Why Do I Get Lightheaded After Workouts?

  • 1st Revision: Bea Brownlee


Exercise in whatever form is an important part of your weekly routine. It is associated with many health benefits. However, it can become unenjoyable and daunting if you experience negative symptoms such as lightheadedness afterwards.

If you feel lightheaded after exercising, the good news is that this article may have the answers as to why. On top of that, there is also guidance on what to do when you do encounter lightheadedness after exercising and how to avoid this sensation in the future. 

Possible causes of being lightheaded after workouts


Dehydration is known to decrease blood volume and can make you feel lightheaded. Dehydration may be caused or influenced by several factors, which include vomiting, taking medication that causes you to lose a lot of water (e.g. diuretics) or simply not drinking enough water throughout the day.

Our bodies are thought to be at least 55% water.1 If you are dehydrated, your blood pressure usually decreases, which may cause the lightheadedness that you are experiencing.2 Harvard Medical School suggests drinking 4-6 cups of water daily, or more depending on your physical activity level that day. 

Low blood sugar

The food you eat is broken down into glucose (blood sugar) by your body. Glucose is your body’s main source of energy. Excess glucose is stored in your liver in the form of glycogen.2 

During exercise, your muscles take up and utilise glucose at a significantly higher rate than when you are at rest.3 The muscles start off by using the glucose in your bloodstream before using glycogen. More intense workouts require more energy, so more glycogen is broken down into glucose to provide you with sufficient energy.4 Sprinting, for example, will use up glycogen at a high rate because of the intensity of the activity. 

If you have not eaten enough, you may not have glucose in your bloodstream, and you can see how that would be a problem. This essentially means that you do not have enough glucose available to generate energy, so your body starts looking for alternate sources of fuel for your workout. You may end up feeling lightheaded and dizzy if you do not have enough reserve fuels (e.g. glycogen and fats) that your body can convert to energy. 

Other symptoms of low blood sugar include:

  • Shaking
  • Hunger or nausea
  • Headaches
  • Sweating
  • Irregular or fast heartbeat
  • Tingling or numbness of the lips, tongue or cheeks  

Signs and symptoms of worsening hypoglycemia (low blood sugar) include: 

  • Confusion 
  • Loss of coordination 
  • Slurred speech 
  • Blurry vision

Not eating enough also leads to having inadequate calories (another form of energy), which can cause demanding activities like weight-lifting or cardio to make you feel lightheaded.  


A quick change in position, particularly moving from lying or sitting to standing, can cause a feeling of lightheadedness to pop up. This rapid posture change results in orthostatic hypotension or postural hypotension, which means a drop in blood pressure. This feeling of lightheadedness comes on quickly (within 3 minutes) and is usually short-lived.5


Although you may love a good workout that challenges you, pushing too hard can lead to lightheadedness and/or dizziness by causing a blood pressure drop or dehydration. 

If you are trying out a new type of exercise, it may be best to pace yourself and start off slowly, then gradually increase the intensity. Doing this could help you avoid that lightheaded feeling. 

Doing high-intensity workouts while poorly hydrated may be the cause of your lightheadedness. As discussed earlier in this article, dehydration does not mix well with intense exercise, or any level of exercise for that matter. 


During exercise, especially high-effort ones like lifting heavy weights, it is important to keep breathing properly. Sometimes, our reflex action (automatic response) when the difficulty level of an exercise increases or when doing core exercises is to hold our breath. This is harmful because when exercising, your body requires a lot more oxygen to make sure that muscles can work properly without getting tired quickly. This is why your heart rate and breathing rate increase during exercise, to meet that increased demand for oxygen. 

Holding your breath or not breathing enough means that your muscles and brain can’t receive as much oxygen as they need. This is how you end up feeling lightheaded after exercising.6 

Management and treatment for being lightheaded after workouts

If you find yourself feeling lightheaded after exercise, here are a few things you can do to help that feeling subside:

  • Take a break, and take a few deep breaths
  • Drink a few sips of water to replace some of the water lost during your workout
  • Have a snack to increase your blood sugar levels

How can I prevent being lightheaded after workouts?

  • Make sure that you are adequately hydrated (4-6 cups a day). Bring a water bottle to the gym and make sure you take sips from it often (e.g. after every exercise set)
  • Make sure to warm up beforehand and increase the intensity of your workout gradually. Push yourself but don’t overdo it. Listen to your body and take breaks when necessary 
  • Don’t hold your breath - make sure you are breathing properly throughout your workout, and pay extra attention to your breathing when you increase the difficulty
  • Make sure you are eating a minimum of 3 substantial meals a day, as well as some healthy snacks when necessary. On days where you’re doing higher-intensity exercise, consider eating more. Avoid sugary foods, as these cause your blood sugar levels to spike and then crash back down to low levels

When should I call a doctor?

In some cases, your lightheadedness may signal an underlying health concern. If you see no improvement after following the management and treatment advice as well as preventative measures, then seek medical attention. 


Lightheadedness after exercise can be caused by a variety of factors, including dehydration, low blood sugar, changing position and pushing too hard. When you experience lightheadedness, take a few deep breaths and drink some water. Ensure you are adequately hydrated and eating well before exercising. It is okay to push yourself during workouts, but make sure you aren’t doing more than your body can manage. 


  1. Popkin BM, D’Anci KE, Rosenberg IH. Water, Hydration, and Health. Nutrition Reviews [Internet]. 2010 Jul 20;68(8):439–58. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2908954/
  2. Hargreaves M, Spriet LL. Skeletal muscle energy metabolism during exercise. Nature Metabolism [Internet]. 2020 Aug 3;2:817–28. Available from: https://www.nature.com/articles/s42255-020-0251-4.epdf?sharing_token=fj5I_4RE8DYyTDKPyiO8DdRgN0jAjWel9jnR3ZoTv0O-dVouN28agZwuuaYjsHydJiEorgb2zDV3lleuMQ5An4_sPT40VCDYQ2xAX8_8_Vhsq8rV0Erm9mn_KPcLu7a1QeddlHHMNAdFYHJuzclsq1aaLMss0U_HajjHkB2MznY%3D
  3. Richter EA, Derave W, Wojtaszewski JFP. Glucose, Exercise and insulin: Emerging Concepts. The Journal of Physiology [Internet]. 2001 Sep;535(2):313–22. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2278791/
  4. Murray B, Rosenbloom C. Fundamentals of glycogen metabolism for coaches and athletes. Nutrition Reviews. 2018 Feb 10;76(4):243–59.
  5. Ringer M, Lappin SL. Orthostatic Hypotension [Internet]. PubMed. Treasure Island (FL): StatPearls Publishing; 2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448192/
  6. Dujic Z, Breskovic T. Impact of Breath Holding on Cardiovascular Respiratory and Cerebrovascular Health. Sports Medicine. 2012 Jun;42(6):459–72.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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