If you’ve been unfortunate enough to fall behind on fueling in a race (I’m included in this crowd, too), then you know it’s no walk in the park. It’s possible for this to happen at any race length really, based on factors like how you fueled going into the race to race-day environmental conditions and how you fueled during the event.
So is there anything that can be done to salvage the day? Let’s take a look at the symptoms and possible solutions.
Symptom: Bonk-like fatigue (aka “hitting the wall”)
Problem: You’ve run out of gas – literally. At least the quality kind. The experience of bonking usually occurs after muscle glycogen and liver glycogen (the only stored carbohydrate sources) have been depleted. Now your body is trying to reformulate glucose (in a process called gluconeogenesis) to keep up with demand and use more fat for fuel. Unfortunately, fat is burned aerobically, so your body is forced to slow down.
Solution: First, be sure to enter the race with adequate carbohydrate stores and maintain adequate intake during the race. Once you’ve fallen behind, catching up is almost impossible. There is some possible performance benefit via the central nervous system just by having carbohydrates in your mouth, however for carbs to have any impact on blood sugar or muscle glycogen it would take 15-30 minutes. In the meantime, you’re still trying to move forward. If it’s towards the end of a race you’ll likely just have to push through; if you have a ways to go, it may be worthwhile to slow down for a bit (even walking) to try and consume an easily digested carb source such as sports drink (but don’t drink so quickly you cause gut distress.)
Symptom: High heart rate, slightly dizzy and faint, weak
Problem: It’s likely dehydration. As your blood volume reduces, your heart has to work harder to keep your blood pressure appropriate for blood flow. Overheating and cramps may occur. You risk passing out if blood pressure drops so low you can’t get enough blood flow to your brain (for example, if you stop to bend over and take a breath then stand up and get dizzy.)
Solution: Once dehydrated it is very tricky to go in reverse while still racing, and dehydration can be quite dangerous, in particular in hot conditions. You will likely have to slow down and start consuming fluids which contain both water and electrolytes. A sports drink has a good combination for the best digestion and absorption. Once dehydrated, consuming solid foods or highly concentrated carb sources (like a gu without water) may end in debilitating gut problems. Without the appropriate hydration and electrolyte status, digestion will be slowed.
Symptom: Nausea, bloating, weak
Problem: Could be several different things, but if you feel like you keep trying to fuel but nothing is making it past your stomach, it could be dehydration or hyponatremia.
Solution: This one is tricky. Hyponatremia occurs when the sodium concentration in your blood decreases or becomes diluted. Most think hyponatremia is only a result of drinking too much plain water; however, it’s possible to both be dehydrated AND have low sodium levels. Drinking more water wouldn’t be the solution as you will only dilute the sodium more, and a regular sports drink may not be enough electrolytes. Additionally, digestion will slow given the change in electrolytes. Hyponatremia is dangerous and can lead to altered cognition and even coma. If you experience these symptoms it’s best to seek medical attention – an IV will likely be needed.
Bottom line, fueling during a race isn’t just about performance – it’s about health and safety, too. Many of the same symptoms can occur for different problems, so if in doubt check with the medical tent at the race. And if you do have an under-fueling experience, be certain to learn from it for the next time!