MJ

Abstract

Major sporting events in Malaysia are commonly staged in hot environments where the average daytime temperature is generally in the range of 29 to 31°C with the average relative humidity ranging from 80 to 95%. Exercise capacity and exercise performance are reduced when the ambient temperature is high and it has major implications for competitors as well as for spectators and officials. Prolonged exercise leads to progressive water and electrolyte loss from the body as sweat is secreted to promote heat loss. The rate of sweating depends on many factors and increases in proportion to work rate and environmental temperature and humidity. Sweat rates are highly variable and can exceed 2L.h-1 for prolonged periods in high heat. Since dehydration will impair exercise capacity and can pose a risk to health, the intake of fluid during exercise to offset sweat losses is important. Carbohydrate-electrolyte fluid ingestion during exercise has the dual role of providing a source of carbohydrate fuel to supplement the body's limited stores and of supplying water and electrolytes to replace the losses incurred by sweating. The composition of the drinks to be taken will be influenced by the relative importance of the need to supply fuel and water which, in turn depends on the intensity and duration of exercise activity, the ambient temperature, and humidity. Carbohydrate-electrolyte solutions appear to be more effective in improving performance than plain water. There is no advantage to fluid intake during exercise of less than 30-minute duration. Complete restoration of fluid balance after exercise is an important part of the recovery process and becomes even more important in hot, humid conditions. If a second bout of exercise has to be performed after a relatively short interval, the speed of rehydration becomes of crucial importance. Rehydration after exercise requires not only replacement of volume losses, but also replacement of some electrolytes, primarily sodium. Studies show that rehydration after exercise can be achieved only if sweat electrolyte losses as well as water are replaced. Drinks with low sodium content are ineffective at rehydration and they will only reduce the stimulus to drink. Addition of smalls amounts of carbohydrate to the rehydrating drinks may improve the rate of intestinal uptake of sodium and water and will improve palatability. The volume of the rehydration beverage consumed should be greater than the volume of sweat lost to provide the ongoing obligatory urine losses. Palatability of the beverage is a major issue when a large volume of fluid has to be consumed.

Authors+Show Affiliations

Sports Science Unit, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22692532

Citation

Singh, Rabindarjeet. "Fluid Balance and Exercise Performance." Malaysian Journal of Nutrition, vol. 9, no. 1, 2003, pp. 53-74.
Singh R. Fluid balance and exercise performance. Malays J Nutr. 2003;9(1):53-74.
Singh, R. (2003). Fluid balance and exercise performance. Malaysian Journal of Nutrition, 9(1), pp. 53-74.
Singh R. Fluid Balance and Exercise Performance. Malays J Nutr. 2003;9(1):53-74. PubMed PMID: 22692532.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Fluid balance and exercise performance. A1 - Singh,Rabindarjeet,Jr Y1 - 2003/03/15/ PY - 2012/6/14/entrez PY - 2003/3/1/pubmed PY - 2003/3/1/medline SP - 53 EP - 74 JF - Malaysian journal of nutrition JO - Malays J Nutr VL - 9 IS - 1 N2 - Major sporting events in Malaysia are commonly staged in hot environments where the average daytime temperature is generally in the range of 29 to 31°C with the average relative humidity ranging from 80 to 95%. Exercise capacity and exercise performance are reduced when the ambient temperature is high and it has major implications for competitors as well as for spectators and officials. Prolonged exercise leads to progressive water and electrolyte loss from the body as sweat is secreted to promote heat loss. The rate of sweating depends on many factors and increases in proportion to work rate and environmental temperature and humidity. Sweat rates are highly variable and can exceed 2L.h-1 for prolonged periods in high heat. Since dehydration will impair exercise capacity and can pose a risk to health, the intake of fluid during exercise to offset sweat losses is important. Carbohydrate-electrolyte fluid ingestion during exercise has the dual role of providing a source of carbohydrate fuel to supplement the body's limited stores and of supplying water and electrolytes to replace the losses incurred by sweating. The composition of the drinks to be taken will be influenced by the relative importance of the need to supply fuel and water which, in turn depends on the intensity and duration of exercise activity, the ambient temperature, and humidity. Carbohydrate-electrolyte solutions appear to be more effective in improving performance than plain water. There is no advantage to fluid intake during exercise of less than 30-minute duration. Complete restoration of fluid balance after exercise is an important part of the recovery process and becomes even more important in hot, humid conditions. If a second bout of exercise has to be performed after a relatively short interval, the speed of rehydration becomes of crucial importance. Rehydration after exercise requires not only replacement of volume losses, but also replacement of some electrolytes, primarily sodium. Studies show that rehydration after exercise can be achieved only if sweat electrolyte losses as well as water are replaced. Drinks with low sodium content are ineffective at rehydration and they will only reduce the stimulus to drink. Addition of smalls amounts of carbohydrate to the rehydrating drinks may improve the rate of intestinal uptake of sodium and water and will improve palatability. The volume of the rehydration beverage consumed should be greater than the volume of sweat lost to provide the ongoing obligatory urine losses. Palatability of the beverage is a major issue when a large volume of fluid has to be consumed. SN - 1394-035X UR - https://www.unboundmedicine.com/medline/citation/22692532/Fluid_balance_and_exercise_performance_ DB - PRIME DP - Unbound Medicine ER -
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