How Do Your Bodily Functions Alter During Hot Weather?


In general, the human body is pretty amazing at multi-tasking. Some of us can even rub our stomach while tapping the top of our head – hats off to you people, hats off. However, when exercising, especially during hot weather, our body has to prioritise some functions over others.


The fight occurs over our blood volume. The muscles require oxygenated blood as fuel to keep them going. The skin wants blood to get rid of excess body heat. Sweat glands pull fluid from the blood plasma to create sweat. And your gut needs blood flow to move nutrients into the body that can then be converted into energy! If you’ll excuse the pun, it’s a real blood-bath in there.


When push comes to shove, the body’s cooling mechanisms win this round. Temperature regulation trumps fuel for the muscles, and both are prioritised over food digestion. So, believe it or not, digesting our precious food is definitely not top priority in hot weather. That’s why if you’re dehydrated and overheated and there isn’t enough blood volume to go around, your gut slows or stops digesting food, and you aren’t able to attain the nutrients you need. In the heat, inertia in the gut often leads to nausea and GI distress, which are leading causes for DNFs in ultra-endurance events.


Therefore, the bottom line is that your ability to function in the heat is highly dependent on your hydration status.


Hydrating through fluids:


Of course, an obvious way to ensure hydration is through the consumption of liquids. The amount of liquid each individual requires to stay hydrated varies, as does the amount an individual will sweat. As a result, there is no single recommended volume of fluid to take on, but a good way to measure whether you are properly hydrated is to monitor your urine – if it is light yellow then bravo, you’ve taken on sufficient water. But if it’s dark and stinky, take a drinky! For more information on hydration see our previous post, 10 Signs you may be Dehydrated.


Drinking water is normally sufficient to remain hydrated, but if you’re training for 60 minutes or longer, it may be wise to consume sports drinks alongside water in order to help replenish any lost electrolytes.


Hydrating through food:


Food is often overlooked as a source of hydration, but on average it provides roughly 20% of our daily intake of fluid. Seeing as digestion is not the body’s main priority when training in the heat, try to focus on incorporating foods into your diet that are easily digestible and contain a high water-content.


  1. Melons: made up of 90% water; an ideal recovery snack.
  2. Berries: contain up to 92% water and are rich in anthocyanins, which help to reduce post workout inflammation and joint pain.
  3. Grains: quinoa, rice, oatmeal – they soak up water while cooking, which your body absorbs in digestion.
  4. Capsicums: 92% water and packed full of Vitamin C!
  5. Iceberg Lettuce: leads the way at 96% water!
  6. Celery: 95% water and high in fiber.


There are plenty more foods that act as good hydrators: apples, kiwi, grapefruit, coconut, bananas, spinach, cabbage, broccoli, and vegetable soup. Energy gels are also popular to consume during the exercise itself because they are easily digestible and contain-fast acting carbs and sugars to provide an energy boost.


Salt replenishment:


Finally, with an increase in sweating comes an increase in the amount of electrolytes lost. One such electrolyte that is crucial to replace through diet is sodium (or salt), and the consumption of the average sports drink post-exercise is not necessarily sufficient to replace lost sodium. In fact, the sports drink would most likely have to taste more like seawater than a sweetened beverage to achieve adequate sodium replacement!


This isn’t to say add a bucketful of salt to every meal! But if you are training hard during hot weather, and especially if you are leading up to a big race, try to eat plenty of high-sodium foods such as salted nuts or pretzels, or smoked, cured or canned meat, fish or poultry.