In the last article, we discussed the vital importance of pre-race nutrition to build up the body’s store of glycogen, vitamins, and amino acids. We also discussed the fact that after several hours of continuous exercise, the body diverts blood away from the digestive system to keep the muscles oxygenated and processing glycogen. Therefore, it follows that nutrition during an extreme endurance event becomes a delicate balance.
Prior to digging into the nutrition side, we definitely want to hit the hydration issue briefly. Water is essential, and without proper hydration management an ultra–runner is in real danger of injury or even death. Hypernatremia (dilution of the electrolytes in the bloodstream due to drinking too much water) and Dehydration (not drinking enough water) are both serious threats. Managing these two conditions is unique to each individual and requires some experience to get right, from “drinking to thirst” to “a liter per hour minimum”, but suffice to say… get it right.
From a nutritional standpoint the first few hours of a 100 mile run are critical, as the blood supply to the digestive system is still at a more-or-less normal level and the body is still capable of effectively making use of calories consumed during that time. It’s this first four to six hours that taking in high-calorie, highly digestible food sets the stage for success later on in the event. The body isn’t storing anything at this point, but it’s consuming and burning these calories in preference to stripping glycogen from the muscles themselves, and thus is preserving those reserves for later on.
After the blood supply starts to leave the digestive system resulting in its subsequent loss of digestive efficiency, the timing game really begins. An athlete must monitor their system closely, often pushing just to the point of nausea and then backing off to let their digestive system recover. Occasionally, an athlete must slow down or even stop just long enough to trick the body into re-establishing blood flow to the digestive system. Highly trained ultra-runners have the ability to keep their exertion right at the pre-nausea stage, and can literally fly along the trail taking in just gels, small snacks and electrolytes every hour or so. However, highly trained or novice, getting behind on nutrition has immediate and dramatic results.
A personal experience illustrates this well. After the first six hours of the 2012 Wasatch 100 my watch died and I no longer had my 15 minute reminders to eat a bite or take electrolytes, and hydrate. I was focused on running, and I went about two hours without nutrition or electrolytes only awakening to that fact as I saw the next Aid Station coming into view, and realizing my stomach was in knots. Rather than stopping at the aid station and letting my system re-gain normalcy before heading out, I made a quick pass through the aid station and continued on. This decision ended up costing me the event, as the next several hours were filled with active emesis which in-turn kept me from maintaining nutrition and hydration. I was done by 53 miles; a DNF in a race I’d trained a year for.
One very experienced ultra-runner I’ve talked with about this subject has often had days where his body was exceptionally sensitive to getting off-balance during an event, and he has gone to the extent of even laying down right on the side of the trail for 20 minutes or so to let the blood supply return to his digestive system. Then he’d eat some chews or gels, and slowly start off again, building back to race-pace slowly over the next 20 minutes. In one 100 mile event last year, he stated he’d did this 3 times, and still finished in the top 10.
Extreme endurance events push the human body to its limits, and sometimes beyond. Finding the perfect balance between nutrition and exertion during endurance events is a process that will take the better part of a career, but as each athlete narrows down that balance (and learns to listen to and obey their body) they’ll have much better results on race-day.