Hypothermia - What Every Open Water Swimmer Should Know
How to spot the ‘umbles’ and protocols for re-warming after a cold water swim.
Whether you’ve been swimming all summer, just getting into the Bay or considering swimming through the winter, hypothermia is always a risk that every open water swimmer and triathlete should be aware of.
Cold Water Shock v. Hypothermia
That gasp when you first enter the water, sometimes followed by uncontrollable breathing, a rapid heartbeat, and a quick-cooling of the skin, is a cold water shock response. Entering the water slowly can help alleviate much of this. Focus on your exhale and get your face wet to help ease yourself into the water.
What is Hypothermia?
Hypothermia occurs when your body loses heat faster than it can produce it, causing your core temperature to drop. As your skin cools and your body continues to lose heat, blood is shunted to the core to protect vital organs. The reduced blood flow to the muscles in your arms and legs means reduced power and energy. Unacclimated, prolonged time in cold water can lead to severe hypothermia and even death.
Symptoms of Hypothermia - the ‘umbles
There are both behavioral and physical symptoms that can be observed when someone is approaching mild hypothermia. From confusion, decreased coordination, aggression, poor judgment, to shivering and slurred speech, being aware of yourself and others in your group is key.
Mumbles - Slurred speech, confusion, delay in answering simple questions.
Grumbles - A swimmer who is argumentative, cranky, belligerent or out of character.
Fumbles - Decreased coordination, change in stroke rate, slower pace, sinking hips and legs, feeling of heaviness or drowsiness.
Stumbles - Difficulty standing, walking, or managing overall balance.
IF YOU THINK YOU’RE GETTING COLD - GET OUT!
Better to get out too early than too late
How to Minimize the Risk of Hypothermia
While you can’t completely eliminate the risk of hypothermia in open water swimming, you can follow some tips to delay its onset. See our Best Practices for Open Water Swimming in Winter, including gear and acclimation.
Keep these cold water essentials in mind:
Fuel is Heat: Eat a snack before you swim. Your body needs calories to generate energy to keep your core warm.
Avoid Alcohol: If you enjoyed alcohol the night before, it can actually cause your body to lose heat faster.
Keep Moving: Stopping or going vertical, and waiting for your fellow swimmers, shunts the cooler blood from your extremities back to the core. Circle around to keep moving and staying horizontal.
Watch the Clock: Always wear a watch with a timer to track and know how long you’ve been in the water.
If a Swimmer is Cold: Recovery Protocol
If you or a fellow swimmer start showing signs of the ‘umbles,’ it is time to act. Do not send a cold swimmer back to shore alone.
1. The Immediate Exit
Exit Together: Never let a cold swimmer walk back to re-warm alone.
Sit Down: Once everyone is back to the changing area, sit down to avoid stumbling or falling.
Remove Wet Gear: Cold, wet layers continue to pull heat from the body.
2. Re-Warming (The Do’s & Don’ts)
✅ DO Dry off and Layer Up: Put on dry, warm layers of clothing, including a hat.
✅ DO Apply Gentle Heat: Place heat packs (like HotSnapZ) or warm water bottles on the stomach, armpits, and groin area. A sauna isn’t always available, but a car with the heat blasting can work well!
✅ DO Allow Shivering: This is your body’s natural heater working. It’s a good sign.
✅ DO Sip Warm Liquids: Warm water, hot chocolate, and tea are lovely.
❌ DON’T Take a Hot Shower: The warm water forces the cooler blood to your core faster, and “Afterdrop” may intensify, causing lightheadedness, dizziness, or even fainting.
❌ DON’T Drive: Do not drive until you are completely warm and your coordination is 100%.
Severe Hypothermia Warning
If a swimmer is unconscious, unresponsive, has stopped shivering, or shows blue/gray skin coloration, get them out of the water, out of the elements, and call 911 immediately. Do not attempt rewarming without professional guidance.
A word about Afterdrop…
Your body continues to cool even after you exit the water. Afterdrop occurs as blood circulates from cooler extremities back through the core, often causing intense shivering. In a typical recovery, shivering subsides as your body rewarms. However, if symptoms worsen, shivering stops, or you feel increasingly disoriented, seek medical attention.
Disclaimer: This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Open water swimming involves inherent risks, including cold exposure, hypothermia, disorientation, injury, and death. Conditions vary by location, weather, and individual health.
Further educate yourself about hypothermia, its symptoms, and how to respond before participating in cold water swimming. Consult a physician regarding cold water exposure and your personal health. Never disregard professional medical advice or delay seeking it because of information in this article.
Never swim alone. Be aware of how you’re feeling and how others are behaving. Watch for signs of distress, hypothermia, or anything that seems off. Cold water conditions can become hazardous quickly if you’re uninformed, unaware, unprepared, or unhealthy.
If something doesn’t feel right, stop swimming and exit the water immediately. Assess your condition. If symptoms persist or you believe your health is at risk, seek medical attention or call 911.
You are responsible for your own decisions and should assess conditions, your experience, and your physical state before entering the water. Thanks for reading!
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