S5E4: Exercise Associated Collapse - Sports Medicine
Welcome back to Episode 4 of TCR and it is marathon season! Did you get your lottery ticket for the Dublin Marathon 2025 today?
Join us today for our first Sports Medicine Episode of season 5, where we’re bring our case to the streets of Dublin. Liam Loughrey and Carl Byrne join our very own Leah Flanagan who finds herself running a marathon (she doesn’t believe she could do one, but we believe in her here at TCR)! This month our adult in the room is Dr Stephen Gilmartin. He is an Emergency Medicine Consultant at Sligo University Hospital with a special interest in Sports & Exercise Medicine and minor injuries. With experience acting as the team doctor for professional rugby and inter-county GAA teams, who better to correct our homework?
Our case
It’s a surprisingly hot day for October in Dublin, which is probably not what all the runners were expecting! Leah notes a fellow runner taking 3 or 4 cups of water at each water station and remarks to herself that this feels like a lot of water to be taking in. She’s at 30 km when she notices the same guy is now swaying and beginning to lose his running form. By the 31km mark, he is now unable to walk, and collapses.
““Amateur marathon runner transforms into ED doctor””
Leah runs to his side and immediately notes that he appears confused and is drenched in sweat - profusely sweating in fact. Given she’s been running the race herself, Leah is unable to formally assess, but feels his radial pulse and notes that it’s fast and his respiratory rate is also. We’re out of the hospital here so number one Call for Help!
Our approach
Demonstrated in our infographic is a quick and concise approach to the collapsed patient. With limited equipment, it is super important to first call for help. Hot tips from our situation today are:
As the responder also is running the marathon, look to the exercise watch of the person to get the heart rate. It’s hard to differentiate your own pulse in that high-stress environment!
If there’s no medical aid nearby, call out to the supporters who will have their phones or check if the person has their phone to Call for help
Quick and brief airway assessment is helpful
Leah assesses his breathing to the best of her ability without equipment - she looks for tachypnoea which is present, cannot appreciate any wheeze from where she is and does not appreciate any abnormal breathing.
Cognition can be assessed with a GCS like in our scenario.
Check the racenumber for any conditions documented
Although we are limited, all of the above can really help for handover to medical staff and it’s a good use of the time spent waiting for assistance to arrive.
At the back of a race number, look for any conditions might be written on the back, and there may be a NOK number”
With our primary survey in our pocket, our AITR, Dr Gilmartin likes approaching these by asking the big three questions.
What’s the worst case scenario? (And why do I think it’s not?)
What’s it most likely to be?
What can I rule out fairly quickly?
For our middle aged, confused, hot and tachycardic man just after his long run on a hot day, let’s see what our questions yield:
What’s the worst case scenario?
(And why do I think it’s not?)
-
Description text goes hereFor this patient his pulse, blood pressure and ECG are looking ok. Although he’s tachycardic at 140, this isn’t overly concerning given he’s just after a big race on a hot day.
On the ECG we want to look carefully for any signs of a prolonged QTc, HOCM, clear heart block or any delta waves.
If the ECG is normal, this provides good reassurance that a cardiac cause is unlikely. -
Description text goes hereAn infection is unlikely given this patient was well enough to run the race to begin with. This patient had a GCS of 13/15. We cannot rule out a bleed although this is unlikely, but keep this in the back of your head as you work through the case, treat other causes and monitor the GCS at repeated intervals.
-
How are the vitals? He’s tachycardic but his blood pressure is ok and with a temperature of 38.2ºC this wouldn’t fit with a fulminant heat illness.
2. What’s it most likely to be?
-
Dehydration
Hear related illness
Exercise associated hyponatraemia
Hypoglycaemia
3. What can we check immediately and outrule?
-
Check glucose as part of our primary survey.
ABCDEFG - Don’t Ever Forget Glucose! -
Point of care sodium if available.
Exercise Associated Hyponatremia
-
Exercise associated hyponatraemia arises when people are taking on too much fluids. These patients aren’t drinking to thirst. They drink more than their kidneys can keep up with. We make urine at a rate of 1.5ml/kg/hr and for the average person this works out at roughly 100mls/hr. This is also compounded by certain medications. People may have taken NSAIDs for analgesia prior to the race putting added stress on our kidneys.
In some patients there may be an element of SIADH due to medications, heat and exercise, but the majority of patients with an exercise induced hyponatraemia is due to poor fluid management and overhydration.
-
Description text goes hereIt’s generally seen with endurance events lasting more than 2hrs and is less likely in team sport.
Slower paced athletes.
Less conditioned athletes; Training and conditioning the body for these endurance events is crucial. For example, more conditioned athletes have an increased ability to sweat and can cool themselves down faster than less conditioned athletes.
-
You may be lucky enough to have a point of care sodium checker or you may have to wait for the lab, but these patients need their sodium checked.
Interestingly, it is not the degree of hyponatraemia on the lab result that is important, but what matters is the patient’s symptoms. Symptoms can be classified into asymptomatic, mildly symptomatic and severely symptomatic.
-
For people with asymptomatic hyponatremia, you need to make sure that they’re urinating. This is a sign that their ADH has switched off. They need high salt content fluids and to watch out for further symptoms such as increased lethargy, confusion, nausea etc.
For symptomatic but not severe hyponatraemia; people with lethargy, malaise and nausea, it’s reasonable to monitor this cohort and give them some sodium containing oral solution in hospital. Make sure that they are passing urine first (making sure that their ADH is switched off) and once they have recovered symptomatically, it’s reasonable to send them home with some safety netting advice.
Severe These patients need urgent medical treatment. There is no target or limit by which to increase your sodium by. The aim is to treat the patient’s clinical signs and symptoms.
Give boluses of hypertonic saline. 1.5mls/kg of 3% NaCl. This is roughly 100ml bolus for the average person. If not available quickly, you can give 50mls of sodium bicarbonate 8.4% 50mls. This should be easier to find given it should be stored in the crash trolley!
Give a bolus every 10 mins until the symptoms improve. These patients need to come into the hospital. They need their inputs and outputs monitored closely and serial sodium levels checked.
-
It’s important to note that this is a case of very acute hyponatraemia occurring over 3-4hrs - unlike the indolent presentations we usually see coming into the emergency department. Central pontine myelinolysis only occurs 48hrs after sodium concentrations have changed. In exercise associated hyponatraemia, the sodium change happens much more acutely, hence the difference in treatment approach (no specific target and less risk with overcorrection).
As Carl notes, exercise induced hyponatremia is quite common in half and full marathons. 51% of runners are thought to get it at some point, but it’s often asymptomatic! Only 1% of runners will become symptomatic but they account for one third of the workload in the medical tents at the marathon events! It’s important to safetynet runners from the tent and educate on red flags of severe hyponatremia if they’re going home!
Management of hyponatremia differs in the ED. If it’s asymptomatic and an incidental finding; be sure to hold hypertonic fluids until they pass urine. Following this, we can start to build back in the sodium post voiding. Be sure to consult your local guidelines when operating within the ED, to get yourself out of a tricky situation -
Ideally load with electrolyte based fluids and snacks at the end of the race, careful not to overdo the water! Planning for the race is super important. You want to plan ahead and if you’re considering gels as an option for sodium (electrolyte or sugar based) intake during the race, it needs to be built into the training plan to get accustomed to them!
Exercise induced hyperthemia
This can be diagnosed when a core temp >40 is appreciated.
Note: the temperature is more accurate when taken rectally, peripheral changes in temperature can be inaccurate in this setting. Rectal probes are generally present at more official events!
Hot tips for EIH:
Take the temp rectally
More common in a hot country
Not impossible in colder countries, can still occur
If occurs on the side of the road
Take off excess clothing, put them in the shade, put cool fluids on them, call for help
Cautious about hypotonic saline
We don’t want to end up with simultaneous EAH
In the medical tent:
Pack them with ice (groin, axilla will be effective)
-
Syncope on exertion is concerning. Syncope after exertion is less concerning. Syncope after exertion occurs because of pooling of blood in lower legs leading to reduced preload and therefore reduced cardiac output, leading to presyncope leading to collapse.
Syncope on exertion may be due to an arrhythmia, valvular pathology or HOCM.
Screening
Screening is very controversial but various guidelines all agree that there is a lack of evidence in this area. At a minimum, screening should include a questionnaire, a physical exam and an ECG.
Questionnaires should look at personal medical histories, for example, Marfan’s syndrome and also family histories for cases of Brugada or sudden cardiac death.
Physical exams in particular should look for signs of Marfan’s syndrome or any murmurs.
ECG should look for Wolf Parkinson’s White, prolonged QT intervals and other arrhythmias and abnormalities.
-
There is no consensus across sports at present. The World Rugby Guidance advises biannual screening until age 20 years, The GAA enforces biannual screening and The FA includes an echocardiogram as part of their screening.
-
There are high false positive rates with screening programs which can have negative impacts as athletes are taken out of sport for a period of time until more definitive testing can be arranged. This may not be a big problem for professional athletes who have quick access to specialists but for amateur athletes this may not be the case. And who should follow up these tests? GPs? Team Doctors? The patient?
-
The Seattle criteria can help us interpret abnormal ECGs in athletes coming into the ED. It was created by Sports Cardiologist Dr Drezner, and it allows us to get a higher specificity without sacrificing sensitivity in identifying those patients who need to go on for further investigation and specialist input.
Rhabdomyolysis:
Rhabdomyolysis is the breakdown of muscle leading to a release of muscle breakdown products into the bloodstream. Myoglobin is one of these products, which causes damage to the kidney causing an acute kidney injury.
Diagnosis often relies on a CK level. Normal CK is <400U/L, but in true rhabdomyolysis the CK will be in the high thousands. It’s very unusual for someone to get fulminant rhabdomyolysis from regular exercise. It’s usually from people taking medications e.g. statins, recreational meds, or people involved in a crush injury. Most people usually have mild symptoms e.g. muscle aches.
-
If they have mild symptoms, normal vitals, normal renal function, they’re tolerating oral hydration and have a normal urine output, the patient can be discharged with safety netting and asked to remain vigilant looking at their urine colour.
-
This manifests as severe muscle aches, severe weakness, abnormal kidney function, abnormal electrolytes or CK levels in the high thousands.
These patients should be admitted.
Target IV fluids to the urine output - Give them substantial amounts to maintain 1-2mls/kg/hr - this helps excrete the myoglobin from the kidneys.
Monitor electrolytes and treat them as appropriate.
Consider giving sodium bicarbonate. Myoglobin decreases the pH of the urine. We want to help make the urine alkalotic to help excrete the myoglobin.
Heat related illness.
This is unusual when you live in Ireland but it may be seen. This presents similar to other exercise related illnesses, and usually the patient is having a normal response to exercise and may be deconditioned. They can be confused, tachycardic, pyrexic, and have an elevated CK level.
Patients will present mildly pyrexic, but a core temperature above 40ºC is rare.
-
High BMI
Longer runs
Hot conditions
Patients can be very unwell and can have fulminant organ failure.
-
Description text goes here
-
Ice bath immersion is the best cooling method. Least invasive and best. If you give fluids you run into trouble as they quickly warm up to body temperature, so you would need to give significant amounts. Risk of exercise related hyponatremia. Apply ice packs to the major arteries - groin and axillae.
More invasive measures - cold irrigation of the bladder and chest drains.
Take home messages
Exercise is great for us! People generally get more good out of it than bad. People feel great after it. If someone feels unwell after it, the good news is that they are probably fine, but always consider more serious pathologies.
Remember to always start your assessment with the primary survey and ask yourself Dr Gilmartin’s big three question:
What's the worst it can be?
What's most likely?
What can I outrule quickly?
