Thursday, May 3, 2012

The Negative Split

The negative split is one of my favorite distance running techniques that is sure to help you cut seconds and minutes off of your race times.  A negative split is defined as running a later portion or a race at a faster pace than an earlier portion of the race.  In essence, you start out slow and speed up as you go, each split is successively less than the one before it (negative). But why would you want to do that and how will that make you faster? Let's start at the beginning.

When I began running, I, like many others, believed that you should start fast when you are fresh and slow down as you wear out and become tired.  Some call this 'banking time'. You are running faster than your goal at the beginning in an effort to bank enough time so that you can run slower later in the race.  There is a fundamental flaw to this line of thinking and it has to do with your physiology (fancy word for body science).  As you might already know our muscles get energy during running from glycogen (carbohydrates) and fat stores in your body.  Glycogen is limited in quantity, and even a well trained athlete will not last long running above 85% of their max heart rate. They will be running anaerobically and burning a great deal of glycogen and producing lactic acid in their muscles at a rate faster than it can be removed.  Lactic acid stops your muscles from converting fat into energy.  This will cause you to slow way down or even walk.  Your goal is to use your fat reserves, which are much greater in quantity and will keep you going longer.

The negative split running strategy coupled with the right aerobic training you can teach your body to use more fat and less glycogen which will allow you to run for much longer periods of time while burning fat and without running out of glycogen or generating large amounts of lactic acid.

So what can you do about it?  First focus your training to be aerobic, in the 60-75% of your maximum heart rate range for at least 30 minutes.  Yes that means running slower when training; it seems counter intuitive but it works.  And the next time you race, instead of going out at full speed and fading in the later miles, start out at a pace a few seconds per mile (10-15) slower than your goal pace for the first few miles, and slowly pick up the pace running each mile a few seconds faster than the last.  During the second half of the race you should be cruising at a bit faster than your goal pace and if everything goes correctly your second half will be faster than your first half and you will meet your goal.

Negative Split Works!

The first time I attempted to run a negative split it took almost 4 minutes off of my previous half marathon time where I went out at 6:59 at the start and slowed greatly at the end.  This time I started off at a 7:20 - 7:24 min/mile pace for the first 3 miles and had tons of energy during the second half of the race and passed several people.  I finished with an overall pace of about 7:09 min/mile.

First Half: 47:30  (7:15 pace)
Second Half: 46:03 (7:02 pace)

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