Hyponatremia in runners requiring on-site medical treatment at a single marathon

What is known about the health effects of non-steroidal anti-inflammatory drug (NSAID) use in marathon and ultraendurance running: a scoping review

This systematic scoping review aimed to understand the extent and scope of evidence on the health risks of non-steroidal anti-inflammatory drug (NSAID) use in marathon and ultraendurance running. NSAIDs are commonly consumed by runners to combat pain and inflammation; however, the health risks of consuming these drugs during marathon and ultrarunning events are currently not fully understood. Four databases (Cochrane Library, PubMed, MEDLINE and SPORTDiscus) were searched to identify articles focusing on running events of 26.2 miles or further, and they must have reported on the health risks of NSAID use. There was no restriction on the study design or the date of publication. Thirty studies were ultimately included: 4 randomised controlled trials, 1 cross-sectional study, 11 retrospective reviews, 4 case reports, 1 non-randomised control trial, and 9 prospective observational studies. The literature showed that potential health concerns of NSAID use could be split into five categories: electrolyte balance and hyponatraemia; acute kidney injury (AKI); gastrointestinal disturbances; oxidative stress, inflammation and muscle damage; other medical concerns. None of these sections had clear statistically significant links with NSAID use in ultraendurance running. However, potential links were shown, especially in AKI and electrolyte balance. This review suggests there is very limited evidence to show that NSAIDs have a negative impact on the health of ultrarunning athletes. Indications from a few non-randomised studies of a possible effect on kidney function need exploring with more high-quality research.

Exercise-Associated Hyponatremia in Marathon Runners

Exercise-associated hyponatremia (EAH) was first described as water intoxication by Noakes et al. in 1985 and has become an important topic linked to several pathological conditions. However, despite progressive research, neurological disorders and even deaths due to hyponatremic encephalopathy continue to occur. Therefore, and due to the growing popularity of exercise-associated hyponatremia, this topic is of great importance for marathon runners and all professionals involved in runners' training (e.g., coaches, medical staff, nutritionists, and trainers). The present narrative review sought to evaluate the prevalence of EAH among marathon runners and to identify associated etiological and risk factors. Furthermore, the aim was to derive preventive and therapeutic action plans for marathon runners based on current evidence. The search was conducted on PubMed, Scopus and Google Scholar using a predefined search algorithm by aggregating multiple terms (marathon run; exercise; sport; EAH; electrolyte disorder; fluid balance; dehydration; sodium concentration; hyponatremia). By this criterion, 135 articles were considered for the present study. Our results revealed that a complex interaction of different factors could cause EAH, which can be differentiated into event-related (high temperatures) and person-related (female sex) risk factors. There is variation in the reported prevalence of EAH, and two major studies indicated an incidence ranging from 7 to 15% for symptomatic and asymptomatic EAH. Athletes and coaches must be aware of EAH and its related problems and take appropriate measures for both training and competition. Coaches need to educate their athletes about the early symptoms of EAH to intervene at the earliest possible stage. In addition, individual hydration strategies need to be developed for the daily training routine, ideally in regard to sweat rate and salt losses via sweat. Future studies need to investigate the correlation between the risk factors of EAH and specific subgroups of marathon runners.

Sudden death in young athletes: Is it preventable?

Sudden death in young athletes is a rare but always dramatic condition. Unlike all other rare diseases, the estimate of its real incidence is made complex not only because of the uncertain number of correctly identified cases (numerator) but also because of the uncertain estimation of the real number of the reference population, the athletes (denominator). New elements of complexity are also emerging with regard to prevention. The current two pillars of prevention are pre-participation screening (proactive strategy) and promoting use / access to the automated external defibrillator (reactive strategy). The standardization of procedures implemented over the past two decades for pre-participation screening can now allow us to assess the impact of this approach. The result is complex to evaluate. While screening may allow the identification of conditions potentially associated with SDA, and therefore the adoption of specific treatments, in about 0.4% of screened subjects, a single study investigated the yield in terms of mortality showing a positive predictive value of 4.7% with 25% sensitivity. Conversely, the reactive strategy appears considerably effective, due to the widespread use of the automated external defibrillators in sports facilities, calling for a homogeneous implementation worldwide. On a broader perspective, the vast attention devoted to SDA prevention in the world of sports represents a major driver for transfer of a reactive prevention strategy to the general population.

Effects of Sodium Intake on Health and Performance in Endurance and Ultra-Endurance Sports

The majority of reviews on sports nutrition issues focus on macronutrients, often omitting or paying less attention to substances such as sodium. Through the literature, it is clear that there are no reviews that focus entirely on the effects of sodium and in particular on endurance sports. Sodium intake, both at high and low doses, has been found to be associated with health and performance issues in athletes. Besides, there have been theories that an electrolyte imbalance, specifically sodium, contributes to the development of muscle cramps (EAMC) and hyponatremia (EAH). For this reason, it is necessary to create this systematic review, in order to report extensively on the role of sodium consumption in the population and more specifically in endurance and ultra-endurance athletes, the relationship between the amount consumed and the occurrence of pathological disorders, the usefulness of simultaneous hydration and whether a disturbance of this substance leads to EAH and EAMC. As a method of data collection, this study focused on exploring literature from 2000–2021. The search was conducted through the research engines PubMed and Scopus. In order to reduce the health and performance effects in endurance athletes, simultaneous emphasis should be placed on both sodium and fluid intake.

Burden of Injury and Illness in the Road Race Medical Tent: A Narrative Review

OBJECTIVE

To summarize the literature relating to prehospital care at 5 km through marathon distance road races and present the epidemiology of common medical encounters, significant medical complications, and medical outcomes.

DATA SOURCES

We searched PubMed and Google Scholar for the published literature pertaining to road race medical tent encounters at 5 km through marathon distance road races from 2000 to 2018. We included English-language, original articles reporting on injury and illness incidence.

MAIN RESULTS

Standard medical encounter definitions have recently been formulated in response to the previous lack of uniform definitions. The incidence of medical complications at road races may be influenced by environmental conditions and race distance. Minor and moderate medical encounters, such as dermatologic injuries, musculoskeletal injuries, and exercise-associated collapse, are common. Serious and life-threatening medical complications, including exertional heat stroke, exercise-associated hyponatremia, and cardiac arrest, are less frequent. Fatalities are also rare, with rates of 0.3 to 5 per 100 000 participants reported at marathons. The ratio of hospital transports to medical encounters is low.

CONCLUSIONS

On-site medical services play a key role in the safety of both runners and the community. Future research and care initiatives in this field should focus on optimizing treatment protocols, promoting injury prevention efforts and reducing host community costs.

Exertional Heat Stroke at the Boston Marathon: Demographics and the Environment

PURPOSE

This study aimed to assess associations between exertional heat stroke (EHS) and sex, age, prior performance, and environmental conditions, and report on resources needed for EHS cases at the Boston Marathon.

METHODS

We analyzed participant characteristics, environmental data, and EHS medical encounters during the 2015-2019 Boston Marathon races.

RESULTS

Among 136,161 starters, there was an incidence of 3.7 EHS cases per 10,000 starters (95% confidence interval, 2.8-4.9), representing 0.5% of all medical encounters. There were significant associations between sex and age (P < 0.0001), sex and start wave (P < 0.0001), and age group and start wave (P < 0.0001). Sex was not significantly associated with increased EHS incidence; however, age younger than 30 yr and assignment to the first two start waves were. All cases occurred at races with average wet bulb globe temperatures of 17°C-20°C. There was a linear correlation between EHS incidence and greater increases in wet bulb globe temperature from start to peak (R2 = 0.7688). A majority of cases (37; 72.5%) were race finishers; nonfinishers all presented after mile 18. Most were triaged 3-4 h after starting, and all were treated with ice water immersion. Treatment times were prolonged (mean (SD), 78.1 (47.5) min; range, 15-190 min); 29.4% (15 cases) developed posttreatment hypothermia, and 35.3% (18 cases) were given intravenous fluids. Most (31 cases; 64.6%) were discharged directly, although 16 cases (33.3%) required hospital transport. There were no fatalities.

CONCLUSIONS

Younger and faster runners are at higher risk for EHS at the Boston Marathon. Greater increases in heat stress from start to peak during a marathon may exacerbate risk. EHS encounters comprise a small percentage of race-day medical encounters but require extensive resources and warrant risk mitigation efforts.

Exercise-Associated Hyponatremia during the Olympus Marathon Ultra-Endurance Trail Run

Research on hyponatremia during mountain marathons is scarce. The present study aimed to investigate the prevalence of exercise-associated hyponatremia during a 44-km trail running race that reached an altitude of 2780 m (Olympus Marathon). Sixty-two runners (five women) who completed the race participated in the study (age: 34.4 ± 8.6 years; height: 1.77 ± 0.06 m; and weight: 75.3 ± 10.0 kg). Anthropometric characteristics, blood, and urine samples were collected pre- and post-race. Food and fluid intake were recorded at each checkpoint. Due to race regulations, the runners could not carry any additional food and fluids besides the ones provided at specific checkpoints. Five runners (8%) exhibited asymptomatic hyponatremia (serum sodium <135 mmol∙L^-1). Serum sodium in the hyponatremic runners decreased from 138.4 ± 0.9 (pre) to 131.4 ± 5.0 mmol∙L^-1 (post), p < 0.05. Plasma osmolality increased only in the eunatremic runners (pre: 290 ± 3; post: 295 ± 6 mmol∙kg^-1; p < 0.05). Plasma volume decreased more in the hyponatremic compared to eunatremic runners (-4.4 ± 2.0 vs. -3.2 ± 1.4%, p < 0.05). Lastly, dietary sodium intake was lower in the hyponatremic runners compared to eunatremic (789 ± 813 vs. 906 ± 672 mg; p < 0.05). The incidence of hyponatremia among the athletes was relatively low, possibly due to race conditions.

Physiological and Pathophysiological Responses to Ultramarathon Running in Non-elite Runners

Ultramarathon running represents a major physical challenge even for elite athletes. Runners wellbeing may be challenged by fluid and electrolyte disturbances, hemolysis and skeletal muscle damage, decline in hepatic function and kidney injury. We hypothesized that these effects may even be exacerbated in non-elite runners. Physiological, hematological and biochemical parameters of ten males (26–45 years, weekly training time 8.5 h), participating in a mountain ultramarathon (67 km; approximately 4,500 m of total ascent), were determined before (PRE), immediately after finishing the ultramarathon (POST), and 24 h after the individual finish (REC). Race times of the 8 finishers (2 drop-outs due to hot ambient temperature) varied between 10.4 and 16.1 h, which almost represents the range of the entire starter field (8.82 h–17.47 h). The following changes in mean values of selected markers for skeletal muscle damage and kidney injury were observed from PRE to POST: creatine kinase (CK) + 1289%, lactate dehydrogenase (LDH) + 87%, serum creatinine (CR) + 72%, blood urea nitrogen (BUN) + 96%, and estimated glomerular filtration rate (eGFR) – 45%. Values of CK + 1447%, LDH + 56%, and BUN + 71% remained elevated at REC. White blood cells were increased (+ 137%) only POST. In conclusion, CK and LDH levels and leucocytosis may be considered to be relatively harmless “side-effects” of prolonged running in this group of male subjects with rather moderate ultramarathon experience and training status. However, acute kidney injury may become clinically relevant in this population under the certain conditions, which should be considered by responsible race managers and medical advisors.

Exercise-Associated Hyponatremia in Endurance and Ultra-Endurance Performance-Aspects of Sex, Race Location, Ambient Temperature, Sports Discipline, and Length of Performance: A Narrative Review

Exercise-associated hyponatremia (EAH) is defined as a plasma sodium concentration of <135 mmol/L during or after endurance and ultra-endurance performance and was first described by Timothy Noakes when observed in ultra-marathoners competing in the Comrades Marathon in South Africa in the mid-1980s. It is well-established that a decrease in plasma sodium concentration <135 mmol/L occurs with excessive fluid intake. Clinically, a mild hyponatremia will lead to no or very unspecific symptoms. A pronounced hyponatremia (<120 mmol/L) will lead to central nervous symptoms due to cerebral edema, and respiratory failure can lead to death when plasma sodium concentration reaches values of <110-115 mmol/L. The objective of this narrative review is to present new findings about the aspects of sex, race location, sports discipline, and length of performance. The prevalence of EAH depends on the duration of an endurance performance (i.e., low in marathon running, high to very high in ultra-marathon running), the sports discipline (i.e., rather rare in cycling, more frequent in running and triathlon, and very frequent in swimming), sex (i.e., increased in women with several reported deaths), the ambient temperature (i.e., very high in hot temperatures) and the country where competition takes place (i.e., very common in the USA, very little in Europe, practically never in Africa, Asia, and Oceania). A possible explanation for the increased prevalence of EAH in women could be the so-called Varon-Ayus syndrome with severe hyponatremia, lung and cerebral edema, which was first observed in marathon runners. Regarding the race location, races in Europe seemed to be held under rather moderate conditions whereas races held in the USA were often performed under thermally stressing conditions (i.e., greater heat or greater cold).

[Exercise-Associated Hyponatremia in Endurance Performance]

Exercise-Associated Hyponatremia in Endurance Performance Abstract. Exercise-associated hyponatremia is defined as a plasma sodium concentration of <135 mmol/l and was first described by Timothy Noakes at the Comrades Marathon in South Africa in the mid-1980s. A decrease in plasma sodium <135 mmol/l occurs with excessive fluid intake. Risk factors include long to very long endurance performance, extreme climatic conditions, female gender and competitions in the USA. Regarding its prevalence by sport, exercise-associated hyponatraemia tends to occur while swimming and running, but rarely when cycling. While mild exercise-associated hyponatremia does not lead to clinical symptoms, severe hyponatremia due to cerebral edema can lead to neurological deficits and even death. The best prevention of exercise-associated hyponatremia is the reduction of fluid intake during exercise.

National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active

OBJECTIVE

  To present evidence-based recommendations that promote optimized fluid-maintenance practices for physically active individuals.

BACKGROUND

  Both a lack of adequate fluid replacement (hypohydration) and excessive intake (hyperhydration) can compromise athletic performance and increase health risks. Athletes need access to water to prevent hypohydration during physical activity but must be aware of the risks of overdrinking and hyponatremia. Drinking behavior can be modified by education, accessibility, experience, and palatability. This statement updates practical recommendations regarding fluid-replacement strategies for physically active individuals.

RECOMMENDATIONS

  Educate physically active people regarding the benefits of fluid replacement to promote performance and safety and the potential risks of both hypohydration and hyperhydration on health and physical performance. Quantify sweat rates for physically active individuals during exercise in various environments. Work with individuals to develop fluid-replacement practices that promote sufficient but not excessive hydration before, during, and after physical activity.

Effects of a 24-h naproxen dose on hydration and electrolyte measures during moderate-intensity cycling in the heat

Few controlled laboratory studies have examined the negative effects non-steroidal anti-inflammatory drugs can have on fluid–electrolyte balance during exercise. Our objective was to determine whether a 24-h naproxen dose negatively affected hydration and electrolyte measures before, during, and 3 h after 90 min of cycling in a hot or ambient environment. Using a double blind, randomized and counterbalanced cross-over design, 11 volunteers (six male, five female) completed four trials, with conditions as follows: (1) placebo and ambient, (2) placebo and heat, (3) naproxen and ambient, and (4) naproxen and heat. We found no statistically significant differences among experimental conditions for any dependent measures. Though not statistically significant, mean fluid volume was higher and urine volume was lower during naproxen trials compared with placebos. Mean aggregate plasma sodium was <135 mmol/L at all time points and did not significantly change over time. Overall plasma potassium significantly increased pre- (3.9 ± 0.4) to post-exercise (4.2 ± 0.4 mmol/L, p = 0.02). In conclusion, an acute naproxen dose did not significantly alter hydration–electrolyte balance. The trend for naproxen to increase fluid volume and decrease urine volume suggests the start of fluid retention, which should concern individuals at risk for hyponatremia or with pre-existing cardiovascular conditions.

Exercise-Associated Hyponatremia: 2017 Update

Exercise-associated hyponatremia (EAH) was initially described in the 1980s in endurance athletes, and work done since then has conclusively identified that overdrinking beyond thirst and non-osmotic arginine vasopressin release are the most common etiologic factors. In recent years, EAH has been described in a broader variety of athletic events and also has been linked to the development of rhabdomyolysis. The potential role of volume and sodium depletion in a subset of athletes has also been described. This review focuses on the most recent literature in the field of EAH and summarizes key new findings in the epidemiology, pathophysiology, treatment, and prevention of this condition.

Exertional Heat Illness: Emerging Concepts and Advances in Prehospital Care

Exertional heat illness is a classification of disease with clinical presentations that are not always diagnosed easily. Exertional heat stroke is a significant cause of death in competitive sports, and the increasing popularity of marathons races and ultra-endurance competitions will make treating many heat illnesses more common for Emergency Medical Services (EMS) providers. Although evidence is available primarily from case series and healthy volunteer studies, the consensus for treating exertional heat illness, coupled with altered mental status, is whole body rapid cooling. Cold or ice water immersion remains the most effective treatment to achieve this goal. External thermometry is unreliable in the context of heat stress and direct internal temperature measurement by rectal or esophageal probes must be used when diagnosing heat illness and during cooling. With rapid recognition and implementation of effective cooling, most patients suffering from exertional heat stroke will recover quickly and can be discharged home with instructions to rest and to avoid heat stress and exercise for a minimum of 48 hours; although, further research pertaining to return to activity is warranted.

PryorRR,RothRN,SuyamaJ,HostlerD.Exertional heat illness: emerging concepts and advances in prehospital care.Prehosp Disaster Med.2015;30(3):19.

Plasma electrolyte and hematological changes after marathon running in adolescents

PURPOSE

The objective of this research is to study plasma electrolyte and hematological changes in adolescent runners completing a standard 42.2-km marathon run.

METHODS

Fifty adolescents (30 healthy males and 20 healthy females) between ages 13 and 17 yr participated in the study. The participants had to undergo a routine physical examination including ECG records. Blood was taken before the race, immediately after the race, and 24 h after the race to determine complete blood cell count and electrolyte concentration.

RESULTS

Forty-seven runners completed the race with a mean finishing time of 4 h 57 min (range: 3 h 17 min 09 s to 6 h 14 min). None of the participants experienced an adverse medical event during or after the race. Only slight changes in plasma electrolytes without any cases of hyper- or hyponatremia and a marked increase in white blood cell count were demonstrated immediately after the race. At this time, the hemoglobin concentration and hematocrit were decreased (P < 0.05), indicating an approximately 11% increase in plasma volume. Some of these changes were still present 24 h postrace. No differences were observed between sexes.

CONCLUSIONS

This is the first study evaluating plasma electrolyte and hematological changes in a relatively large sample of young runners completing a standard marathon. The presented findings indicate that well-trained and educated adolescent marathon runners are not at risk to develop clinically significant electrolyte or hematological changes.

Prevalence of hyponatremia, renal dysfunction, and other electrolyte abnormalities among runners before and after completing a marathon or half marathon

Background:

Prior reports on metabolic derangements observed in distance running frequently have small sample sizes, lack prerace laboratory measures, and report sodium as the sole measure.

Hypothesis:

Metabolic abnormalities—hyponatremia, hypokalemia, renal dysfunction, hemoconcentration—are frequent after completing a full or half marathon. Clinically significant changes occur in these laboratory values after race completion.

Study Design:

Observational, cross-sectional study.

Methods:

Consenting marathon and half marathon racers completed a survey as well as finger stick blood sampling on race day of the National Marathon to Fight Breast Cancer (Jacksonville, Florida, February 2008). Parallel blood measures were obtained before and after race completion (prerace, n = 161; postrace, n = 195).

Results:

The prevalence of prerace and postrace hyponatremia was 8 of 161 (5.0%) and 16 of 195 (8.2%), respectively. Hypokalemia was not present prerace but was present in 1 runner postrace (1 of 195). Renal dysfunction occurred prerace in 14 of 161 (8.7%) and postrace in 83 of 195 (42.6%). Among those with postrace renal dysfunction, 45.8% (38 of 83) were classified as moderate or severe. Hemoconcentration was present in 2 of 161 (1.2%) prerace and 6 of 195 (3.1%) postrace. The mean changes in laboratory values were (postrace minus prerace): sodium, 1.6 mmol/L; potassium, −0.2 mmol/L; blood urea nitrogen, 2.8 mg/dL; creatinine, 0.2 mg/dL; and hemoglobin, 0.3 g/dL for 149 pairs (except blood urea nitrogen, n = 147 pairs). Changes were significant for all comparisons (P < 0.01) except potassium (P = 0.08) and hemoglobin (P = 0.01).

Conclusions:

Metabolic abnormalities are common among endurance racers, and they may be present prerace, including hyponatremia. The clinical significance of these findings is unknown.

Clinical relevance:

It is unclear which runners are at risk for developing clinically important metabolic derangements. Participating in prolonged endurance exercise appears to be safe in the majority of racers.

Can changes in body mass and total body water accurately predict hyponatremia after a 161-km running race?

OBJECTIVE

To relate changes in body mass, total body water (TBW), extracellular fluid (ECF), and serum sodium concentration ([Na]) from a 161-km ultramarathon to finish time and incidence of hyponatremia.

DESIGN

Observational.

SETTING

: The 2008 Rio Del Lago 100-Mile (161-km) Endurance Run in Granite Bay, California.

PARTICIPANTS

Forty-five runners.

MAIN OUTCOME MEASUREMENTS

Pre-race and post-race body mass, TBW, ECF, and serum [Na].

RESULTS

Body mass and serum [Na] significantly decreased 2% to 3% (P < 0.001) from pre-race to post-race, but TBW and ECF were unchanged. Significant relationships were observed between finish time and percentage change in body mass (r = 0.36; P = 0.01), TBW (r = 0.50; P = 0.007), and ECF (r = 0.61; P = 0.003). No associations were found between post-race serum [Na] and percentage change in body mass (r = -0.04; P = 0.94) or finish time (r = 0.5; P = 0.77). Hyponatremia (serum [Na] < 135 mmol/L) was present among 51.2% of finishers. Logistic regression prediction equation including pre-race TBW and percentage changes in TBW and ECF had an 87.5% concordance with the classification of hyponatremia.

CONCLUSIONS

Hyponatremia occurred in over half of the 161-km ultramarathon finishers but was not predicted by change in body mass. The combination of pre-race TBW and percentage changes in TBW and ECF explained 87.5% of the variation in the incidence of hyponatremia.

CLINICAL SIGNIFICANCE

Exercise-associated hyponatremia can occur simultaneously with dehydration and cannot be predicted by weight checks at races.

Risk factors for exercise-associated hyponatremia in non-elite marathon runners

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.

Serum biochemistry and morbidity among runners presenting for medical care after an Australian mountain ultramarathon

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.

Exercise-associated hyponatremia, renal function, and nonsteroidal antiinflammatory drug use in an ultraendurance mountain run

OBJECTIVE

To study biochemical parameters and renal function in runners completing a 60 km mountain run and to investigate the incidence of exercise-associated hyponatremia (EAH). To assess the effects of nonselective nonsteroidal antiinflammatory medication (NSAIDs) and cyclooxygenase-2 (COX-2) selective nonsteroidal antiinflammatory medication (COXIBs) on these parameters.

DESIGN

Observational cohort study.

SETTING

Kepler Challenge 60 km mountain run, Te Anau, New Zealand, December 2003.

PARTICIPANTS

One hundred thirty-one of the 360 runners entered in the race were prospectively enrolled as volunteers on the day before the race.

MAIN OUTCOME MEASURES

Subjects were weighed at race registration the day before the race and at the finish line. Blood was taken within 5 minutes of finishing and was analyzed for serum sodium, creatinine, urea, and potassium concentrations, and hematocrit. Participants were questioned about medication use in the 24 hours before and during the race (NSAIDs, COXIBs, other medications).

RESULTS

Complete data sets were obtained on 123 runners. Five athletes were biochemically hyponatremic [(Na) 130-134 mM] and four were hypernatremic [(Na) 146-148 mM]. Hyponatremia was associated with a mean weight gain of 1.32 kg (range, -1.5 to 1.6 kg). Serum [Na] varied inversely with weight change. Estimated creatinine clearance did not vary with percent weight loss. Estimated creatinine clearance declined with increasing runner age. Sixty-five percent of runners did not use any medication, whereas 20% had used NSAIDs and 15% had taken COXIBs. There were no statistically significant differences between NSAID and COXIB users in any measured parameters or between all NSAID and COXIB users when compared with nonusers.

CONCLUSIONS

Mild asymptomatic EAH was found to occur in 4% of the volunteer ultraendurance mountain runner study group and was associated with a mean weight gain of 1.32 kg (range, -1.5 to 1.6 kg) during the race. Seven percent gained weight but remained normonatremic, suggesting other compensatory mechanisms. Hypernatremia was found in 3% and was associated with a mean weight loss. Postrace serum sodium concentration varied inversely with percent weight change. Runners using any NSAID were more likely to become hyponatremic. Estimated creatinine clearance increased with increasing age. Elevated serum creatinine concentration at the end of the race returned to normal when remeasured the week after the race. Thirty-five percent of runners were found to use NSAIDs or COXIBs. The measures of weight change and of serum sodium, potassium, urea, and creatine concentration did not differ between NSAID and COXIB users or between all nonsteroidal antiinflammatory users and nonusers.

Exercise-associated hyponatremia

Exercise-associated hyponatremia has been described after sustained physical exertion during marathons, triathlons, and other endurance athletic events. As these events have become more popular, the incidence of serious hyponatremia has increased and associated fatalities have occurred. The pathogenesis of this condition remains incompletely understood but largely depends on excessive water intake. Furthermore, hormonal (especially abnormalities in arginine vasopressin secretion) and renal abnormalities in water handling that predispose individuals to the development of severe, life-threatening hyponatremia may be present. This review focuses on the epidemiology, pathogenesis, and therapy of exercise-associated hyponatremia.

Environmental illness in athletes

This article examines environmental illness in athletes. Causes, symptoms, and treatment of heat-related illness, cold-related illness, and altitude-related illness are discussed.

Medical Concerns of Marathons

One must remember that the first marathon runner, Phidippides, collapsed and died at the finish of his race. Fortunately, death has been an infrequent occurrence in modern day marathons. However, the physical exertion required to complete a marathon coupled with exposure to often harsh environmental conditions and an increase in the number of novice participants makes injuries inevitable. The medical team's main goal is to implement strategies to prevent serious injury and illness through pre-event planning, race day preparedness, and postevent evaluations. The three general categories of injuries encountered with marathon participation include medical conditions, musculoskeletal injuries, and dermatologic complaints. The focus of this article is on the evaluation and management of the varied medical concerns encountered on race day along with the essentials in prerace planning and preparedness.

Effects of Indomethacin and Celecoxib on Renal Function in Athletes

INTRODUCTION

Strenuous exercise induces a marked reduction in renal hemodynamics. Prostaglandins (PG) play an important role in maintaining renal integrity in the face of hemodynamic changes. Inhibition of cyclooxygenase (COX) and thus PG formation can further compromise renal perfusion. The role of selective COX-2 inhibition on renal hemodynamics during exercise has not been investigated.

METHODS

Twelve healthy males (22-47 yr) took part in a randomized placebo controlled study investigating the effects of nonselective COX inhibition (indomethacin) and COX-2 selective inhibition (celecoxib) on renal hemodynamics during exercise. Renal blood flow (RBF), glomerular filtration rate (GFR), and free water clearance were measured using standard clearance techniques. Each experimental session was performed at least a week apart. The medications were taken for 36 h before study with the last dose at 0700 h on the day of study. Following baseline studies, each participant exercised for 30 min at 80% of their maximal aerobic power. Renal function was monitored for 2 h post-recovery.

RESULTS

RBF and GFR fell by 40% after exercise with no significant difference between placebo, indomethacin, or celecoxib. Indomethacin (-2.43 +/- 0.95 mL x min(-1), P < 0.007) and celecoxib (-3.88 +/- 0.94 mL x min(-1), P < 0.0001) significantly reduced free water clearance compared with placebo during recovery.

CONCLUSION

This study has confirmed that selective and nonselective COX inhibition can induce significant inhibition of free water clearance, indicating that these acute changes are regulated predominantly via COX-2. Acute cerebral edema with hyponatremia has been reported after major endurance sporting events. Identifiable risk factors include excessive hydration and use of NSAID. Impaired free water clearance during exercise potentiated by COX inhibition provides a pathophysiological explanation for these observations.

Sodium Status of Collapsed Marathon Runners

Context.—Recommendations for prevention and treatment of medical emergencies in participants in marathon races center on maintenance of adequate hydration status and administration of fluids. Recently, new recommendations for fluid replacement for marathon runners were promulgated by medical and athletic societies. These new guidelines encourage runners to drink ad libitum between 400 and 800 mL/h as opposed to the previous “as much as possible” advice.

Objective.—To assess the sodium and hydration (plasma osmolality) status of collapsed marathon runners after the promulgation of new hydration guidelines.

Design.—Plasma sodium and osmolality values of runners who presented to the medical tent at the finish line of the 2003 Boston Marathon were measured.

Results.—Using reference ranges derived from the general population, of 140 collapsed runners, 35 (25%) were hypernatremic (sodium, &gt;146 mEq/L) and 6 (12%) were hyperosmolar (osmolality, &gt;296 mOsm/kg H2O), whereas 9 (6%) were hyponatremic (sodium, &lt;135 mEq/L) and 8 (16%) were hypo-osmolar (osmolality, &lt;280 mOsm/kg H2O). Compared with a population of marathon runners who had experienced no medical difficulties, 9% of the runners were hypernatremic, 5% were hyponatremic, 8% were hypo-osmolar, and none were hyperosmolar.

Conclusions.—Our findings indicate a significant incidence of hypernatremia with hyperosmolality and hyponatremia with hypo-osmolality among collapsed runners despite the new fluid intake recommendations, suggesting that either further educational measures are required or that the new guidelines are not entirely adequate to prevent abnormalities in fluid balance. Furthermore, the immediate medical management of hypernatremia and hyponatremia is different. Administration of fluids to severely hyponatremic patients may result in fatal cerebral edema. Our findings caution against institution of treatment until laboratory tests determine the patient's sodium status.

Recommendations for treatment of hyponatraemia at endurance events

This review focuses on possible pathophysiology of exercise-associated hyponatraemia and its implication on evaluation and treatment of collapsed athletes during endurance events. Rehydration guidelines and field care have traditionally been based on the belief that endurance events create a state of significant fluid deficit in athletes, which must be corrected by liberal hydration. Beliefs in the necessity of liberal hydration may have contributed to cases of hyponatraemia. Assumptions that fluid loss accounts for the entire weight loss during exercise and that fluid ingestion is the only source of water gain during exercise may lead to an overestimation of the degree of volume depletion and the amount of fluid needed for replacement. Increasing evidence suggests that hyponatraemic athletes are fluid overloaded; ingestion of large amount of hypotonic fluid in combination with inappropriate or inadequate physiological responses leads to excessive retention of free fluid. Risk factors include hot weather, female sex, slower finishing time, and possibly the use of nonsteroidal anti-inflammatory medications. Symptoms of hyponatraemia can be subtle and can mimic those of other exercise-related illnesses, thereby complicating its diagnosis and leading to possible inappropriate treatment. Most athletes who collapse at the finish line experience exercise-associated collapse, a benign and transient form of postural hypotension that can be treated simply by continued ambulation after finishing or elevation of legs while in a supine position for those who cannot walk. Care providers should consider the use of intravenous hydration with normal saline carefully since it is not needed by most collapsed athletes and may worsen the condition of patients with unsuspected hyponatraemia. Historic information and clinical signs of volume depletion should be elicited prior to its use. Most hyponatraemic athletes will recover uneventfully with careful observation while awaiting spontaneous diuresis. Use of hypertonic saline should be reserved for patients with severe symptoms. Moderate consumption of carbohydrate-electrolyte solution during exercise may allow the maintenance of adequate hydration and the prevention of hyponatraemia.

Sports and performing arts medicine. 3. Lower-limb injuries in endurance sports

This self-directed learning module highlights new advances in this topic area. It is part of the study guide on sports medicine and performing arts in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. This article uses case vignettes as a vehicle to elaborate on (1) ankle pain in a runner, (2) heel pain in an adolescent, (3) anterior knee pain in a runner, (4) lateral knee pain in a cyclist, (5) shin splints in a runner, (6) buttock pain in a hiker, and (7) collapse of a marathoner from hyponatremia.

OVERALL ARTICLE OBJECTIVE

To summarize lower-limb injuries commonly seen in endurance sports.