Photo courtesy of Mike Warren

Athletes have been practicing carbo loading since the late 1960s. But what’s the big deal with carbo loading? What the heck is it? Why do it? What are the benefits?

The short answer is that carbo loading enhances endurance performance by increasing the amount of glycogen in the body. More glycogen (Carbohydrates) stored in the muscles and livers equates to more energy at an athlete’s disposal.

The benefit? You’ll last longer in an extended endurance event!

In practice the body normally has enough Glycogen for events up to 90 minutes in duration. But if you are doing an extended event like a Marathon, there are some obvious benefits to extra glycogen stores.

So how does one carbo load? There are various carbo loading practices, which have changed over time with new Scientific findings. These are elaborated on at great length in an article I discovered the other day titled The evolving art of carbo-loading.

A Swedish physiologist named Gunvar Ahlborg was the first to introduce some scientific basis to the fact that the muscles and liver are able to store above-normal amounts of glycogen when high levels of carbohydrate consumption are preceded by severe glycogen depletion.

The stress of severe glycogen depletion triggers an adaptive response by which the body reduces the amount of dietary carbohydrate that it converts to fat and increases the amount of carbohydrate that it stores in the liver and muscles as glycogen -a phenomenon Ahlborg referred to as glycogen supercompensation.

From his findings he developed The Ahlborg method:

Perform an exhaustive workout one week before a long race (90 minutes-plus).

Consume a very low-carb diet (10%) for the next 3-4 days while training lightly.

Consume a very high-carb diet (90%) the next 3-4 days while continuing to train lightly.

Endurance athletes around the globe began to use Ahlborg’s carbo-loading plan prior to events anticipated to last 90 minutes or longer.

While it worked, it had its share of drawbacks. Many athletes weren’t keen on performing an exhaustive workout just a week before a big race. Also maintaining a 10 percent carbohydrate diet for three or four days carried some nasty consequences including lethargy, cravings, irritability, lack of concentration and increased susceptibility to illness.

Fortunately research later offered an alternative method that increased glycogen storage without first depleting it.

The no-depletion method came onto the scene:

Perform a long workout (but not an exhaustive workout) one week before race day.

Eat normally (55-60% carbohydrate) until three days before a longer race.

Eat a high-carb diet (70%) the final three days before racing while training very lightly.

The method was more pleasant to athletes and carried fewer of the risks associated with the Ahlborg method. Athletes were no longer required to perform a long depleting workout a week before a big race!

However, in 2002, however another method was devised by scientists at the University of Western Australia. This was perhaps the easiest method of all to follow as it only involved one day of preperation:

During the pre-race week, eat normally while training lightly until the day before a longer race.

On the morning of the day before the race, perform a very brief, very high-intensity workout. (In testing this consisted of two and a half minutes at 130 percent of VO2max (about one-mile race pace) followed by a 30-second sprint).

Consume 12 g of carbs per lb. of body weight over the next 24 hours.

The result? A 90-percent increase in muscle glycogen storage!

The method works best if preceded by a proper taper - several days of reduced training with the purpose of rendering your body rested, regenerated and race-ready.

So when should you use Carbo Loading?

Carbo-loading in general has been shown to enhance race performance only when athletes consume little or no carbohydrate during the race itself. If you do use a sports drink or sports gels to fuel your race effort - as you should - prior carbo-loading probably will have no effect. But it doesn’t hurt to do it anyway, as insurance.

Article Link:

• The evolving art of carbo-loading

Technorati Tags: Carbo Loading, Diet, Performance

By Ramzi
The question was raised in the Ask the Running Doc section of Runners World: Should use gels or Gu every 45 minutes as well as sports drinks for energy in my first Marathon?

Dr. Lewis G. who Runner’s World claim is the “world’s premier running physician” certainly seems qualified to answer this question with an impressive list of credentials including: medical director of the New York Road Runners, the ING New York City Marathon and all of Elite Racing’s Musical Marathons, The Leukemia & Lymphoma Society’s Team in Training program and he also serves as Chairman of the Board of Governors on the International Marathon Medical Directors Association.

The Doc advocates “real” food over gel or GU packets:

If you were at a barbecue on the weekend and on the buffet was barbecued chicken, salad, and lots of other “real” food, or an iced bowl of gel or Gu packets, which would you eat? Of course you would go for the real food. I absolutely prefer, without a doubt, smart food choices during your training and on race day

Dr. Lewis also advises that you should try nothing in a big event that you haven’t tried and tested in your training:

[you should be trying] nothing new (including food and or drink) on race day that you haven’t done in training. You should be drinking a sports drink and doing the salt in training as a prep for race day, as I’ve said in previous blogs.

On the overuse of gels and Gu, the Doc is critical of the high sugar levels offered by the supplements:

Overuse of gels and Gu, I have found, makes my runners and walkers not feel as well on long runs or half and full marathons. Whenever the body “sees” a high sugar load, as is in these products, there is a rise in sugar, followed by a rise in insulin which causes an abrupt drop in sugar. Doing this over and over again, every 45 minutes, gets you what we call the “yo-yo effect” and by the time you finish, your body is just plain worn out.

Generally what happens if you load up on simple sugars (which gels and Gu are loaded with) is the body is immediately charged with energy and you feel really good, but then insulin levels in the body rises which causes an abrupt sugar plummet - which drops you in a hole! This “crashing” effect is certainly not what you want in a Marathon.

The Doc states that scientific evidence has shown that if you take in a sugar load only once at “the wall” or about 17 miles/27 km you’ll increase your sugar enough to finish feeling strong.

This controversial post has certainly generated plenty of debate and flies in the face of what is recommended in many other articles and sources. But you must wonder if this is due to the massive market for supplements. Of course the manufacturers want you believing you should consume their gels as often as possible.

On the other hand the Doc’s comments strike me as a bit vague and leave a lot of threads hanging.

Admittedly it’s been a while since I read any literature on this topic myself, but my understanding - at least for the elite marathoner - is you should drink a low-concentration energy drink formula, frequently throughout a Marathon. As I recall, the Marathon is also the only race where this applies, any shorter distance and you naturally possess enough energy to carry you through to the finish line. This might not be true in all cases however.

While Dr. Lewis clarifies the frequency of fueling (at least in his opinion), he does mention the type of fueling. Presumably he is not a fan of gel/Gu products. He does not state if this intake at the 17 mile mark should be gels, Gu or another type of sports drink.

The Doc also seems to lump all runners into a single category when in reality there will people of all abilities participating in any given event, from the Elite to weekend warrior. Surely the fueling needs of the 4 hour plus “plodder” does not match those of an Elite marathoner who finishes in a little over 2 hours.

One reader also argued against the Doc’s information sources (Medical Human Physiology and Endocrnology textbooks on the stimulus and action of Insulin), that the “crashing” effect occurs when the body is at rest - an entirely different scenario than when you’re continuously active and placing the body under considerable stress as you do in a Marathon. Many more calories will be expended by your body and 100 cal of a gel will get sucked up pretty quickly as soon as it enters the bloodstream.

One point of unity in the discussion seems to be the acceptance that - in terms of fueling - what works differs from person to person and the importance of test your fueling strategy before a race.

The full thread can be followed here.

Technorati Tags: Fueling, Gels, Marathon, Performance