Sports medicine/case report
Unique Obstacle Race Injuries at an Extreme Sports Event: A Case Series

https://doi.org/10.1016/j.annemergmed.2013.10.008Get rights and content

Obstacle course endurance events are becoming more common. Appropriate preparedness for the volume and unique types of injury patterns, as well as the effect on public health these events may cause, has yet to be reported in emergency literature. We describe 5 patients who presented with diverse injuries to illustrate the variety of injuries sustained in this competitive event. In particular, 4 of the patients had a history of contact with electrical discharge, an obstacle distinctive to the Tough Mudder experience.

Introduction

The Tough Mudder is a 10- to 12-mile course in a class of endurance obstacle courses known as MOB (mud, obstacles, beer) runs.1 Since its inception by an entrepreneur and the first event in 2010, it has expanded from 3 to 35 locations and has had 700,000 participants worldwide.2 Unlike competitive timed races focused on individual performance, an obstacle course may be more likely to challenge stamina and build camaraderie through the teamwork required to successfully proceed through the obstacles and complete the course. There are 20 to 25 obstacles that participants may jog between in the course; the sequence and exact selection are kept secret until the event day. A list of possible obstacles and recommended training3 are listed in Table 1. Popular obstacles include “electroshock therapy” (Figure), in which participants must run through mud and water while dodging electrical wires delivering “10,000 volts of electric shock,” and “walk the plank,” “a 15+ foot high jump into freezing water,”3 the obstacle cited in the media recently after the accidental death of a participant in West Virginia.4

The 2-day event took place the weekend of June 1, 2013, during which a single Pennsylvania hospital had 38 emergency department (ED) visits. This series received expedited approval by our hospital's institutional review board. We describe 5 patients who presented with diverse injuries; 4 were associated with electrical obstacles, a unique risk to this type of endurance event.

An 18-year-old man with a negative past medical history arrived by emergency medical services (EMS) for chest discomfort. He self-reported that it began immediately after he received 13 electrical shocks during the last obstacle in a Tough Mudder race. On protocol, EMS gave him aspirin (324 mg) and nitroglycerin. The patient was a nonsmoker, and family history was negative for heart disease. His vital signs were blood pressure 138/88 mm Hg, pulse rate 89 beats/min, respiratory rate 19 breaths/min, temperature 99.4°F (37.4°C), and oxygen saturation 100%. The CBC count and chemistry panel results were unremarkable, and the creatine phosphokinase level was 1,099 u/L (normal 30 to 170 u/L). The first troponin I level was 0.47 ng/mL (normal <0.04 ng/mL), his second had increased to 5.17 ng/mL, and the third was 23.62 ng/mL. ECG showed normal sinus rhythm with rightward axis and ST elevation related to early repolarization. The patient was admitted to the hospital.

Cardiology was consulted and noted on their examination that the patient had multiple burn marks consistent with electrical injury on his upper back and posterior right arm. A 2-dimensional echocardiogram showed normal structure and function. Cardiac magnetic resonance imaging (MRI) showed mild left-sided atrial enlargement and inferior and lateral akinesis with subendocardial late gadolinium enhancement, suggesting infarction or possibly an atypical presentation of myocarditis.

His troponin level trended downward and he was discharged on day 2. His final diagnosis was myocarditis caused by electrical shock.

A 28-year-old man arrived by EMS for severe headache and altered mental status. He sustained multiple electrical shocks to the head while running through the water in an obstacle and experienced syncope and altered mental status thereafter. He was not submerged or underwater. He had a past medical history of hypertension (while being treated with lisinopril). His vital signs were blood pressure 180/110 mm Hg, pulse rate 88 beats/min, respiratory rate 16 breaths/min, temperature 98.0°F (37.2°C), and oxygen saturation 99%. On examination, he was slow to respond but awake and oriented to person, place, and time. His speech was normal and he had no gross cranial nerve deficit or facial weakness. He had no abnormal cerebellar findings; no abnormal finger-to-nose test; no weaknesses, motor, or sensory deficits; and no pronator drift. His rhythm strip was normal sinus rhythm, but his ECG had diffuse ST elevation (early repolarization versus pericarditis) and an abnormality in V1, suggesting right ventricular conduction delay. His telemetry monitoring throughout his stay showed no arrhythmia. His CBC count showed a hemoglobin level of 11.6 g/dL (normal 13.5 to 18.0 g/dL) and WBC count of 16.9 thou/mm3 (normal 4.5 to 11 thou/mm3). His chemistry panel result was normal except for a sodium level of 127 mEq/L (normal 135 to 146 mEq/L) and potassium level of 3.1 mEq/L (normal 3.5 to 5.2 mEq/L). Creatine phosphokinase was initially 1,841 u/L and trended downward to 1,625 u/L and finally 1,333 u/L. Serial troponin levels were less than 0.04 ng/mL. Urine specific gravity was less than 1.005 and was not tested for myoglobin. Blood urea nitrogen was 13 mg/dL (normal 10 to 26 mg/dL), and his creatinine level was 0.75 mg/dL (normal 0.7 to 1.5 mg/dL). The patient was admitted to the hospital.

An echocardiogram showed normal cardiac structure. Computed tomography (CT) of his brain showed no evidence of acute intracranial hemorrhage, mass lesion, or acute major arterial territory infarct. No definitive cause for his change of mental status was elicited, and the patient was discharged on day 2, having normal neurologic examination results and diagnoses of accelerated hypertension, electrolyte imbalance, and possible pericarditis from electrical current injury.

A 31-year-old man with a negative past medical history arrived by EMS for right-sided weakness and altered mental status. At the scene, he was witnessed to have had possible seizure activity, details unknown. He had completed 20 of 22 obstacles when he developed sudden onset of speech difficulty, confusion, and inability to move his entire right side. EMS administered oxygen and started 2 peripheral intravenous lines. Glucose level was normal. He never smoked and exercised regularly (ran 2 to 3 miles/day), and his family history was negative for heart disease or stroke. Initial vitals signs were blood pressure 178/111 mm Hg, pulse rate 98 beats/min, respiratory rate 18 breaths/min, temperature (checked twice) 98.5°F (36.9°C) rectally/99.3°F (37.4°C) tympanic, and oxygen saturation 93%. His initial NIH Stroke Scale result was 9, with significant right-sided weakness of his hand, leg, and foot. CBC count showed abnormality of the WBC (21.3 thou/mm3; normal 4.5 to 11.0 thou/mm3), with a differential of 90 neutrophils, 41 lymphocytes, and 6 monocytes. Pertinent chemistry results were CPK 200 U/L (normal 30 to 170 U/L), troponin 0.08 ng/mL, magnesium 2.1 mg/dL (normal 1.8 to 2.4 mg/dL), and lactate 3.1 mmol/L (normal 0.5 to 2.1 mmol/L). An ECG result was normal. The patient's head CT scan showed small cortical sulci, which in this clinical setting raised the question of diffuse brain swelling, and also showed a subtle ill-defined hypodensity in the peripheral left frontal lobe.

The patient was admitted to the ICU, with a working diagnosis of Todd's paralysis. Subsequent MRI was significant for a moderate-sized left-sided middle cerebral artery stroke and a small-sized left-sided posterior cerebral artery stroke. CT angiogram result was negative for any significant dissections or stenosis or aneurysms, but was significant for a major branch occlusion. The patient began receiving full-dose aspirin.

A 2-dimesional echocardiogram result was essentially normal except for trace mitral regurgitation. His electroencephalogram result was normal. The patient was discharged on day 4 to a rehabilitation center, with a final diagnosis of left middle cerebral artery cerebral vascular accident, dehydration, and cardiac demand ischemia. At 6 weeks postinjury, he still had residual right lower extremity deficit.

A 41-year-old man arrived by EMS, complaining of facial and head injury after syncope. On the last course obstacle, he was struck by 2 electric cords in the head. The jolt caused him to lose consciousness and land face first in a hard mound of dirt. His past medical history was positive for hypertension and reflux (while being treated with Losartan potassium and Esomeprazole magnesium). Initial vital signs were blood pressure 140/90 mm Hg, pulse rate 98 beats/min, respiratory rate 20 breaths/min, and temperature 99.9°F (37.7°C). His examination showed full-thickness skin loss to the forehead and a glabella wound and spontaneous hemostasis of epistaxis. His neurologic examination revealed normal speech and no motor or sensory deficit, and he was alert and oriented to person, place, and time. His urine showed normal specific gravity with small ketones. CBC count, chemistry panel, and urinalysis were performed, with abnormalities of his WBC count (15.2 thou/mm3: 82 neutrophils, 9 lymphocytes, and 9 monocytes), creatine phosphokinase at 717 u/L, and troponin at 0.1 ng/mL. His ECG was normal sinus rhythm, with nonspecific ST abnormalities. His CT results of the head and facial bones were negative. Plastic surgery was consulted for evaluation of his extensive forehead wound. The consulting surgeon applied antibiotic dressing to the forehead wound and advised follow-up to assess healing by secondary intention in the office within a week. The glabella wound was repaired by the emergency physician at the surgeon's request. Having decisionmaking capacity, he was subsequently discharged from the ED against medical advice, with diagnoses of syncope, closed head injury, electrical injury from direct contact with source, lacerations to the face, and hypertension.

A 25-year-old woman arrived by EMS. At the last obstacle, just before the finish line, she was shocked on the right side of the chest. She felt light headed and near-syncopal, and she was handed a beer to drink. According to EMS personnel, during transport the patient stated that she was anxious, felt as if her heart were racing and she might pass out, and was incontinent of urine in the ambulance. Out-of-hospital vital signs were not reported to be abnormal, nor was ectopy reported on her out-of-hospital rhythm strip during her symptoms. Her last menstrual period was more than 2 weeks before the examination.

Initial vitals signs were blood pressure 136/72 mm Hg, pulse rate 85 beats/min, respiratory rate 20 breaths/min, temperature 99.1°F (37.3°C), and pulse oximetry 100%. She appeared anxious and restless, but otherwise her examination was unremarkable. Her ECG result was normal. Pertinent laboratory study results were creatine phosphokinase 10,152 U/L, large microscopic blood in the urine, which had a specific gravity of less than 1.005 (normal 1.003 to 1.030), WBC count of 14.5 thou/mm3 (83 neutrophils, 11 lymphocytes, and 6 monocytes), blood urea nitrogen 18 mg/dL (normal 10 to 26 mg/dL), creatinine 0.86 mg/dL (normal 0.7 to 1.5 mg/dL), aspartate aminotransferase 175 U/L, and alanine aminotransferase 52 U/L (normal 7 to 40 U/L).

The patient was admitted for dehydration and rhabdomyolysis. She was discharged the next day without sequelae.

Section snippets

Discussion

The burden on EMS during this event was unanticipated. Reportedly, more than 100 advanced life support responses were activated, with many patients receiving initial treatment and then refusing transport. As observed by the diversity and severity of the illness reported, it stands to reason that events such as the Tough Mudder and endurance races like it (eg, Warrior Dash, Spartan Race) may carry higher inherent risk factors for injury. This may be related to the preparatory ability for the

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