This Is What Really Happens In Your Body When You Exercise

There's so much happening.

The human body is an incredible system capable of regulating itself and keeping all of its cells and tissues healthy and in balance. But exercising regularly is critical to maintaining that balance for overall health. 

Many people only associate exercise with calories, muscles, and fat, but there is so much more going on in the body. In fact, there are hundreds of hormones, enzymes, proteins, and chemical reactions happening while the body is physically active. 

Accounting for every single process that happens during exercise would fill several textbooks, but here's a brief overview of how the body responds to exercise:


Chemicals produced by the body during workouts:

Brain-derived neurotrophic factor (BDNF) - This is a hormone that interacts with the central nervous system. By tripling BDNF production with exercise, it is possible to improve mood, boost cognitive function, and improve memory. BDNF also contributes to repair of neurons and other housekeeping measures in the brain, which helps prevent neurodegenerative disease.

Cortisol - Exercise is pretty taxing on the body, and cortisol is a hormone released by the adrenal gland during times of stress. In order to help the body respond to the physical demands, cortisol helps metabolize carbohydrates into glucose for energy.

Glucagon - The body needs a lot of glucose to exercise, but sometimes the body has stores (like in the liver and fat cells) that aren't immediately available. Once the body is running low on glucose, glucagon works in these storage areas to help convert stored fat and sugar into a form the body can use as energy.

Human growth hormone (HGH) - Exercise puts a lot of wear and tear on the body, but the regrowth afterward is what creates that chiseled look. Intense exercise drives up production of HGH from the brain, which is needed for the repair of cells, muscles, and tissues. 

Insulin - Insulin is necessary to regulate blood sugar levels by helping glucose into cells to be used for energy or storage. As muscles begin to use up stored glucose during exercise, insulin brings stored glucose from the liver to where it is needed. After exercising, insulin will bring glucose back to the liver and muscles for storage.

Epinephrine and norepinephrine - These hormones are critical to the body's fight-or-flight response during stress, including exercise. Epinephrine is also known as adrenaline and helps increase blood flow to muscles for delivery of oxygen and glucose. Norepinephrine works to sharpen mental acuity, increase blood pressure, and decrease blood flow to the bladder and bowels. 

Lactic acid - Because the body is rapidly using up glucose for energy during exercise, the cells are making waste and byproducts faster than the body can get rid of them. While someone who is exercising might not be aware of all of the hormones and chemical changes going on inside their muscles, lactic acid is hard to ignore. When lactic acid builds up in active muscles, it creates a familiar burning sensation, signaling that the body needs a break.

What your body needs to recover:

Calcium - Exercise creates stress on the skeleton that causes a necessary process known as bone remodeling. Cells called osteoclasts help the body reabsorb mature bone tissue while osteoblasts follow behind to create new immature bone cells. Calcium is an essential component that makes those new bone cells hard, giving the skeleton support. 

Calcium can be obtained in dairy products like milk and cheese, as well as green vegetables like kale, broccoli, and spinach.

Chloride - Though only small amounts of chloride are lost during exercise, it is essential for maintaining the body's pH and fluid balance. It is also an important component of the enzymes that digest proteins and aid in the absorption of certain nutrients. Chloride deficiencies are not common, but can result in extreme fatigue and dehydration.

Chloride can be replaced with regular table salt, but it is important not to overdo it, as chronic high levels can lead to hypertension and heart failure. 

Magnesium - Magnesium is essential for hundreds of processes throughout the body, including building proteins, immune function, regulating heart rhythm, muscle function, nerve conduction, and much more. Like chloride, magnesium is lost in small amounts through sweat during exercise.

Good sources of magnesium include spinach, almonds, cashews, and peanuts.

Potassium - Potassium is another mineral lost through sweat. It is crucial for the body's pH balance, building proteins, breaking down carbohydrates, muscle growth, and more.

While bananas are the most popular source of potassium, other good sources include salmon, broccoli, and potatoes (with the skin on).

Sodium - While sodium sometimes gets a bad reputation, it is a critical component for muscle activity, nerve function, and regulating blood pressure. When sodium levels get low, muscle cramps and dizziness are common. Large amounts of sodium are lost during exercise due to sweat.

The good news is that replacing sodium is easy, as it is found in table salt. Just like chloride, however, overdoing it can be bad for heart health.

Most people are able to fulfill their nutrient needs through their diets. But if there are needs that aren't being met, a supplement is a good way to fill in any gaps that might exist and can easily be picked up at your local Walgreens. As a bonus, vitamins bought at Walgreens help provide vitamins around the world for those who need them most, thanks to the Vitamin Angels program. 

Cover image: Shutterstock


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