The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Michael N. Sawka - One of the best experts on this subject based on the ideXlab platform.
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Fluid Replacement and performance during the marathon.
Sports Medicine, 2007Co-Authors: Samuel N Cheuvront, Scott J. Montain, Michael N. SawkaAbstract:The primary purpose of this review is to relate a universal strategy for replacing Fluids to optimise marathon performance. A secondary purpose is to examine common ‘matters of debate’ that may modify Fluid needs to include the importance of realistic convective air flow, metabolic water production and waters of association with glycogen. The metabolic demands of marathon running can result in substantial sweat losses and levels of dehydration consistent with compromised endurance performance. Recommendations are provided to individualise Fluid intakes with the goal of preventing excessive dehydration (>2% body mass) as well as weight gain. The minor importance of ‘matters of debate’ to Fluid Replacement is also discussed.
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American College of Sports Medicine position stand. Exercise and Fluid Replacement.
Medicine and science in sports and exercise, 2007Co-Authors: Michael N. Sawka, Scott J. Montain, Louise M Burke, E Randy Eichner, Ronald J Maughan, Nina S StachenfeldAbstract:This Position Stand provides guidance on Fluid Replacement to sustain appropriate hydration of individuals performing physical activity. The goal of prehydrating is to start the activity euhydrated and with normal plasma electrolyte levels. Prehydrating with beverages, in addition to normal meals and Fluid intake, should be initiated when needed at least several hours before the activity to enable Fluid absorption and allow urine output to return to normal levels. The goal of drinking during exercise is to prevent excessive (>2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance. Because there is considerable variability in sweating rates and sweat electrolyte content between individuals, customized Fluid Replacement programs are recommended. Individual sweat rates can be estimated by measuring body weight before and after exercise. During exercise, consuming beverages containing electrolytes and carbohydrates can provide benefits over water alone under certain circumstances. After exercise, the goal is to replace any Fluid electrolyte deficit. The speed with which rehydration is needed and the magnitude of Fluid electrolyte deficits will determine if an aggressive Replacement program is merited.
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Current U.S. Military Fluid Replacement Guidelines
2003Co-Authors: Margaret A. Kolka, Scott J. Montain, Michael N. Sawka, William A. Latzka, Kansas StreetAbstract:This paper presents a summary of the process to revise the U.S. Military’s Fluid Replacement Guidelines. The “old” Fluid Replacement guidelines provided recommendations for Fluid Replacement based solely on climatic conditions without consideration for energy expended (activity level) or without hourly or daily limits on Fluid consumption. The “revised” Fluid Replacement guidelines added activity level and hourly and daily limits on Fluid consumption. The revised recommendations to the U.S. Army’s Fluid Replacement guidelines were successful as Fluid consumption was better matched to sweat losses during hot weather military training.
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Effectiveness of revised Fluid Replacement guidelines for military training in hot weather.
Aviation space and environmental medicine, 2003Co-Authors: Margaret A. Kolka, Scott J. Montain, William A. Latzka, William P. Corr, Karen K O'brien, Michael N. SawkaAbstract:BACKGROUND This study compared the revised U.S. Army Fluid Replacement guidelines (REV) with the old guidelines (OLD) on daily changes in serum sodium concentration (Na+) and body mass (BM) during Basic Combat Training at Fort Benning, GA during two successive summers. METHODS Recruits (n = 550; OLD = 277, REV = 273) were evaluated before and after 8-12 h of outdoor military combat training in hot weather. The WBGT (mean +/- SD) averaged 26.6 +/- 1.7 degrees C for OLD and 27.4 +/- 0.9 degrees C for REV (NS). RESULTS Serum Na+ decreased from 137.5 +/- 1.6 mEq x L(-1) to 137.0 +/- 2.1 mEq x L(-1) after outdoor military training in OLD (p < 0.05). Twenty-two recruits (8%) had serum sodium fall to below 135 mEq x L(-1) during OLD. Serum Na+ increased from 139.0 +/- 1.7 mEq x L(-1) to 139.4 +/- 2.1 mEq x L(-1) after outdoor military training in REV (p < 0.05). Only two recruits (1%) had serum Na+ fall to below 135 mEq x L(-1) during REV. BM increased an average of 1.3 +/- 1.4 kg (p < 0.05) in OLD and an average of 0.4 +/- 1.7 kg in REV (p < 0.05). CONCLUSIONS The revised guidelines effectively reversed the decrease in serum sodium, reduced the increase in body mass, maintained hydration and minimized overdrinking during hot weather military training compared with the old Fluid Replacement guidelines.
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Fluid Replacement recommendations for training in hot weather.
Military medicine, 1999Co-Authors: Scott J. Montain, William A. Latzka, Michael N. SawkaAbstract:The U.S. Army's Fluid Replacement guidelines emphasize Fluid Replacement during hot weather training to prevent degradation of performance and minimize the risk of heat injury. Little consideration has been given, however, to possible overhydration and development of water intoxication. Sufficient epidemiological evidence is available to demonstrate an increasing incidence of water intoxication during military training. This article summarizes the development and validation of revised Fluid Replacement guidelines for hot weather training. The end product is an easy-to-read table that provides the user with the appropriate hourly work time and Fluid intake to support work during hot weather training. The guidelines include the range of hot weather conditions likely to be encountered during military training and cover a broad range of military activities. It is expected that the revised guidelines will sustain hydration and minimize the number of heat injuries during military training while protecting the soldier from becoming sick from overdrinking.
W. M. Sherman - One of the best experts on this subject based on the ideXlab platform.
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ACSM Position Stand: Exercise and Fluid Replacement
Medicine & Science in Sports & Exercise, 1996Co-Authors: Victor A. Convertino, Michael N. Sawka, Lawrence E. Armstrong, Edward F. Coyle, Gary W. Mack, Leo C. Senay, W. M. ShermanAbstract:SUMMARYIt is the position of the American College of Sports Medicine that adequate Fluid Replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a
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American College of Sports Medicine position stand. Exercise and Fluid Replacement.
Medicine and science in sports and exercise, 1996Co-Authors: Victor A. Convertino, Edward F. Coyle, Gary W. Mack, Leo C. Senay, L E Armstrong, M N Sawka, W. M. ShermanAbstract:It is the position of the American College of Sports Medicine that adequate Fluid Replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a comprehensive review and interpretation of scientific literature concerning the influence of Fluid Replacement on exercise performance and the risk of thermal injury associated with dehydration and hyperthermia. Based on available evidence, the American College of Sports Medicine makes the following general recommendations on the amount and composition of Fluid that should be ingested in preparation for, during, and after exercise or athletic competition: 1) It is recommended that individuals consume a nutritionally balanced diet and drink adequate Fluids during the 24-hr period before an event, especially during the period that includes the meal prior to exercise, to promote proper hydration before exercise or competition. 2) It is recommended that individuals drink about 500 ml (about 17 ounces) of Fluid about 2 h before exercise to promote adequate hydration and allow time for excretion of excess ingested water. 3) During exercise, athletes should start drinking early and at regular intervals in an attempt to consume Fluids at a rate sufficient to replace all the water lost through sweating (i.e., body weight loss), or consume the maximal amount that can be tolerated. 4) It is recommended that ingested Fluids be cooler than ambient temperature [between 15 degrees and 22 degrees C (59 degrees and 72 degrees F])] and flavored to enhance palatability and promote Fluid Replacement. Fluids should be readily available and served in containers that allow adequate volumes to be ingested with ease and with minimal interruption of exercise. 5) Addition of proper amounts of carbohydrates and/or electrolytes to a Fluid Replacement solution is recommended for exercise events of duration greater than 1 h since it does not significantly impair water delivery to the body and may enhance performance. During exercise lasting less than 1 h, there is little evidence of physiological or physical performance differences between consuming a carbohydrate-electrolyte drink and plain water. 6) During intense exercise lasting longer than 1 h, it is recommended that carbohydrates be ingested at a rate of 30-60 g.h(-1) to maintain oxidation of carbohydrates and delay fatigue. This rate of carbohydrate intake can be achieved without compromising Fluid delivery by drinking 600-1200 ml.h(-1) of solutions containing 4%-8% carbohydrates (g.100 ml(-1)). The carbohydrates can be sugars (glucose or sucrose) or starch (e.g., maltodextrin). 7) Inclusion of sodium (0.5-0.7 g.1(-1) of water) in the rehydration solution ingested during exercise lasting longer than 1 h is recommended since it may be advantageous in enhancing palatability, promoting Fluid retention, and possibly preventing hyponatremia in certain individuals who drink excessive quantities of Fluid. There is little physiological basis for the presence of sodium in n oral rehydration solution for enhancing intestinal water absorption as long as sodium is sufficiently available from the previous meal.
Victor A. Convertino - One of the best experts on this subject based on the ideXlab platform.
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ACSM Position Stand: Exercise and Fluid Replacement
Medicine & Science in Sports & Exercise, 1996Co-Authors: Victor A. Convertino, Michael N. Sawka, Lawrence E. Armstrong, Edward F. Coyle, Gary W. Mack, Leo C. Senay, W. M. ShermanAbstract:SUMMARYIt is the position of the American College of Sports Medicine that adequate Fluid Replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a
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American College of Sports Medicine position stand. Exercise and Fluid Replacement.
Medicine and science in sports and exercise, 1996Co-Authors: Victor A. Convertino, Edward F. Coyle, Gary W. Mack, Leo C. Senay, L E Armstrong, M N Sawka, W. M. ShermanAbstract:It is the position of the American College of Sports Medicine that adequate Fluid Replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a comprehensive review and interpretation of scientific literature concerning the influence of Fluid Replacement on exercise performance and the risk of thermal injury associated with dehydration and hyperthermia. Based on available evidence, the American College of Sports Medicine makes the following general recommendations on the amount and composition of Fluid that should be ingested in preparation for, during, and after exercise or athletic competition: 1) It is recommended that individuals consume a nutritionally balanced diet and drink adequate Fluids during the 24-hr period before an event, especially during the period that includes the meal prior to exercise, to promote proper hydration before exercise or competition. 2) It is recommended that individuals drink about 500 ml (about 17 ounces) of Fluid about 2 h before exercise to promote adequate hydration and allow time for excretion of excess ingested water. 3) During exercise, athletes should start drinking early and at regular intervals in an attempt to consume Fluids at a rate sufficient to replace all the water lost through sweating (i.e., body weight loss), or consume the maximal amount that can be tolerated. 4) It is recommended that ingested Fluids be cooler than ambient temperature [between 15 degrees and 22 degrees C (59 degrees and 72 degrees F])] and flavored to enhance palatability and promote Fluid Replacement. Fluids should be readily available and served in containers that allow adequate volumes to be ingested with ease and with minimal interruption of exercise. 5) Addition of proper amounts of carbohydrates and/or electrolytes to a Fluid Replacement solution is recommended for exercise events of duration greater than 1 h since it does not significantly impair water delivery to the body and may enhance performance. During exercise lasting less than 1 h, there is little evidence of physiological or physical performance differences between consuming a carbohydrate-electrolyte drink and plain water. 6) During intense exercise lasting longer than 1 h, it is recommended that carbohydrates be ingested at a rate of 30-60 g.h(-1) to maintain oxidation of carbohydrates and delay fatigue. This rate of carbohydrate intake can be achieved without compromising Fluid delivery by drinking 600-1200 ml.h(-1) of solutions containing 4%-8% carbohydrates (g.100 ml(-1)). The carbohydrates can be sugars (glucose or sucrose) or starch (e.g., maltodextrin). 7) Inclusion of sodium (0.5-0.7 g.1(-1) of water) in the rehydration solution ingested during exercise lasting longer than 1 h is recommended since it may be advantageous in enhancing palatability, promoting Fluid retention, and possibly preventing hyponatremia in certain individuals who drink excessive quantities of Fluid. There is little physiological basis for the presence of sodium in n oral rehydration solution for enhancing intestinal water absorption as long as sodium is sufficiently available from the previous meal.
Edward F. Coyle - One of the best experts on this subject based on the ideXlab platform.
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ACSM Position Stand: Exercise and Fluid Replacement
Medicine & Science in Sports & Exercise, 1996Co-Authors: Victor A. Convertino, Michael N. Sawka, Lawrence E. Armstrong, Edward F. Coyle, Gary W. Mack, Leo C. Senay, W. M. ShermanAbstract:SUMMARYIt is the position of the American College of Sports Medicine that adequate Fluid Replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a
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American College of Sports Medicine position stand. Exercise and Fluid Replacement.
Medicine and science in sports and exercise, 1996Co-Authors: Victor A. Convertino, Edward F. Coyle, Gary W. Mack, Leo C. Senay, L E Armstrong, M N Sawka, W. M. ShermanAbstract:It is the position of the American College of Sports Medicine that adequate Fluid Replacement helps maintain hydration and, therefore, promotes the health, safety, and optimal physical performance of individuals participating in regular physical activity. This position statement is based on a comprehensive review and interpretation of scientific literature concerning the influence of Fluid Replacement on exercise performance and the risk of thermal injury associated with dehydration and hyperthermia. Based on available evidence, the American College of Sports Medicine makes the following general recommendations on the amount and composition of Fluid that should be ingested in preparation for, during, and after exercise or athletic competition: 1) It is recommended that individuals consume a nutritionally balanced diet and drink adequate Fluids during the 24-hr period before an event, especially during the period that includes the meal prior to exercise, to promote proper hydration before exercise or competition. 2) It is recommended that individuals drink about 500 ml (about 17 ounces) of Fluid about 2 h before exercise to promote adequate hydration and allow time for excretion of excess ingested water. 3) During exercise, athletes should start drinking early and at regular intervals in an attempt to consume Fluids at a rate sufficient to replace all the water lost through sweating (i.e., body weight loss), or consume the maximal amount that can be tolerated. 4) It is recommended that ingested Fluids be cooler than ambient temperature [between 15 degrees and 22 degrees C (59 degrees and 72 degrees F])] and flavored to enhance palatability and promote Fluid Replacement. Fluids should be readily available and served in containers that allow adequate volumes to be ingested with ease and with minimal interruption of exercise. 5) Addition of proper amounts of carbohydrates and/or electrolytes to a Fluid Replacement solution is recommended for exercise events of duration greater than 1 h since it does not significantly impair water delivery to the body and may enhance performance. During exercise lasting less than 1 h, there is little evidence of physiological or physical performance differences between consuming a carbohydrate-electrolyte drink and plain water. 6) During intense exercise lasting longer than 1 h, it is recommended that carbohydrates be ingested at a rate of 30-60 g.h(-1) to maintain oxidation of carbohydrates and delay fatigue. This rate of carbohydrate intake can be achieved without compromising Fluid delivery by drinking 600-1200 ml.h(-1) of solutions containing 4%-8% carbohydrates (g.100 ml(-1)). The carbohydrates can be sugars (glucose or sucrose) or starch (e.g., maltodextrin). 7) Inclusion of sodium (0.5-0.7 g.1(-1) of water) in the rehydration solution ingested during exercise lasting longer than 1 h is recommended since it may be advantageous in enhancing palatability, promoting Fluid retention, and possibly preventing hyponatremia in certain individuals who drink excessive quantities of Fluid. There is little physiological basis for the presence of sodium in n oral rehydration solution for enhancing intestinal water absorption as long as sodium is sufficiently available from the previous meal.
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Fluid Replacement and glucose infusion during exercise prevent cardiovascular drift
Journal of Applied Physiology, 1991Co-Authors: Marc T Hamilton, Jose Gonzalezalonso, S J Montain, Edward F. CoyleAbstract:This study examined the influence of both hydration and blood glucose concentration on cardiovascular drift during exercise. We first determined if the prevention of dehydration during exercise by full Fluid Replacement prevents the decline in stroke volume (SV) and cardiac output (CO) during prolonged exercise. On two occasions, 10 endurance-trained subjects cycled an ergometer in a 22 degrees C room for 2 h, beginning at 70 +/- 1% maximal O2 uptake (VO2max) and in a euhydrated state. During one trial, no Fluid (NF) Replacement was provided and the subject's body weight declined 2.09 +/- 0.19 kg or 2.9%. During the Fluid Replacement trial (FR), water was ingested at a rate that prevented body weight from declining after 2 h of exercise (i.e., 2.34 +/- 0.17 1/2 h). SV declined 15% and CO declined 7% during the 20- to 120-min period of the NF trial while heart rate (HR) increased 10% and O2 uptake (VO2) increased 6% (all P less than 0.05). In contrast, SV was maintained during the 20- to 120-min period of FR while HR increased 5% and thus CO actually increased 7% (all P less than 0.05). Rectal temperature, SV, and HR were similar during the 1st h of exercise during NF and FR. However, after 2 h of exercise, rectal temperature was 0.6 degree C higher (P less than 0.05) and SV and CO were 11-16% lower (P less than 0.05) during NF compared with FR.(ABSTRACT TRUNCATED AT 250 WORDS)
Scott J. Montain - One of the best experts on this subject based on the ideXlab platform.
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Fluid Replacement and performance during the marathon.
Sports Medicine, 2007Co-Authors: Samuel N Cheuvront, Scott J. Montain, Michael N. SawkaAbstract:The primary purpose of this review is to relate a universal strategy for replacing Fluids to optimise marathon performance. A secondary purpose is to examine common ‘matters of debate’ that may modify Fluid needs to include the importance of realistic convective air flow, metabolic water production and waters of association with glycogen. The metabolic demands of marathon running can result in substantial sweat losses and levels of dehydration consistent with compromised endurance performance. Recommendations are provided to individualise Fluid intakes with the goal of preventing excessive dehydration (>2% body mass) as well as weight gain. The minor importance of ‘matters of debate’ to Fluid Replacement is also discussed.
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American College of Sports Medicine position stand. Exercise and Fluid Replacement.
Medicine and science in sports and exercise, 2007Co-Authors: Michael N. Sawka, Scott J. Montain, Louise M Burke, E Randy Eichner, Ronald J Maughan, Nina S StachenfeldAbstract:This Position Stand provides guidance on Fluid Replacement to sustain appropriate hydration of individuals performing physical activity. The goal of prehydrating is to start the activity euhydrated and with normal plasma electrolyte levels. Prehydrating with beverages, in addition to normal meals and Fluid intake, should be initiated when needed at least several hours before the activity to enable Fluid absorption and allow urine output to return to normal levels. The goal of drinking during exercise is to prevent excessive (>2% body weight loss from water deficit) dehydration and excessive changes in electrolyte balance to avert compromised performance. Because there is considerable variability in sweating rates and sweat electrolyte content between individuals, customized Fluid Replacement programs are recommended. Individual sweat rates can be estimated by measuring body weight before and after exercise. During exercise, consuming beverages containing electrolytes and carbohydrates can provide benefits over water alone under certain circumstances. After exercise, the goal is to replace any Fluid electrolyte deficit. The speed with which rehydration is needed and the magnitude of Fluid electrolyte deficits will determine if an aggressive Replacement program is merited.
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Current U.S. Military Fluid Replacement Guidelines
2003Co-Authors: Margaret A. Kolka, Scott J. Montain, Michael N. Sawka, William A. Latzka, Kansas StreetAbstract:This paper presents a summary of the process to revise the U.S. Military’s Fluid Replacement Guidelines. The “old” Fluid Replacement guidelines provided recommendations for Fluid Replacement based solely on climatic conditions without consideration for energy expended (activity level) or without hourly or daily limits on Fluid consumption. The “revised” Fluid Replacement guidelines added activity level and hourly and daily limits on Fluid consumption. The revised recommendations to the U.S. Army’s Fluid Replacement guidelines were successful as Fluid consumption was better matched to sweat losses during hot weather military training.
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Effectiveness of revised Fluid Replacement guidelines for military training in hot weather.
Aviation space and environmental medicine, 2003Co-Authors: Margaret A. Kolka, Scott J. Montain, William A. Latzka, William P. Corr, Karen K O'brien, Michael N. SawkaAbstract:BACKGROUND This study compared the revised U.S. Army Fluid Replacement guidelines (REV) with the old guidelines (OLD) on daily changes in serum sodium concentration (Na+) and body mass (BM) during Basic Combat Training at Fort Benning, GA during two successive summers. METHODS Recruits (n = 550; OLD = 277, REV = 273) were evaluated before and after 8-12 h of outdoor military combat training in hot weather. The WBGT (mean +/- SD) averaged 26.6 +/- 1.7 degrees C for OLD and 27.4 +/- 0.9 degrees C for REV (NS). RESULTS Serum Na+ decreased from 137.5 +/- 1.6 mEq x L(-1) to 137.0 +/- 2.1 mEq x L(-1) after outdoor military training in OLD (p < 0.05). Twenty-two recruits (8%) had serum sodium fall to below 135 mEq x L(-1) during OLD. Serum Na+ increased from 139.0 +/- 1.7 mEq x L(-1) to 139.4 +/- 2.1 mEq x L(-1) after outdoor military training in REV (p < 0.05). Only two recruits (1%) had serum Na+ fall to below 135 mEq x L(-1) during REV. BM increased an average of 1.3 +/- 1.4 kg (p < 0.05) in OLD and an average of 0.4 +/- 1.7 kg in REV (p < 0.05). CONCLUSIONS The revised guidelines effectively reversed the decrease in serum sodium, reduced the increase in body mass, maintained hydration and minimized overdrinking during hot weather military training compared with the old Fluid Replacement guidelines.
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National athletic trainers' association position statement: Fluid Replacement for athletes.
Journal of athletic training, 2000Co-Authors: Douglas J. Casa, Scott J. Montain, Lawrence E. Armstrong, Susan K. Hillman, Ralph V. Reiff, Brent S.e. Rich, William O. Roberts, Jennifer A. StoneAbstract:Abstract Objective: To present recommendations to optimize the Fluid-Replacement practices of athletes. Background: Dehydration can compromise athletic performance and increase the risk of exertional heat injury. Athletes do not voluntarily drink sufficient water to prevent dehydration during physical activity. Drinking behavior can be modified by education, increasing accessibility, and optimizing palatability. However, excessive overdrinking should be avoided because it can also compromise physical performance and health. We provide practical recommendations regarding Fluid Replacement for athletes. Recommendations: Educate athletes regarding the risks of dehydration and overhydration on health and physical performance. Work with individual athletes to develop Fluid-Replacement practices that optimize hydration status before, during, and after competition.
