What is a Lactate Threshold ?

I have been running for about eighteen months for a total of about 1300 miles.   I have also run twenty eight races.  After you accumulate this amount of mileage you begin to notice tendencies in your performances.

Why can't you simply run as fast as you can from the start of a five kilometer run and keep going until the finish ?  If you are sufficiently strong willed, can you mentally overcome the physical anguish to accomplish a start to finish sprint ?

The Jack Daniel's training book I purchased recently 'Daniels'  Running Formula'  mentions a lactate threshold.  This is defined as the point during exercise of increasing intensity at which blood lactate begins to accumulate above resting levels, where lactate clearance is no longer able to keep up with lactate production.

I ran a race in August of  last year, the Lebanon Area Fair 5K, where inexplicably I was so exhausted I had to stop not once, but twice before the race's finish.  After the race I was extremely dejected because I thought my conditioning had deteriorated to the extent I could not complete a 5K race without stopping.  I had successfully completed several 5K races prior to this race.

What I believe happened was I exceed my lactate threshold to a degree where I had to stop.  My body was not clearing the lactate as quickly as I was producing it.  For every run or race there is a pace for which you can maintain that speed for a prolonged period without a lactate buildup.  If you stay under this pace you can run relatively effortlessly. Exceed this pace and you will crash and burn.

This lactate buildup manifests itself in the form of a sensation that both your arms and legs suddenly collectively weigh fifty pounds more and every step is a labored one.  All gracefulness exits your stride. It's been my experience you have to slow down in hope you can reclaim enough energy to finish the race. I believe what's happening is you're giving your body a chance to help process the lactate buildup.

For each race the key is to find the maximum sustainable pace for the duration of the race.  The problem is their is no scientific, completely accurate method to determine this pace prior to a race.  I believe the more formal training regimen I have adopted (Daniels' Running Formula) for the Ukrops Monument Avenue 10K race will prove to be very beneficial in aligning my training (as prescribed by the book) with my racing goals.