Tuesday, May 15, 2007

Run Faster, and Smarter

Controlling your Lactic Threshold, is one of the most important pieces of knowledge that you can learn.

"What is Lactic Acid and Where Does it Come From?

The carbohydrates you consume consist of several different sugar molecules; sucrose, fructose, glucose to name a few. However, by the time the liver does it's job, all of these sugars are converted to glucose which can be taken up by all cells. Muscle fibers take up glucose and either use it immediately, or store it in the form of long glucose chains (polymers) called glycogen. During exercise, glycogen is broken back down down to glucose which then goes through a sequence of enzymatic reactions that do not require oxygen to proceed. All of these reactions occur out in the cell fluid, or cytosol. They proceed very rapidly and yield some energy for muscle work in the process. This glycogen/glucose breakdown pathway is called the anaerobic (no oxygen) glycolysis (glucose breakdown) pathway. Every single glucose molecule must go through this sequence of reactions for useful energy to be withdrawn and converted to ATP, the energy molecule that fuels muscle contraction, and all other cellular energy dependant functions.

Factors that Influence the Rate of Lactate Accumulation in the body

Absolute Exercise Intensity- for reasons mentioned above.
Training Status of Active Muscles- Higher mitochondrial volume improves capacity for oxidative metabolism at high glyolytic flux rates. Additionally, improved fatty acid oxidation capacity results in decreased glucose utilization at submaximal exercise intensities. Fat metabolism proceeds via a different pathway than glucose, and lactic acid is not produced. High capillary density improves both oxygen delivery to the mitochondria and washout of waste products from the active muscles.
Fiber Type Composition- Slow twitch fibers produce less lactate at a given workload than fast twitch fibers, independent of training status.
Distribution of Workload - A large muscle mass working at a moderate intensity will develop less lactate thanhttp://www.blogger.com/img/gl.link.gif a small muscle mass working at a high intensity. For example, the rower must learn to effectively distribute force development among the muscles of the legs back and arms, rather than focusing all of the load on the legs, or the upper body.
Rate of Blood Lactate Clearance- With training, blood flow to organs such as the liver and kidneys decreases less at any given exercise workload, due to decreased sympathetic stimulation. This results in increaed lactate removal from the circulatory system by these organs."
Special Thanks to Stephen Seiler for explaining Lactic Threshold. Check out his full explanation @ The Lactate Threshold