Jim2's Running Page

Supplements and Bonking

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It is not "necessary" to use gels, bars and/or sports drink during a marathon to complete it. These products have only been available during marathons for the last 15-18 years. For 90 years before that, since the modern marathon was introduced to the running world at the 1896 Olympics, they weren't used at all, although some experienced runners did use such things as orange juice or de-fizzed Coke to supplement their race. However, the majority of runners simply used water. And many, many thousands of runners had very satisfying experiences during almost a century without such "necessities". I ran my first 5 marathons in 1983-84 with just water before sports drink first became available on the course in the 1985 MCM and all five were in the 3:35-3:54 range….not too bad for a mid-40's beginning runner.

Certainly, however, the advent of sports drinks and gels has been beneficial for marathoners. They provide a supplementary source of sugar which helps to conserve glycogen stored in your body and delays the point at which the body starts to rely primarily on fat for fuel....commonly known as "hitting the wall". However, if you race a marathon optimally hard, you will still touch the wall before finishing the race. The combination of race pacing and the use of supplements will determine when you reach it, how hard you hit it, and how well you deal with it.

One other comment about supplements....it isn't necessary, or even advisable, to use both gels and sports drink during the race. Use either, along with water, but not both. Using both can overload your stomach with sugar. That can be unsettling to some people and it requires the diversion of more blood from muscles to the stomach to digest it. Another way to look at it is that just because something is good for you doesn't always mean that more is even better. Too much of a good thing can be bad. How many times in our lives have we heard that "moderation" is the way to go? ;-)

Bottom line....supplements help, but they are certainly not essential. If they cause you digestion problems, then I would avoid them. If gummy bears and water work fine for you in your training LSD's, then go with that in the race. Gummy bears provide the primary component that sports drinks and gels do....sugar. They don't contain electrolytes as some sports drinks and gels do, but the benefit of electrolyte supplements during a race is controversial anyway. BTW, gummy bears are a favorite supplement for some ultra runners who can be on the course all day or longer. I know a guy....and old RWOL forumite (JC) from the 1997-99 era....who won the JFK 50 one year using gummy bears, orange slices and water….no gels or sports drink.

What is "bonking"? For all practical purposes, it is synonymous with hitting the wall.

Glycogen is stored in muscles and in the liver. When exercising, muscle glycogen is metabolized or "burned" for energy directly in the muscles in which it is stored. Liver glycogen is converted to glucose, which provides blood sugar for use by the muscles as a second source of energy.

The human body can store enough glycogen for about 18-20 miles of running. Using a sports drink, gels or other form of sugar can extend that distance. However, glycogen stores in both muscles and the liver are consumed during a marathon. As the body runs low on glycogen, it switches to using fat as a primary source of fuel with protein (muscles) as a secondary source. However, fat and protein don't metabolize as rapidly or efficiently as glycogen. Metabolizing them requires more oxygen than glycogen does….and the last thing a runner needs in the late stages of a marathon is increased demand for oxygen. The transition to relying primarily on fat is the point in a marathon when you can no longer generate the same level of energy and you begin to have more difficulty maintaining pace or, even, find that you can no longer maintain pace. That’s why a supplemental source of sugar in some form, such as in gels and sports drink, to be metabolized into glucose is beneficial.

Depletion of liver glycogen has another effect....it results in a "starved" brain. The brain can only use glucose for fuel. And the glucose it uses is generated from glycogen in the liver. When liver glycogen is depleted, blood sugar (glucose) drops, the brain becomes starved and you become mentally fatigued. That's when your brain begins to call you a fool for becoming a marathoner and insists that you will never run another one. ;-) As Glover says in his book, "The Competitive Runner's Handbook", "You feel lightheaded, uncoordinated, confused, depressed, unmotivated. Now, you not only can't run faster, you don't care." That's bonking!

BTW, you can actually bonk in a 5k or 10k race. No, you don't run out of glycogen stores in such a short race, so your muscles are still well fueled. However, it is very possible to run low on blood sugar. Most races are run in the morning 12 or more hours since your last meal. The intensity (pace) of short races often consumes glucose faster than your liver can generate it. The result is a drop in blood sugar and a starved brain.....a bonk. That's why it's a good idea to eat a high carb "something", like a power bar, a hour or so before even a short race to get your blood sugar level up.