In light of the recent marathon tragedy, I wanted to share with everyone some thoughts on supplementing during marathons and endurance events. This conversation comes up frequently and just last week a friend had asked me about energy gels in regards to the calorie content and specifically how much potassium it contained. My response was the information of the caloric content (which basically means nothing more then the volume of glucose you’re ingesting) and that no one should care about the content of potassium. Our bodies can regulate potassium. We do not need to ingest excessive potassium unless we have a deficiency in the ability to regulate our potassium which is common in those with renal disease, or those who take diuretics. It is not a concern of endurance runners, assuming you are eating a healthy diet. If you’re not eating healthy, then you shouldn’t be running a marathon and instead focus on eating healthy and not running. When your body is unable to regulate potassium, it leads to cardiac arrhythmias which can be fatal. In this particular case, the runner has a potassium level that was 3 times the normal value. So he was regulating adequately, but the possibility of over ingesting caused his potassium levels to become fatally high. This can be combined with the ischemic bowl that occurred from is colon issues which were probably related to over ingesting ibuprofen. Ibuprofen can lead to bleeding in the stomach and intestines. In this case 75% of the blood flow to his colon had stopped which will also interfere with the body’s ability to regulate potassium because absorption from the colon is stopped.

What happened is very rare, and in my opinion from what is known so far, is probably more related to the ibuprofen’s long term effect on colon which lead to bleeding and created an ischemic bowel (absence of blood) leading to the fatal levels of potassium in the blood.

What I would like to stress here is what concerns endurance runners should focus on.

Hydration

Hydration needs to occur ALL THE TIME. Everyday. Not just during the marathon, or the morning of the marathon. Chugging a glass of water the morning of will not help you as much as it will to stay consistently hydrated all week long by drinking until your urine is clear regularly. Be careful with over hydrating with sports drinks. You can actually induce dehydration of the body by ingesting too much sports drinks, gels, or “energy supplements”. When ingested, this increases the osmolarity (concentration in the colon) which will shift water into the colon resulting in an induced dehydration.
NaCl (salt)

NaCl comes from multiple sources and our body also does a great job of regulating it naturally. What most people need to know, is how you become deficient in salt. Think back to physics class and remember the concept of concentration of molecules. Our body has a set volume of fluid or blood and within it is a unique concentration of NaCl. There are two ways you can disrupt this concentration of NaCl. One way is rather obvious to most people and that is by sweating and losing NaCl in your sweat. We can only produce so much sweat to cool our core temperature off before we start to lose water or become dehydrated. Within the sweat that we lose is NaCl. With too much sweating, as what occurs during long sustained activity in the sun or humid conditions, we lose NaCl. This needs to be replenished after a given period of time which is most easily done after a race by ingesting more salt in your foods and the body auto regulates. During a marathon one probably would need to replenish the NaCl faster by ingesting sports drinks such as Gatorade or something similar. Salt tablets should be reserved for extreme temperatures and high humidity and only after a long period such as 2-3 hours of running. Another way of becoming low in NaCl is by over hydrating with water, and diluting your body’s current concentration of salt. If your not losing water and your drinking too much, this can happen. Something else to consider is if you lose too much NaCl through sweating and you over hydrate on water only, you again increase the risk of lowering e NaCl concentration.

K (potassium)

As I have mentioned above, there are only a few common ways of depleting potassium otherwise know as hypokalemia. Taking diuretics, kidney disease, abusing laxatives, and excessive vomiting can lead to depletion of potassium. Gastric outlet disruption, which can be caused by chronic bleeding as with a peptic ulcer (most likely what led to this marathoners problem) can also cause hypokalemia. Running in itself will not lead to a depletion of potassium.

The important take home points from this is our body has a wonderful mechanism for controlling the chemicals and electrolytes it needs to function. Presuming you eat a healthy diet of whole foods that are not processed (ie fruits and veggies) then you are most likely not deficient in any vital nutrients or electrolytes. If you do have an illness that reduces your intake of foods or water, or you begin vomiting excessively during a run, then you probably should not run or stop running.

When in doubt let your body regulate itself, rely on the natural thirst and hunger mechanisms, and if your feeling bad, stop.

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