Marathon FAQ: Question: I get light-headed and have trouble concentrating at the end of my long runs.

Answer: In investigating this condition among my runners, I’ve discovered that the most common reason for this is low blood sugar. In this case, increasing the blood sugar snacks, such as gel products or candy, can provide psychological relief. The general rule of thumb is to consume 30-40 calories per mile, with 2-4 oz. of water, every 1-2 miles. Most find that they need to start taking the blood sugar boosters about 4-6 miles into a long run.

Some of the light-headedness is due to fatigue. By taking walk breaks often enough from the beginning and starting more slowly, this problem can often be managed or eliminated. 

Jeff Galloway smiling near a lake with city skyline in the distance.
Jeff Galloway

Jeff Galloway, US Olympian and creator of the Run-Walk-Run method, has helped over 350,000 runners achieve their goals through his innovative training programs. As Runner's World's monthly columnist and author of North America's best-selling running book, Jeff has spent over 50 years sharing his expertise and continues to conduct running seminars worldwide as runDisney's Official Training Consultant.

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