If you've ever finished a tough, sweaty workout only to feel chills a few minutes later, you're not alone. Cooling off after a workout is fairly normal, as your body's processes are attempting to maintain your core temperature.
As a warm-blooded mammal, your internal temperature remains relatively constant — at approximately 98.6 degrees. Moving that number up or down a whole degree requires specific circumstances, such as illness or extreme temperatures. However, wearing improper attire in cooler temps, dehydration and low blood sugar can cause you to feel post-workout chills.
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Still wondering, "Why do I get chills after exercise?"Ahead, learn more about the reasons why you might get chills after working out — plus how to prevent it from happening in the future.
1. You Skipped Your Cooldown
When you exercise, your body temperature increases. (Learn more about exercise's effects on body temperature.) Cooling down after a workout is beneficial because it gradually reduces your body temperature and regulates your blood flow back to where it was before your exercise session, according to the Mayo Clinic. Skipping a cooldown can cause a more drastic reduction in your body temp, which can lead to chills after running, biking, strength training and more.
To cool down properly, continue your workout but reduce your intensity and pace gradually for 5 to 10 minutes, according to the American Academy of Orthopaedic Surgeons. For instance, to cool down after a brisk walk, walk slowly for 5 to 10 minutes. If you were running, slow to a brisk walk for a cool down. After cycling, spin at higher revolutions per minute with low resistance. Also, stretch your muscles afterward to slow the blood flow through your body and reduce your injury risk.
2. You Didn't Dress Warm Enough
Wearing proper clothing can prevent chills during and after a workout. Layering your clothes, particularly if you're exercising outdoors in cold weather, is important in not only keeping chills at bay but hypothermia as well.
Layers trap warm air closest to your body, keeping you insulated. As you warm up you can strip off a layer to prevent excessive sweating, which can be dangerous in cold weather. That's because post-workout, your wet clothing will become cold, potentially dropping your body temperature too quickly.
Also note that cotton fibers tend to hold water, so choose fabric that dries quickly, like polyester, nylon and merino wool. Top your layers with a wind-resistant shell and a hat and gloves if the weather is cold.
3. You're Dehydrated
What you put in your body before your workout can play a role in how you feel post-exercise. Water is extremely important in regulating your body temperature, and a lack of it can lead to chills, according to the Cleveland Clinic.
How much you hydrate before, during and after a workout really depends on factors like your workout intensity and environment, per the University of Michigan. But general guidelines include:
- Drinking 17 to 20 ounces of water about 2 hours before a workout
- Drinking 7 to 20 ounces of water for every 10 to 20 minutes of exercise
- Drinking 16 to 24 ounces of water after exercising for each pound lost due to sweat
Other symptoms of dehydration include fatigue, headaches, muscle cramps, dry mouth, constipation, dark urine, swollen feet, loss of appetite, flushed skin and a high heart rate but low blood pressure, according to the Cleveland Clinic. Seek medical attention if you have any of these symptoms, as you may need hydration through an IV.
4. You Have Heatstroke
Taking your workout outdoors in higher temps can cause your body to overheat. If it's extremely hot and humid out, you may put yourself at risk for heatstroke.
Heat stroke occurs when your internal body temperature reaches over 103 degrees, according to Comanche County Memorial Hospital. Nausea and chills after exercise the heat are common symptoms of heatstroke, along with severe headache, confusion, racing heart rate, rapid breathing and vomiting.
If you or someone you know show signs of heatstroke, call 911 immediately, according to Comanche County Memorial Hospital. While waiting for help to arrive, try to find a shaded area, remove any excess clothing and wet your skin with cool water.
5. Your Blood Sugar Is Low
Low blood sugar, or hypoglycemia, after exercise can also lead to feeling chilled or experiencing cold hands and feet. Not eating enough during the day and then putting in an a long or intense workout leaves you at risk, per the Cleveland Clinic. (This is referred to as reactive hypoglycemia if you experience this and don't have diabetes.)
Post-exercise hypoglycemia is treatable and preventable, according to the Cleveland Clinic. If you experience low blood sugar after a workout, eating or drinking 15 grams of fast-acting carbs can help raise your blood sugar. To prevent it from happening in the first place, consuming eating carbohydrates low on the glycemic index — like fruits or whole grains — before your workout can keep your blood sugar stable.
Avoiding over-training can also prevent post-exercise hypoglycemia. Schedule rest days throughout the week and take breaks during a workout to give your body's fuel stores time to recover.
"Low blood sugar is common for people with type 1 diabetes and can occur in people with type 2 diabetes taking insulin or certain medications," per the American Diabetes Association (ADA).
If you have diabetes and have a hypoglycemic episode, consume 15 grams of carbs to raise your blood sugar and check it after 15 minutes. If it’s below 70 mg/dL after doing so, have another 15 grams. Continue doing this until your blood sugar is at least 70 mg/dL. Let your doctor know this happened so they can help you avoid it in the future.
If your blood sugar drops extremely low, seizures or unconsciousness can occur. If this happens to someone you know, call 911 immediately.
- American Academy of Orthopaedic Surgeons: "Warm Up, Cool Down and Be Flexible"
- Mayo Clinic: "Aerobic exercise: How to warm up and cool down"
- Cleveland Clinic: "Dehydration"
- Cleveland Clinic: "Hypoglycemia (Low Blood Sugar)"
- ADA: "Hypoglycemia (Low Blood Glucose)"
- University of Michigan: "The Importance of Water While Exercising"
- Comanche County Memorial Hospital: "The Difference Between Heat Exhaustion and Heat Stroke: When to Sweat It and Seek Care"