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Stuempfle KJ, Hoffman MD, Weschler LB, Rogers IR, Hew-Butler T. Race diet of finishers and non-finishers in a 100 mile (161 km) mountain footrace. J Am Coll Nutr 2012; 30:529-35. [PMID: 22331688 DOI: 10.1080/07315724.2011.10719999] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
OBJECTIVE To determine if food and fluid intake is related to completion of a 161-km ultramarathon. METHODS Sixteen consenting runners in the Western States Endurance Run participated in the study. Race diets were analyzed using Nutritionist Pro software. Both total intake and intake by race segment (3 total) were evaluated. RESULTS Six of 16 subjects completed the race (finishers) in 27.0 ± 2.3 hours (mean ± SD). Non-finishers completed 96.5 ± 20.5 km in 17.0 ± 3.9 h. Overall consumption rates of kilocalories, carbohydrate, fat, and sodium were significantly greater (P < 0.05) in finishers (4.6 ± 1.7 kcal/kg/h, 0.98 ± 0.43 g carbohydrate/kg/h, 0.06 ± 0.03 g fat/kg/h, 10.2 ± 6.0 mg sodium/kg/h) versus non-finishers (2.5 ± 1.3 kcal/kg/h, 0.56 ± 0.32 g carbohydrate/kg/h, 0.02 ± 0.02 g fat/kg/h, 5.2 ± 3.0 mg sodium/kg/h). Kilocalorie, fat, fluid, and sodium consumption rates during segment 1 (first 48 km) were significantly greater in finishers than in non-finishers. CONCLUSIONS Completion of this 161-km race was related to greater fuel, fluid, and sodium consumption rates. However, intake ranges for the finishers were large, so factors other than race diet may have contributed to the successful completion of the race.
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Affiliation(s)
- Kristin J Stuempfle
- Health Sciences Department, Gettysburg College, Gettysburg, Pennsylvania 17325, USA.
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Abstract
OBJECTIVE To explore the hydration strategies of marathon runners, their sources of information and knowledge about fluid intake in the marathon, and their understanding of exercise-associated hyponatremia (EAH). DESIGN Anonymized questionnaire. SETTING London Marathon. PARTICIPANTS Marathon race participants. MAIN OUTCOME MEASURES Responses regarding planned fluid consumption, volume to be consumed, volume of water and sports drink bottles, and the number of stations from which planning to take a drink. In addition, sources of information about appropriate drinking and understanding of hyponatremia. RESULTS In total, 93.1% of the runners had read or been told about drinking fluids on marathon day and 95.8% of competitors had a plan regarding fluid intake. However, 12% planned to drink a volume large enough to put them at higher risk of EAH. Only 21.7% knew the volumes of water and sports drink bottles available on the course; 20.7% were planning to take a drink from all 24 water stations. Only 25.3% planned to drink according to thirst. Although 68.0% of the runners had heard of hyponatremia or low sodium levels, only 35.5% had a basic understanding of its cause and effects. CONCLUSIONS Marathon runners lack knowledge about appropriate fluid intake to prevent hyponatremia on race day. Twelve percent reported drinking strategies that put them at risk of EAH. Effective educational interventions are still necessary to prevent overdrinking during marathons.
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Winger J. Sodium replacement and plasma sodium drop during exercise in the heat when fluid intake matches fluid loss. J Athl Train 2011; 45:547; author reply 548. [PMID: 21062176 DOI: 10.4085/1062-6050-45.6.547] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Changes in total body water content during running races of 21.1 km and 56 km in athletes drinking ad libitum. Clin J Sport Med 2011; 21:218-25. [PMID: 21427566 DOI: 10.1097/jsm.0b013e31820eb8d7] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To measure changes in body mass (BM), total body water (TBW), fluid intake, and blood biochemistry in athletes during 21.1-km and 56-km foot races. DESIGN Observational study. SETTING 2009 Two Oceans Marathon, South Africa. PARTICIPANTS Twenty-one (21.1 km) and 12 (56 km) participants were advised to drink according to thirst or their own race drink plan (ad libitum). MAIN OUTCOME MEASURES Body mass, TBW, plasma osmolality, plasma sodium (p[Na]), and plasma total protein ([TP]) concentrations were measured before and after race. Fluid intake was recorded from recall after race. RESULTS Significant BM loss occurred in both races (21.1 km; -1.4 ± 0.6 kg; P < 0.000 and 56 km; -2.5 ± 1.1 kg; P < 0.000). Total body water was reduced in the 56-km race (-1.4 ± 1.1 kg; P < 0.001). A negative linear relationship was found between percentage change (%Δ) in TBW and %Δ in BM in the 56-km runners (r = 0.6; P < 0.01). Plasma osmolality and [TP] increased significantly in the 56-km runners (6.8 ± 8.2 mOsm/kg H2O; P < 0.05 and 5.4 ± 4.4 g/L; P < 0.01, respectively), but all other biochemical measures were within the normal range. CONCLUSIONS Although TBW decreased in the 56-km race and was maintained in the 21.1-km race, the change in TBW over both races was less than the BM, suggesting that not all BM lost during endurance exercise is a result purely of an equivalent reduction in TBW. These findings support the interpretation that the body primarily defends p[Na] and not BM during exercise and that a reduction in BM can occur without an equivalent reduction in TBW during prolonged exercise. Furthermore, these data support that drinking without controlling for BM loss may allow athletes to complete these events.
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In a hot–dry environment racewalking increases the risk of hyperthermia in comparison to when running at a similar velocity. Eur J Appl Physiol 2010; 111:1073-80. [DOI: 10.1007/s00421-010-1733-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/08/2010] [Indexed: 11/26/2022]
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Abstract
Exercise is making a resurgence in many countries, given its benefits for fitness as well as prevention of obesity. This trend has spawned many supplements that purport to aid performance, muscle growth, and recovery. Initially, sports drinks were developed to provide electrolyte and carbohydrate replacement. Subsequently, energy beverages (EBs) containing stimulants and additives have appeared in most gyms and grocery stores and are being used increasingly by "weekend warriors" and those seeking an edge in an endurance event. Long-term exposure to the various components of EBs may result in significant alterations in the cardiovascular system, and the safety of EBs has not been fully established. For this review, we searched the MEDLINE and EMBASE databases from 1976 through May 2010, using the following keywords: energy beverage, energy drink, power drink, exercise, caffeine, red bull, bitter orange, glucose, ginseng, guarana, and taurine. Evidence regarding the effects of EBs is summarized, and practical recommendations are made to help in answering the patient who asks, "Is it safe for me to drink an energy beverage when I exercise?"
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Affiliation(s)
- John P Higgins
- Division of Cardiology, Lyndon B. Johnson General Hospital, and Memorial Hermann Sports Medicine Institute, The University of Texas Medical School at Houston, Houston, TX 77026-1967, USA.
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Lee JKW. Unsubstantiated Speculation on the Lack of Fluid Intake in Increasing Heat-Related Illnesses. J Strength Cond Res 2010. [DOI: 10.1519/jsc.0b013e3181f442c5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Godek SF, Bartolozzi AR, Peduzzi C, Heinerichs S, Garvin E, Sugarman E, Burkholder R. Fluid consumption and sweating in National Football League and collegiate football players with different access to fluids during practice. J Athl Train 2010; 45:128-35. [PMID: 20210616 DOI: 10.4085/1062-6050-45.2.128] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
CONTEXT Considerable controversy regarding fluid replacement during exercise currently exists. OBJECTIVE To compare fluid turnover between National Football League (NFL) players who have constant fluid access and collegiate football players who replace fluids during water breaks in practices. DESIGN Observational study. SETTING Respective preseason training camps of 1 National Collegiate Athletic Association Division II (DII) football team and 1 NFL football team. Both morning and afternoon practices for DII players were 2.25 hours in length, and NFL players practiced for 2.25 hours in the morning and 1 hour in the afternoon. Environmental conditions did not differ. PATIENTS OR OTHER PARTICIPANTS Eight NFL players (4 linemen, 4 backs) and 8 physically matched DII players (4 linemen, 4 backs) participated. INTERVENTION(S) All players drank fluids only from their predetermined individual containers. The NFL players could consume both water and sports drinks, and the DII players could only consume water. MAIN OUTCOME MEASURE(S) We measured fluid consumption, sweat rate, total sweat loss, and percentage of sweat loss replaced. Sweat rate was calculated as change in mass adjusted for fluids consumed and urine produced. RESULTS Mean sweat rate was not different between NFL (2.1 +/- 0.25 L/h) and DII (1.8 +/- 0.15 L/h) players (F(1,12) = 2, P = .18) but was different between linemen (2.3 +/- 0.2 L/h) and backs (1.6 +/- 0.2 L/h) (t(14) = 3.14, P = .007). We found no differences between NFL and DII players in terms of percentage of weight loss (t(7) = -0.03, P = .98) or rate of fluid consumption (t(7) = -0.76, P = .47). Daily sweat loss was greater in DII (8.0 +/- 2.0 L) than in NFL (6.4 +/- 2.1 L) players (t(7) = -3, P = .02), and fluid consumed was also greater in DII (5.0 +/- 1.5 L) than in NFL (4.0 +/- 1.1 L) players (t(7) = -2.8, P = .026). We found a correlation between sweat loss and fluids consumed (r = 0.79, P < .001). CONCLUSIONS During preseason practices, the DII players drinking water at water breaks replaced the same volume of fluid (66% of weight lost) as NFL players with constant access to both water and sports drinks.
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Abstract
Exercise-associated hyponatremia (EAH) is hyponatremia that occurs <or= 24 hours after prolonged physical activity. It is a potentially serious complication of marathons, triathlons, and ultradistance events, and can occur in hot and cold environments. Clear evidence indicates that EAH is a dilutional hyponatremia caused by excessive fluid consumption and the inappropriate release of arginine vasopressin. Cerebral and pulmonary edema can cause serious signs and symptoms, including altered mental status, respiratory distress, seizures, coma, and death. Rapid diagnosis and urgent treatment with hypertonic saline is necessary to prevent severe complications or death. Prevention is based on educating athletes to avoid excessive drinking before, during, and after exercise.
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Affiliation(s)
- Kristin J Stuempfle
- Department of Health Sciences, Gettysburg College, Gettysburg, PA 17325, USA.
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Thermoregulation, pacing and fluid balance during mass participation distance running in a warm and humid environment. Eur J Appl Physiol 2010; 109:887-98. [DOI: 10.1007/s00421-010-1405-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2010] [Indexed: 10/19/2022]
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Bike Transalp 2008: liquid intake and its effect on the body's fluid homeostasis in the course of a multistage, cross-country, MTB marathon race in the central Alps. Clin J Sport Med 2010; 20:47-52. [PMID: 20051734 DOI: 10.1097/jsm.0b013e3181c9673f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVES To investigate the drinking behavior of the participants in a multi-day mountain bike (MTB) cross-country competition, to monitor its effect on the body's fluid compartments and body mass, and to evaluate the prevalence of exercise-associated dysnatremia. DESIGN Descriptive field study. SETTING The Jeantex Bike Transalp Competition 2008 (8 stages; 665.40 km; 21 691 m height). PARTICIPANTS Twenty-five male, amateur MTB cyclists. INDEPENDENT VARIABLES Reported fluid intake during the race, air temperature. MAIN OUTCOME MEASURES Changes in body mass and body composition from pre to post race and throughout the competition week, serum sodium concentration at finish line of stages 5 and 6. RESULTS Mean (+ or - SD) hourly fluid intake during the race correlated with air temperature (r = 0.868, P < .05) and ranged between 494 + or - 191 mL/h and 754 + or - 254 mL/h. In absence of exercise-induced hyponatremia (EAH) cases, we report 5 and 4 cases of asymptomatic post-race hypernatremia, on days 5 and 6, respectively. When related to race time and body mass, the liquid intake during the race (in mL x kg(-1) x h(-1)) correlated with post-race serum sodium concentration (stage 5: r = -0.463, P < .05, n = 24; stage 6: r = -0.589, P < .01, n = 23); no correlation was found between the change in body mass from pre to post race and serum sodium concentration at finish line. CONCLUSIONS Ad libitum fluid consumption during competition was spontaneously adjusted to the unsettled weather conditions in the course of the 2008 "Bike Transalp." The inverse linear relationship between hourly fluid intake and post-race serum sodium concentrations suggests underdrinking to be one contributing factor to the high reported incidence of hypernatremia in the absence of EAH. Experimental studies are requested to confirm this hypothesis and to further examine the pathogenesis of exercise-associated dysnatremia. In this setting, body mass monitoring was not an accurate instrument to control body fluid homeostasis.
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Fluid Intake and Changes in Blood Biochemistry, Running Speed and Body Mass During an 80 km Mountain Trail Race. ACTA ACUST UNITED AC 2009. [DOI: 10.2478/v10036-009-0017-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Godek SF, Bartolozzi AR. Changes in Blood Electrolytes and Plasma Volume in National Football League Players During Preseason Training Camp. ACTA ACUST UNITED AC 2009. [DOI: 10.3928/19425864-20091019-03] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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65
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Abstract
UNLABELLED Disorders of serum sodium concentration occur commonly in athletes participating in endurance sports. While hypernatremia is the most commonly seen disorder, hyponatremia can occur in 2% to 7% of participants. Hyponatremia is due to a combination of excessive water or hypotonic fluid intake as well as high levels of arginine vasopressin (or anti diuretic hormone), which limits the ability of the kidney to excrete water. Most of these cases are associated with either no or minimal side effects and do not require specific therapy other than close monitoring and fluid restriction. However, a small number of athletes may present with severe and life-threatening hyponatremia associated with cerebral edema and possibly noncardiogenic pulmonary edema. Rapid diagnosis and appropriate therapy of these symptomatic athletes with hypertonic saline is required to prevent severe complications or death. The ability to have rapid on-site measurement of serum sodium concentration greatly facilitates accurate diagnosis and therapy. Prevention is based on widespread education regarding the risks of overhydration and judicious intake of fluids during endurance events. KEYWORDS hyponatremia; cerebral edema; therapy; hypertonic saline.
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Affiliation(s)
- Mitchell H Rosner
- Department of Medicine, University of Virginia Health System, Charlottesville, VA, 22908, USA.
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Lee JKW, Lim CL. Important Considerations for Recommending Hydration Studies. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2008. [DOI: 10.47102/annals-acadmedsg.v37n11p986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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Hill RJ, Bluck LJC, Davies PSW. The hydration ability of three commercially available sports drinks and water. J Sci Med Sport 2008; 11:116-23. [PMID: 17544328 DOI: 10.1016/j.jsams.2006.12.117] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2006] [Revised: 12/14/2006] [Accepted: 12/15/2006] [Indexed: 11/18/2022]
Abstract
This paper compares the hydration ability of three commercially-available sports drinks with water under conditions of rest and exercise, using a deuterium dilution technique. For the rest group, 0.05g/kg of body weight of deuterium, contained in gelatine capsules, was ingested with one of the test solutions and saliva samples were collected every five minutes for an hour while the subject remained seated. The deuterium was administered as above for the exercise group but sample collection was during one hour of exercise on a treadmill at 55% of the subject's maximum heart rate. The enrichment data for each subject were mathematically modelled to describe the kinetics of hydration and the parameters obtained were compared across drinks using a basic Anova. At rest, significant differences were found for t(1), t(1/2), and the percent of drink absorbed at t(1). The differences between drinks were not significant for t(2) or the maximum absorption rate. For the exercise group, the only significant difference was found between water and the sports drinks at t(1). Therefore, we conclude that labelling with a deuterium tracer is a good measure of the relative rate ingested fluids are absorbed by the body. Because of the lack of differences found at t(2), which is indicative of the 100% absorption time, both at rest and during exercise, it may be speculated that, compared to water, the sports drinks studied in this paper did not hydrate the body at a faster rate.
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Affiliation(s)
- Rebecca J Hill
- Department of Paediatrics and Child Health, University of Queensland, Queensland, Australia.
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Abstract
Maximal performance during competition is the drive many competitors use to train harder. However, there are several variables that contribute to impair a competitor's performance. These variables work by altering the homeostatic mechanisms within the body. Once homeostasis is altered the competitor's body is no longer optimized to face the stresses of the athletic competition. The environment works as an all encompassing variable that will affect sweat rate. During increased environmental heat strain, one must adjust for critical variables, such as temperature regulation, hydration status, and electrolyte levels, as they can contribute to impaired performance. Acclimatization through training and competition will reduce or slow down the effects of these stress factors. Ever evolving recommendations are produced to aid competitors in maintaining homeostasis. Despite all the generic recommendations that are made, however, every athlete needs to individualize their training and competition regimens to optimize personal performance.
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Affiliation(s)
- Joseph A. Rothenberg
- Physical Medicine & Rehabilitation, New York Presbyterian Hospital, New York, NY USA
| | - André Panagos
- Physical Medicine & Rehabilitation, New York Presbyterian Hospital, New York, NY USA
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Anglem N, Lucas SJ, Rose EA, Cotter JD. Mood, Illness and Injury Responses and Recovery with Adventure Racing. Wilderness Environ Med 2008; 19:30-8. [DOI: 10.1580/07-weme-or-091.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Statement of the Second International Exercise-Associated Hyponatremia Consensus Development Conference, New Zealand, 2007. Clin J Sport Med 2008; 18:111-21. [PMID: 18332684 DOI: 10.1097/jsm.0b013e318168ff31] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Abstract
OBJECTIVE Describe risk factors for lower post-race [Na+] and exercise-associated hyponatremia (EAH) (serum [Na+]<135 mmol/L) during marathon running. DESIGN Prospective observational study. SETTING Houston Marathon 2000-2004. PATIENTS Ninety-six runners from EAH research projects. INTERVENTIONS Observational. MAIN OUTCOME MEASUREMENTS Pre-race and post-race measurements: serum [Na+], weight, and fluid ingestion. RESULTS Twenty-one runners (22%) met criteria for EAH, and 87% of subjects had lower post-race [Na+] compared to pre-race [Na+]. Lower post-race [Na+] and larger [Na+] decrease were related to lower pre-race [Na+], less weight loss during the race, and more fluid cups consumed. Increased fluid consumed correlated with slower finish time, male gender, and warmer temperature. Less weight loss correlated with lower pre-race weight, more fluid consumed, and slower finish time. Losing less than 0.75 kg increased the risk of becoming hyponatremic 7 fold (RR=7.0; CI 1.8 to 26.6) compared to those who lost more than 0.75 kg. Women consumed fluid at a significantly lower rate than men (P=0.04). Estimated mean fluid balance for women was positive and significantly higher than men's negative fluid balance (P<0.0001). Fluid balance became more positive as finish time increased and pre-race weight decreased. CONCLUSIONS Lighter and slower runners have more positive fluid balance. Losing>0.75 kg of body weight during a marathon is advisable in order to decrease the risk of EAH. Runners should measure their sweat rate and monitor weight changes as part of their fluid consumption plan.
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Abstract
Early human ancestors evolved hunting in the midday heat on the dry African savannah and developed favourable biological adaptations that permit prolonged running in the heat. These physiological adaptations must have included the capacity to sweat profusely to maintain a low body temperature when running for 4-6 hours in dry heat, an absence of adverse consequences from developing mild to moderate fluid deficits caused by sweat losses during the hunt, a serum osmolality based thirst mechanism and the ability to 'outrun their thirst' (to resist the deleterious psychological and other effects of severe thirst). Until the early 1970s, the guidelines for fluid ingestion during exercise were not to drink and are consistent with this interpretation. By 1996, guidelines stated, "individuals should be encouraged to consume the maximal amount of fluids during exercise that can be tolerated without gastrointestinal discomfort up to a rate equal to that lost from sweating," and this was interpreted by some as "to drink as much as tolerable." This article argues that humans are designed to drink just enough to maintain plasma osmolality, not necessarily bodyweight, both at rest and during exercise. Drinking to maintain bodyweight may impair exercise performance by inducing a weight penalty and may increase the probability of exercise-associated hyponatraemia in slow marathon runners.
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Affiliation(s)
- Timothy D Noakes
- Department of Human Biology, University of Cape Town, Sports Science Institute of South Africa, Cape Town, South Africa.
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Reid SA, King MJ. Serum biochemistry and morbidity among runners presenting for medical care after an Australian mountain ultramarathon. Clin J Sport Med 2007; 17:307-10. [PMID: 17620786 DOI: 10.1097/jsm.0b013e31804c77da] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE To determine if exercise-associated hyponatremia (EAH) was a cause of morbidity among runners requiring medical care at an Australian mountain ultramarathon. DESIGN Case series. SETTING Six Foot Track mountain ultramarathon, New South Wales, Australia, March 2006. PATIENTS Runners presenting to the medical facility. ASSESSMENT Serum biochemistry. RESULTS No cases of exercise-associated hyponatremia were identified among 9 athletes (from 775 starters) who were treated with intravenous fluid therapy. Unwell runners had a mean serum (Na) of 143 mmol/L (range 138-147 mmol/L). All runners tested had elevated serum urea and creatinine concentrations. CONCLUSION In this setting, EAH was not a significant cause of morbidity.
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Siegel AJ, Verbalis JG, Clement S, Mendelson JH, Mello NK, Adner M, Shirey T, Glowacki J, Lee-Lewandrowski E, Lewandrowski KB. Hyponatremia in marathon runners due to inappropriate arginine vasopressin secretion. Am J Med 2007; 120:461.e11-7. [PMID: 17466660 DOI: 10.1016/j.amjmed.2006.10.027] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2006] [Revised: 09/08/2006] [Accepted: 10/02/2006] [Indexed: 11/16/2022]
Abstract
PURPOSE Exercise-associated hyponatremia (EAH), as defined by a blood sodium concentration [Na+] less than 135 mmol/L, may lead to hypotonic encephalopathy with fatal cerebral edema. Understanding the pathogenetic role of antidiuresis may lead to improved strategies for prevention and treatment. METHODS Normonatremic marathon runners were tested pre- and post-race for creatine kinase, interleukin-6, cortisol, prolactin, and arginine vasopressin. Similar testing also was carried out in runners with encephalopathy caused by EAH, including 2 cases with fatal cerebral edema. RESULTS Normonatremic runners (n = 33; 2001) with a mean 3% decrease in body weight showed a 40-fold increase in interleukin-6 (66.6 +/- 11.9 pg/mL from 1.6 +/- 0.5 pg/mL, P = .001), which was significantly correlated with increases in creatine kinase (r = 0.88, P = <.0001), cortisol (r = 0.70, P = .0003), and prolactin (r = 0.67, P <.007), but not arginine vasopressin (r = 0.44, P = .07). Collapsed runners with EAH (n = 22; 2004) showed a mean blood urea nitrogen less than 15 mg/dL with measurable plasma levels of arginine vasopressin (>0.5 pg/mL) in 43% of cases. Two marathon runners with fatal cerebral edema additionally showed less than maximally dilute urines (>100 mmol/kg/H2O) and urine [Na+] greater than 25 mEq/L. CONCLUSIONS Cases of EAH fulfill the essential diagnostic criteria for the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Runners with hypotonic encephalopathy at subsequent races were treated with intravenous hypertonic (3%) saline on the basis of this paradigm, which resulted in rapid clinical improvement without adverse effects. Release of muscle-derived interleukin-6 may play a role in the nonosmotic secretion of arginine vasopressin, thereby linking rhabdomyolysis to the pathogenesis of EAH.
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