What is salt loading? 

Salt loading using salt supplements is the process of consuming additional electrolytes in the form of salts prior to an athletic event. These electrolytes hold on to additional water via intracellular water retention. This helps the muscles contract with less effort for longer. The additional salt helps your blood maintain enough water to keep it flowing optimally and filtering through the kidneys. 

Why salt load?

For events where you will sweat for a long period and are going to struggle to reabsorb enough electrolytes during the event, salt loading can provide you with a significant performance boost and make the race safer.  

If you sweat out too many electrolytes (sodium, potassium magnesium, chloride and calcium) and do not replace them you can suffer from: 

• Cramps 
• Fatigue 
• Nausea 
• Swelling around the legs and eyes 
• Dizziness 
• Pain in the kidneys (lower back) leading to Acute Kidney Injury (AKI) 
• Fainting 

Given most of us get enough salts through our normal diets for shorter endurance events, a good barometer is that if the event is more than 90 minutes in length you can start thinking about salt loading before the event. For a shorter race in a moderate climate, it may only be necessary to have one additional serving around 5 hours before the race and then just add one or two servings to your water bottle on your way around. 

For longer events 6 hours or more or if you are in significant heat you can take 2-3 servings before the event. Your body can only process electrolytes at a certain rate, so having the extra salts before means you can maintain an electrolyte balance to assist with performance much later in the race.  Again you can top up levels during the event.  

For more information about getting enough salt during the event read our dedicated article.

The science behind salt loading 

Your body removes water from your body by filtering your blood through your kidney. This requires a balance of electrolytes (especially sodium and potassium) to pull the water across the membrane wall from the bloodstream into a collecting channel in the kidney. This process uses the electrolytes which must be replaced.  When you are doing an endurance event this process is accelerated. If you do not have enough electrolytes the osmosis to pull the water into your kidney this slows down. Not processing the water can be dangerous, especially if you are consuming more liquids during the race.    

Salt loading helps you prepare your body for an event by tilting the balance of salts higher so that you have more to fall back on during the event.

Managed decline 

The aim for endurance athletes (as opposed to athletes trying to optimise performance over much shorter periods) is really managed decline. How fresh you are in the latter stages of an event can make a big difference to how you place for a competitive athlete, or for the amateur, how much you enjoy it and how quickly you recover. 

Starting with an excess of salts and topping up along the way allows you to manage this decline. It means that you are not cramping, and you can worry about the blisters! 

How much salt to have and when? 

Salt loading is very personal. The size of the athlete, if they are a heavy sweater, how recovered they are, if the conditions are very hot or humid, the length and severity of the race, the expected finishing time and even the number of refuel stations will all play a part. 

It is best to start loading salt the day before. You can have one serving around 24 hours before. This ensures you have processed the electrolytes and you are not trying to force feed yourself salts just before the race. 

Depending on the length of the event, I like to have another 1-2 pre-race servings just spread out on the day of the race.  One word of warning, salt loading can give you a bit of a headache. If you get a very mild headache, this means you should stop loading and are probably at the top end of your loading capability. If it is an extreme headache then you have had far too much.   

Know yourself before race day

This should go without saying, but you don’t want to be playing with variables on race day that you have not understood before.  In the same way, as you would not wear brand new shoes you don’t want to be playing with aggressive salt loading protocols. 

Using salt loading during training means you can gauge how much you can have before the event, your requirements during the event and what impact other variables can have. 

Signs you should have had more salts after the event 

If you have done a very significant event (8+ hours), get home, and then wake up multiple times in the night to pee. This means you didn't have enough electrolytes to process all of the water you took on board. Normally people eat a proper meal at the end, this often has a lot of salts which allow you to start processing the water. Believe it or not, you were probably on the road to being in some difficulties. 

Backache during or after the event. This is your kidneys crying! When they don’t have enough salts to keep the electrolyte balance in your blood right, they can’t process the water. 

You finish the event more than 2% lighter than when you started. Everyone finishes lighter, it's how much lighter that matters.  

As you can see salt loading is very important for sports performance and recovery.  Check out our electrolyte SALT!