Running a marathon is not just mentally intense. Running 26.2 miles straight is one of the toughest physical challenges as well. Here are 10 things that happen to your body when you run a marathon:

1) High Calorie Burn

Expect to burn 10 times more energy running a marathon. The average female runner burns around 2,300 calories during the 26.2 miles, according to Shape.com.

2) Temporary Weight Loss

Marathoners drop 4 to 10 pounds through fluid loss during a marathon. That fluid equals from 1 to 1.5 gallons of sweat! That is why it is important to drink about 500 ml per an hour during and after the race to maintain your fluid balance.

3) You Shrink

Marathoners can finish the race around 2 centimeters shorter than when they started. GettheGloss.com said that this shrinkage is caused by fluid being lost between the spine’s intervertebral discs. Your height returns when you refill that lost fluid, usually 24 hours later.

4) Chafed Skin in Sensitive Areas

Bloody nipples are one such area. Ouch. Sometimes our clothing, movement and sweat work together to rub skin raw.

Runners may notice chafing along the elastic parts of their sports bras. It can also happen around the ankles, armpits and inner thighs, according to Today.com.

5) Hyponatremia

Hyponatremia can happen when you drink too much water while at the same time, are sweating way more than normal. The result: a precariously low amount of sodium in your blood.

Today.com warned that women are more vulnerable to hyponatremia because their bodies are smaller.

6) Blisters, Sore Feet and Toenail Loss

Your feet run about 33,000 steps during a marathon, according to Shape.com. That mileage takes its toll and causes blisters and soreness. Toenails get hit hard too. Many runners say toenails can turn black and fall off.

7) Damaged Blood Vessels

All that running compresses the tiny blood vessels in our feet from the impact. This reduces levels of oxygen-carrying red blood cells.

8) Brain Boost

One study found that running improves both short and long term memory. It also helps foil the type of memory loss connected with being incredibly stressed out.

9) Higher Core Temperature

By the time runners finish the marathon, their core temperatures have increased two to three degrees.

10) Upset Stomach

Our bodies can shut down digestion in order to send that energy to our legs. As a result, 50 percent of marathoners report some kind of upset stomach during a race, reported Shape.com. That upset stomach can be accompanied by cramps, diarrhea, heartburn or nausea.

A final note, your stored energy levels are normal after about a week. Any muscle damage heals in around 14 days.

Now it’s up to you to decide if running a marathon is right for you.

Reviewed June 17, 2016
by Michele Blacksberg RN
Edited by Jody Smith