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Tuesday, June 21, 2005
Updated: July 22, 4:59 PM ET
Power up: The role of glycogen replacement

By Ben J. Character, DVM
Veterinarian
Special to ESPNOutdoors.com

Running Lab
As your dog runs for a retrieve, his muscles use glycogen as energy. By replacing that energy source soon after exercise, you can keep him performing at a high level for several days in a row.
The athletic retriever works hard. He runs the rivers, marshes, and potholes returning ducks, geese, or any other flying water bird that looks good on the table or the wall.

The best analogy for the retriever athlete is to that of a basketball player. From tip-off to the buzzer, the player is basically involved in a series of wind sprints. After a basket is made or missed the wind sprint cycle is repeated over again as they move from one end of the court to the other. These short bursts of activity are what compare to our retrievers.

The shot is made and the bird is down. The retriever is sent. He goes as hard and as fast as he can after the bird. Next he searches for the bird, locates it, and swims or runs to it. He then returns as quickly as possible, to do it all over again. If multiple birds are down this continues for several more cycles — go-find-return over and over again.

Understanding this give us important clues as to what is going on inside the retriever's muscles while he works. During the work of the go-find-return cycle retrievers utilize a specific energy production mechanism called the Glycogen-Lactic acid system.

This system utilizes the sugar (glycogen) stores found in the muscles and converts them into energy for use in short to medium duration activities. Glycogen is a short carbohydrate that when needed for work, is split into glucose. The glucose is then sent through an enzyme cascade that produces energy. It can work very quickly because it only requires a few enzymes and no oxygen to produce energy (known as ATP). The speed of energy production matches the short massive bursts of muscle use that occurs during sprints and retrieves.

Just as basketball has its time-outs, a natural rest period exists between each cycle of go-find-return for retrievers as more birds are called or waited on to arrive. It is during this rest period, that the muscles are allowed to catch up and use newly available oxygen to prepare for the next work cycle. If these activates are repeated continuously without rest, glycogen stores are depleted to the point that a new energy system must be used. When this happens the retriever begins to utilize systems more like what a bird dog will employ. But the main energy production system used by the retriever remains the Glycogen-Lactic acid system.

Research has shown that under normal feeding conditions, once depleted, muscle glycogen stores require several days to be re-established. But while this is true when normal dog meals are fed under normal conditions (usually several hours after work), the conditions present directly after work are a different story.

Immediately after work, and for up to 20-30 minutes, muscle metabolism enters a period of rare metabolic activity. During this time if simple sugars are supplied, energy sources will race through normal metabolism, bypassing slow transport and enzyme systems, straight into the muscle cells where they are taken up and metabolized into glycogen for storage.

  About Ben Character
Dr. Character is a freelance writer and private veterinary practitioner concentrating on sporting dog issues.

He has practiced large and small animal medicine and surgery since graduating from Auburn University. Recently, he went on to complete post-doctoral studies at Mississippi State University.

Dr. Character is a certified PennHIP member and writes for magazines such as Retriever Journal and Pointing Dog Journal.

He is an avid outdoorsman who resides in Union, Alabama, south of Tuscaloosa, with his wife and two children.

When this process is taken advantage of, muscle glycogen stores can be replenished quickly. This prepares the retriever for work again much faster than normal feeding methods. The lack of available energy seems to be a vital component to a quick rebound. Just like a hot-rod with an empty nitrous tank, the retriever without muscle glycogen available will not have the boost of the dog with a full tank of glycogen.

It is very easy to supply these simple sugars that can be used by the post-workout muscle systems. The most effective solutions are those with the simplest form of carbohydrates (sugars), glucose. There are a couple of canine "sports drinks" available, such as the product Glycocharge, that utilize these simple sugars and seem to be very effective. An alternative is to simply make your own sugar solution. Though the structure of table sugar is not quite as "simple", a solution made of dissolved table sugar can give your retriever a significant boost. On the other hand, Gatorade and other "people" sports drinks should be avoided.

Next time you need to have your retriever at his best for several days in a row, consider trying this method. Now that you know what's going on inside those muscles you'll be better able to keep them working hard. If you'd like a simple recipe for making your own post-work energy drink for your dog visit my website at www.sportingdogclinic.com.