Hitting the Wall, Part 2

In part 1 of this series I shared an example of hitting the wall from the Chicago marathon 2004. My pace slowed down nearly 50% near the end of the 26.2 "race". I ran out of energy, despite my attempts to fuel with Gatorade and Gu during the race, pasta-loading days before the marathon and tapering (reducing mileage) in the last few weeks to conserve fuel. And besides the carbo-loading, I also trained at an aerobic pace to encourage fat metabolism, even though I was consuming all those carbs.

And I repeated this strategy over and over. My last marathon experience in November 2010 was so miserable that Barefoot Josh gifted me a sculpture of "The Scream". Well, the plethora of those Nashville hills and barefeet on rough pavement contributed to my negative outlook, but my pace and energy levels dropped so low...I don't know how I finished really. So you know what they say about the definition of insanity. Try something different. Actually, I've toyed with the idea of giving up marathons.

Until about a month ago, I stopped running completely for several months while waiting for an ab pulled muscle to heal. That was a result of excessive, aggressive crossfit exercise in January. I experienced a few pounds of average weight gain in the first month of inactivity, so I decided to change my nutrition. I discovered Mark Sisson in a chapter of the book "Run for Life" by Roy Wallack. Mark was described as an ex-marathoner/triathlete who endorsed minimal exercise and a paleo approach to nutrition. This photo in the book of Mark's 6-pack motivated me to check out his site Mark's Daily Apple to learn more.


Mark is a prolific writer on the topics of nutrition, exercise and overall wellness of life. Very specifically, though, his posts on chronic cardio really resonated with my recent gloomy view of marathon distance running. One of his chief complaints is that the "mid-high level aerobic work requires large amounts of dietary carbohydrates", which doesn't comply with the primal/ paleo/ low carb-high fat nutrition plan. "Why low carb?" you may ask. Because carbs elevate blood sugar concentration which increases insulin levels which store those carbs as fat. Too many carbs make you fat. So I followed Mark's "Primal Blueprint" starting in March. I tracked my nutrition which consisted on average of calorie basis of approximately:

• 15% carbs
• 25% protein
• 60% fat

I was consuming on average 65 grams of carbs daily and about 2000 calories daily. I lost about 10 pounds in a few months, with only exercise from walking. Now I am starting to run again, though, since the ab muscles has healed after 4 months. Should I continue this nutrition plan as my endurance exercise levels increase? A similar question was asked of Gary Taubes at Authors@Google (author of "Good Calories, Bad Calories" and "Why We Get Fat") when he was asked to address carbo-loading for endurance athletes. He replied that he isn't an expert in this area and referenced Dr. Stephen Phinney's low carb exercise research, who is now an emeritus professor of nutrition at UC-Davis. Gary Taubes said Dr. Phinney disagrees that endurance athletes need to carbo-load.

Dr. Phinney was recently interviewed on Jimmy Moore's "The Livin Low Carb Show", and discussed diet and exercise in combination. He used himself as an example to describe the effect on exercise from switching from a high carb to low carb diet. On a high carb diet and riding his bike for 1.5 hours, he would need to take along a few bananas to fuel up during the ride and after the ride would immediately eat from hunger. On a low carb diet his body is what he calls "keto-adapted". He doesn't eat anything during that 1.5 hour bike ride (drinking only water) and eats less afterwards (less hunger). He said his body has improved fuel flow (generating ketones for fuel, not depleting them). He doesn't experience discomfort (low energy) during the exercise because he is not compromising his body's fuel reserves. Even as a relatively lean person, he has plenty of fat reserves, and his body is habituated to using them.

In Dr. Phinney and Dr. Volek's new book "The Art and Science of Low Carbohydrate Living" chapter 6, "Basic Human Energetics and Fuel Partitioning" describes bonking (aka "hitting the wall") and that it can affect even those people who do not do intense exercise, but at a slower process. Their discussion is concluded by the following:

This adaptation to carbohydrate restriction is facilitated by sharply reduced insulin levels and takes a few weeks to be fully implemented. Once keto-adapted, the body can maintain its lean tissue composition on a moderate protein intake and sustain prolonged physical exertion using fat as its predominant energy supply.

In part 3 of this series, I'll take a closer look at Dr. Phinney's research on low carb exercise.