Many things can cause lightheadedness and weakness during workouts, some of which are more serious than others. The Mayo Clinic describes lightheadedness as feeling dizzy or like you might faint, while Medline Plus describes weakness as a lack of strength. Feeling lightheaded and weak while working out is not normal; it indicates a problem that needs to be diagnosed and corrected.
Dehydration
According to the Mayo Clinic, one of the most common causes of dehydration is not drinking enough fluids while exercising, especially during hot weather. Symptoms of dehydration include dry mouth, thirst, and headache, as well as lightheadedness and weakness. To prevent dehydration while exercising, drink before, during, and after workouts. Don’t wait until you feel thirsty to drink.
Hypotension (Low Blood Pressure)
Many things can cause hypotension during workouts, including dehydration. Symptoms of hypotension while exercising may include blurred vision and nausea, as well as weakness and lightheadedness. You can buy a home blood pressure monitor at any drugstore to test your blood pressure. According to Medical News Today, a reading of 90/60 mmHg or lower indicates hypotension.
Hypoglycemia (Low Blood Sugar)
According to the National Diabetes Information Clearinghouse, a blood glucose level below 70 mg/dL indicates hypoglycemia. Increased physical activity can lead to hypoglycemia, especially if you have diabetes or if you haven’t eaten recently. Symptoms of hypoglycemia include hunger, shakiness, anxiety, and profuse sweating, along with lightheadedness and weakness. Eating something that contains sugar, like hard candy or fruit juice, usually resolves the problem quickly. To prevent hypoglycemia when exercising, eat a healthful snack an hour or so before beginning your workout.
If you exercise outdoors during hot weather, you need to watch out for heat exhaustion. Symptoms of heat exhaustion include nausea, confusion, and muscle cramps, as well as lightheadedness and weakness. If you begin to experience symptoms of heat exhaustion, you need to cool down immediately in order to prevent heat stroke, which can be deadly. To reduce your risk of heat exhaustion, the Mayo Clinic recommends you avoid exercising outdoors during extremely hot weather, drink plenty of water, and wear loose-fitting, light-colored clothing.
Illness
A common cold, flu, or other infection can cause feelings of weakness and lightheadedness, which can increase during exercise sessions. It’s probably best not to exercise when you’re ill. If you’re concerned about missing a workout, check with your doctor to make sure it’s safe for you to exercise before you’ve fully recovered.
Heart Problems
According to “The New York Times,” though less common than other causes of weakness and dizziness while exercising, heart problems can cause lightheadedness. Exercise, especially vigorous exercise, may exacerbate symptoms. If you have a known heart condition, talk to your doctor before beginning an exercise program. If you experience lightheadedness or weakness while exercising and don’t know why, see your doctor to make sure it’s nothing serious, like a heart condition.
Sources:
Mayo Clinic. http://www.mayoclinic.com/health/dizziness/DS00435 Dizziness.
Medline Plus. http://www.nlm.nih.gov/medlineplus/ency/article/003174.htm Weakness.
Mayo Clinic. http://www.mayoclinic.com/health/dehydration/DS00561 Dehydration.
Medical News Today. http://www.medicalnewstoday.com/articles/241527.php What Is Normal Blood Pressure?
National Diabetes Information Clearinghouse. http://diabetes.niddk.nih.gov/dm/pubs/hypoglycemia/ Hypoglycemia.
Mayo Clinic. http://www.mayoclinic.com/health/heat-exhaustion/DS01046 Heat Exhaustion.
The New York Times. http://health.nytimes.com/health/guides/symptoms/dizziness/overview.html Dizziness.
