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Writer's pictureTara Pickham

Why do I get dizzy when I exercise?

Updated: Apr 30, 2023

It’s not totally unusual to feel lightheaded or dizzy while exerting yourself at the gym or even after you’ve finished your workout. Oftentimes this is no need for major concern but understanding why this is happening and how to stop it can help to reduce both the severity and frequency of these types of episodes. Let’s look at the reasons why this may occur and discuss what can be done to manage the symptoms.


Low Blood Sugar

Both our muscles and our brain need glucose (which we get from consuming carbohydrates) in order to function. When we exercise our muscles demand for glucose increases so that they have the energy required to perform each task. This can leave glucose stores depleted meaning our brain no longer has a sufficient supply of glucose and as a result we can become dizzy or lightheaded. This is referred to as low blood sugar or Hypoglycaemia. If you’re suffering from low blood sugar, consuming a light snack such as a piece of fruit can offer relief. If more immediate relief is required a simpler form of carbohydrates may be required and therefore a glass of juice would be a better option. When it comes to low blood sugar prevention is best. Plan your meals ahead so that your brain and muscles have the necessary glucose supplies. Consuming a meal of carbohydrates and a small portion of protein about 30-90min prior to training is recommended.


Dehydration

When we exercise our body temperature rises and our body sweats to cool it down. Dehydration occurs when we lose more fluid then we take in and this can cause dizziness and fatigue. Even mild levels of dehydration (a loss of 1-2% body weight) can lead to symptoms so it is important to be proactive with your hydration. Ensuring you always have access to water both during your workout and throughout the day as well as making sure you hydrate frequently can help you avoid dehydration and dizziness. Make sure to consider what type of conditions you live, work and train in as well as the intensity of your sessions when deciding on what is adequate hydration for yourself.


Low Blood Pressure

Blood pressure is the pressure of circulating blood on the walls of our blood vessels. Typically speaking our blood pressure is at its lowest 30-60min post exercise however for some people this decline in blood pressure happens at far more rapid rate. When we exercise our muscles require more oxygen which means our heart must pump faster to supply this extra oxygen. When we stop exercising, the oxygen needs of our muscles quickly declines and returns to normal just as our heart rate does. Our blood vessels however can take longer to adapt to this change which means the flow of oxygenated blood to the brain is slowed and this is when dizziness can occur. A healthy blood pressure is around 120/80 but people who have hypotension (low blood pressure) are more susceptible to dizzy spells. For relief, take time to rest and slow your heart rate so that blood pressure can return to normal. Sitting with your head between your knees can help to bring oxygenated blood back to the brain.


Poor Breathing

During exercise our body’s oxygen needs increase. To facilitate these needs our breathing and heart rate increase so that adequate oxygen can be taken in and supplied to the working muscles. Breathing too shallow or too infrequently can deprive our muscles and brain of the oxygen they require and as a result can lead to dizziness. In an instance when this occurs it is best to rest and focus on slow, deep and controlled breathing. During exercise avoid holding or restricting your breath so you don’t become dizzy or lightheaded.


Overexertion

Overexertion happens when you push beyond your own physical capabilities. This can happen for a large array of reasons, maybe you’re new to training or starting a new program, maybe you’ve be unwell and you’ve gone back to training to soon, or maybe you’re at the other end of the scale and you’re trying to set some new personal bests. Overexertion can result in drop or spike in blood pressure, low blood sugar or even dehydration and as we’ve just discussed all of which can lead you to feel lightheaded or dizzy. Prior planning and preparation prevents poor performance so plan your meals, stay hydrated and remember that slow and steady progressions are all that is required in order for you to achieve your goals.


Exercise induced dizziness generally isn’t anything to stress about and can normally be avoided if your body is properly fuelled and hydrated. In some cases it can indicate and underlying problem with your heart or potential risk of diabetes. For this reasons it is recommended that you check in with you doctor if you’re experiencing frequent or severe dizziness.

xx Tara


Do you ever get dizzy when you exercise? Let me know in the comments section below.

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