To Earn a PR, Pace Yourself

Joe Friel, one of the most respected coaches in endurance sports, just blogged about why the negative split is so crucial for endurance athletes. Joe says that he recently read about pacing and running world records.

"[The research] indicates that nearly all of the record-breaking times in the last 40 years or so have been run with negative splits."

A negative split is when you do the second half of something faster than the first half. For example, I can confirm that I eat the second half of an ice cream cone much faster than the first, mostly to prevent it from dripping all over my hand, which I hate. If I were to begin eating an ice cream cone really quickly at first, my tongue would go numb, I wouldn't savor the flavor, and I'd likely get a painful ice cream headache.

It's the same in endurance sports. If I burst off the start line, I'll likely get very tired quickly and then I'd have depleted much of my body's limited carbohydrate fuel stores (because I usually race without access to ice cream), and I'd be unable to recover. I'd either shock my muscles and they'd turn to lead or I'd race for awhile and then bonk.

Instead, the goal is to set a controlled pace, let the body, the muscles, and the fuel systems to adjust to that pace, and then gradually build into a higher speed. It's this gradual build to a higher, sustainable speed that makes the second half take less time than the first. This negative split is key to racing well. And when you do it right, it feels fantastic! Instead of feeling fastest at the beginning of the race and fading, which is frustrating, I race faster and faster all the way to the finish.

Joe concludes that "The bottom line here is, once again, that if you want to run a fast race it appears to be beneficial if you start conservatively and pace yourself so that the second half is run slightly faster than the first half.".

For cyclists who have on-handlebar computers, estimating pace is easy. How does one estimate pace while running?

• Run on a track.
• Run on a path that has mile markers.
• Trace a route on mapmyrun.com and get familiar with landmarks that approximate distances.
• Use a "foot pod". Foot pods relay stride length to a recording device, usually a wristwatch, but they must be calibrated and can't adjust for changes in stride length without recalibration. Many runners' stride lengths will change throughout a season and throughout a run, so food pods don't strike me as reliable.
• If you have an iPod, get the Nike+ device (Nike site, Apple site). This $29 device, profiled in the July issue of WIRED magazine, straps to your shoe and your iPod and estimates and records your running speed and distance. Next time you sync your iPod, you can upload your running data to the Nike+ website for logging and analysis. The Nike+ uses an accelerometer to measure how long your foot is in contact with the ground, which exercise physiologists have found to be a 95% accurate measure of running speed.
• Use a GPS device, like certain smartphones or a Garmin Forerunner wristwatch. Polar and Timex have GPS products, too, but they look enormous compared to Garmin products. GPS products track your speed over various time periods, which can give you your current pace, average pace, and much more.
  

Some day, running without a GPS watch will be like driving without a speedometer. Sure, there are purist runners out there who won't run with even a wristwatch, but there are purists in any sport until they've all become convinced by their faster peers. I just got a Garmin Forerunner 405, and I'll review it later.

Until then, pace yourself. It's the time-proven way to set a personal record.