After a few days on the trail, sled dogs burn nearly
100 percent fat fuel. Could people train to do this?
See "Fat Burning Secrets..." from the Smithsonian.
Photo credit: cliftonmullins from morguefile.com

A few decades ago when runners talked about "hitting the wall" it was just one of those things you expected on a long run. After about 15 miles you'd suddenly feel like crap and be so weak you'd think you were unable to continue, but then you'd dig way down if you were brave enough and find renewed strength by sheer force of will, and you'd keep going.

All that talk about reaching deep for the buried strength within you and mentally being strong enough to continue on will alone seems now to be mostly egotistical talk. When muscles reach a specific level of exhaustion the autonomic nervous system shuts them down so energy stores won't completely be used up. Will has nothing to do with that, it's biological self-preservation. If you push yourself to your limits you'll find that point. One second you'll be plugging along full of determination and the next second your body tells you, no, you won't, and you stop. After a few minutes of rest you keep going.

People in higher levels of fitness reach their limits less often, and everyone's energy cutoff point is different, but it happens to all. When you run long enough to burn up your blood sugar and muscle glycogen, you "hit the wall." Suddenly you can't put one foot reliably in front of the other or run a straight course, and then as your metabolism shifts to fat reserves you gain renewed strength and recover. If you're an egotistical person taught to believe in mind over matter, you realize you've conquered a physical weakness by an effort of will. Actually your liver just kicked in and took a moment to start processing fat.

The fuel system of the body is actually much more complicated than that simplified version, but that's enough to understand what's happening in a practical way. Exhaustion at the limits of ability is set at a cellular level. Mitochondria in cells enable us to use fat, the body most efficient fuel, and our ability to do that depends on the numbers of mitochondria in our cells. That population of tiny furnaces increases if we frequently engage in long-duration physical labor, whether it's farm work or distance running. The more mitochondria you build, the better you are at burning fat. For someone in a lower level of fitness, a food that replaces blood sugar could make the best sense; since over the short term, with a lower mitochondrial count, the body prefers to burn sugar. As conditioning improves, the best fuel choice changes to a mixture of sugars and fats.

Dr. Eric Heiden, Olympic gold medalist and orthopedic surgeon, says that a mixture of glucose and fat feeds the fires of highly conditioned athletes, and you can see that reflected in the traditional tonic foods of ancient travelers. Pemmican, the food of choice when Native Americans set out on long treks, blends dried berries with rendered animal fat -- a source of carbohydrates and fat and very little else. The Tarahumara charge up with complex carbohydrates like potato soup and corn beer, but the trail tonic they drink along the way is a mixture of chia seeds, citrus juice, and sugar -- again, carbs and fats, since chia contains a high percentage of healthy oils, similar to those found in salmon.

Chia also replaces some important minerals which the body loses through perspiration, provides protein, and contains important vitamins. Chia tonics seem like a better idea for the long run than fat with dried blueberries, but pemmican represented only part of the traditional food plan here in northern America. Travelers grazed fresh vegetables and fruits along the way, eating plants most of us would skip today.

From Europe comes another story of a traditional powerhouse food for the long-distance foot traveler -- flaxseed. The nutritional content of flax closely resembles that of chia and even exceeds it in some mineral levels and in total fat content, yielding the same healthy oils as chia. The Roman Legion, according to many historians, fed their troops bread made from wheat, rye, and flaxseed. Roman soldiers were well known for their endurance and their strength in combat, able to march long distances without exhaustion. A normal day's ration included 1.5 kilograms of whole grains including the secret ingredient, flaxseed.

Another important benefit of both chia and flaxseed is that these tonic foods counter inflammation problems -- that reduces pain and helps runners keep going.

Today most of us avoid fat in order to keep body weight down, but during heavy exertion fat doesn't go through the storage cycle. Cells use fat in the bloodstream along with blood sugar, saving the body the extra steps of storage and retrieval.

Having learned all this fairly recently from researching several fitness articles for a paying client, I find it interesting to compare my own traveling diet to what traditionalists and sports professionals recommend. I've been a hiker and runner for decades, actually quite a few decades, and I've spent my work time primarily in labor-intensive occupations. I've learned to eat what keeps me going, and if a meal's fuel doesn't last past 9 a.m. I'm not happy with it. I don't eat breakfast at Shoney's if I have work to do.

My typical breakfast is a whole grain with fruit when I'm backpacking a difficult trail. For convenience I usually eat instant brown rice -- the secret fuel of the samurai with a modern twist -- and raisins. That's a healthy mixture of long-lasting complex carbohydrates and fast-acting fruit sugar. On the trail I don't get extremely hungry during the day, but I do fuel up along the way with a Tiger's Milk bar when I feel the need -- complex carbohydrates, sugar in a reasonable amount, minerals and vitamins, protein and fat. Supper is usually instant potatoes with Parkay margarine, a bouillon cube and a vitamin pill, as well as some dried meat or fish. During the day I graze wild food along the way. It doesn't sound like much but it makes me feel good. When I'm on the trail I'm just not hungry for anything else. Traveling food is fuel, not entertainment. My trail diet matches up very well to what ancient travelers discovered worked the best for them.

As a runner I've had more trouble, depending on modern professionals for advice and drinking energy drinks or power gels to keep charged on the runs. I don't find that such things work well for me. They give me a short burst of renewed energy and then I'm back to being really tired. This year I'm going to apply the traditional foods to my long runs and see if I find an improvement.

I also rebuilt my huaraches, using some tips from the Tarahumara, who build their running sandals out of old car tires. See my post about Shoe Goo on The Marked Tree for construction details using lighter materials. That works like a charm.