It is not uncommon to feel lightheaded right after exercising. But if you feel lightheaded hours after a workout or this problem continues or develops a day after a workout involving your legs, do not ignore it. It may not be related to your exercise.
The possible causes vary, but dizziness is a symptom that requires an investigation. It's smart to consult your doctor if you feel lightheaded often to rule out a medical problem. The dizziness may happen in correlation with your leg workouts, but it's unlikely that your exercise routine causes it.
Leg workouts specifically are probably not causing your lightheadedness, but exercise in general. You should see your doctor if this lightheaded feeling continues as it may be an indicator of a medical problem.
Dizziness After Exercise
Exercising affects your body in a number of ways. A leg workout requires an increase in oxygen to the active muscles. To accommodate this need, your heart may beat faster and your blood pressure goes up. When you complete your exercise, the blood pressure should return to normal.
This may cause some dizziness immediately after your routine, but it should not continue for a day. The Cleveland Clinic says you may be suffering from postural orthostatic tachycardia syndrome, or POTS. They suggest performing leg workouts sitting down with a machine such as the leg press.
Read more: What Is Normal for Blood Pressure?
Low Blood Pressure or Hypotension
Hypotension — the medical term for low blood pressure — may result in dizziness, according to Mayo Clinic. Low blood pressure can occur for many reasons. Standing up suddenly can cause a drop in blood pressure. You may also develop low blood pressure if you take certain medications such as diuretics.
Other symptoms of hypotension include fatigue, weakness, blurry vision and mental confusion. Avoiding alcohol and increasing the amount of water you drink each day may help. Hypotension is not related to a leg workout.
Irregular Heart Beat
Feeling lightheaded and faint, or presyncope, can indicate an issue with your heart health. When the heart isn't pumping blood adequately, you may feel lightheaded. Cardiovascular insufficiency can be due to an irregular heart beat or be a symptom of damage to the cardiac muscle.
When your brain does not receive enough blood, you feel dizzy. A heart condition may cause you to be lightheaded while you exercise, says the American Heart Association, but you probably feel it other times, too. If you have a history of heart conditions in your family, see a doctor to rule out an underlying cardiac condition.
Other Possible Explanations
Other medical conditions also cause you to feel lightheaded and it's unlikely they're caused by your leg workout. It may represent an inner ear infection, which is affecting your balance. Feeling faint may point to poor diet or the onset of diabetes. The fact that you exercised is secondary to the problem.
If the dizziness is severe or persists, avoid working out again until you see a doctor. Exercise could exacerbate a serious underlying health condition.