When a Child Collapses During Exercise: Heart and Heat Warning Signs

A Secondary school student died in Singapore yesterday morning (1 August). He had collapsed after a 2.4 km run in school...

A teenager finishes a 2.4km run, walks a few steps, and drops. Stories like that surface every so often, and they leave parents of active, sporty children with a quiet fear: could this happen to mine, and would I recognise the warning signs in time? Collapse during exertion has a small number of causes, most of them detectable, and one of them is made worse by the weather outside your front door.

Collapse during exercise is rare, and the two main causes in young people are a hidden heart condition and heat injury. Chest pain, fainting or breathlessness during exertion should always be checked by a doctor before the child plays on.

Heat is the manageable risk in Singapore: hydration, acclimatisation and rest prevent most heat collapse.

Why young people collapse during exercise

It’s important to keep this in proportion: sudden collapse in a child or teen during sport is uncommon, and exercise is overwhelmingly good for them. When it does happen, the main causes are:

A hidden heart condition, such as an inherited heart muscle disorder or an electrical rhythm problem, which can cause sudden cardiac arrest. These are rare and often silent until stressed by hard exercise.
Heat injury, from exercising hard in heat and humidity, ranging from heat exhaustion to life-threatening heat stroke. This is the more common and more preventable cause in Singapore’s climate.
Less commonly, low blood sugar, severe asthma, dehydration, or a bad allergic reaction. If your child has a known trigger, brush up on the signs of food allergy and anaphylaxis in children and make sure the coach knows where the adrenaline pen is kept.

The warning signs of a heart problem

The signs that a young athlete needs checking before continuing sport are:

Fainting or near-fainting during or right after exercise. This is the most important warning sign and should never be dismissed as “just tired” or “didn’t eat enough”.
Chest pain or tightness on exertion
Unusual, excessive breathlessness out of proportion to the effort
Palpitations, a racing or irregular heartbeat
Dizziness during exercise

A family history matters too: a close relative with a sudden, unexplained death before middle age, or a known inherited heart condition, is a reason to tell your doctor. Any of these means a check with a doctor, who can refer to a cardiologist if needed. Routine heart scans for every child aren’t recommended, because they throw up false alarms, but a child with symptoms or a family history should be assessed.

Heat injury: the risk you can manage

Singapore is hot and humid year-round, and heat injury is the exertion risk most within a parent’s and coach’s control. It builds as the body overheats faster than it can cool. Watch for:

Heavy sweating, then, worryingly, sweating stopping
Headache, dizziness, nausea, cramps
Confusion, unusual behaviour, or stumbling
Very high body temperature and collapse, which is heat stroke and a medical emergency

Prevent it with the basics: drink water before, during and after activity; build up training gradually so the body acclimatises; take breaks in shade; avoid the hottest part of the day for hard exercise; and stop at the first signs. A child who has been unwell recently starts on the back foot, since fluid losses take time to replace, and the same rules apply as with stomach bugs and keeping a child hydrated: small, frequent drinks beat one big gulp at the end. A child showing confusion or who collapses in the heat needs cooling immediately (move to shade, remove excess clothing, cool with water) and an ambulance on 995.

If a child collapses

Call 995 and shout for help.
Check for breathing. If they’re not breathing normally, start CPR, and send someone for the nearest AED (automated external defibrillator), which is found in many public places and schools. Early CPR and an AED save lives in cardiac arrest.
If it’s heat, cool them fast while waiting for the ambulance.

Knowing where the AED is, and the basics of CPR, is worth it for any parent whose child plays sport. It sits alongside the other household safety habits that only matter once, like window and fall safety at home: dull to set up, decisive on the day.

Common questions

Why do young athletes sometimes collapse during exercise?

Rarely, and usually from a hidden heart condition causing sudden cardiac arrest, or from heat injury in a hot climate. Less commonly, low blood sugar, severe asthma or a bad allergic reaction.

What are the warning signs of a heart problem in a child?

Fainting during or after exercise is the key one, along with chest pain on exertion, excessive breathlessness, palpitations or dizziness. A family history of sudden unexplained death also warrants a check.

Should my child have a heart screening before sports?

Routine scans for every child aren’t recommended, as they cause false alarms. But a child with warning symptoms or a family history of heart problems or sudden death should be assessed by a doctor.

How do I prevent heat injury during sport in Singapore?

Hydrate before, during and after, build up training gradually to acclimatise, take shade breaks, avoid the hottest hours for hard exercise, and stop at the first signs of overheating.

What should I do if a child collapses during exercise?

Call 995, check breathing, and start CPR and use an AED if they aren’t breathing normally. If it’s heat, cool them quickly while waiting for the ambulance.

Before the next training session

Don’t let this put you off signing your child up for anything. Collapse during sport stays rare, and the children who move are better off for it. But if yours has ever fainted on the field, felt chest pain running, or gone breathless in a way that didn’t match the effort, that’s a doctor’s appointment, not a water break. Ask your parents whether anyone in the family died young and unexplained. Then do the unglamorous work: fill the water bottle, build training up slowly, find out where the AED at the sports hall is kept. Most parents never need any of it. The ones who do never regret knowing.