PUBLISHED 03/26/2007
The surest way to blow a 5-K is to start too fast. But just how fast is too fast?
Researchers from the University of New Hampshire examined the effect of different pacing strategies on 5-K performance. Their subjects were 11 female runners from the school's cross-country team, who trained an average of 35 miles per week and had 5-K PRs ranging from 18 to 21 minutes. After running two 5-K time trials to establish a baseline pace, the subjects then completed three more 5-Ks using decidedly different pacing strategies: The subjects ran the first mile of each race either equal to, three percent faster, or six percent faster than their established baseline pace per mile. After the first mile, the subjects could change their pace to finish as quickly as possible.
The results surprised everyone familiar with the go-out-easy approach. Eight of the 11 women ran their best 5-K times (averaging 20:39) when they ran the first mile six percent faster than their baseline pace. The other three subjects posted their best times (20:52) going out three percent faster than baseline pace. The even-paced runners produced the slowest times, averaging 21:11. The faster-starting women did slow down more during the race, but the even-paced runners simply couldn't make up the time lost in a slower start.
So how is it that these runners achieved their best times by logging their first mile a seemingly suicidal 26 seconds faster than their predicted 5-K pace? According to the study, at the end of the first mile, the even-paced runners were at only 78 percent of their VO2 max, an effort level more akin to a tempo run than a 5-K race--below their potential. The three-percent and six-percent faster starts put the subjects at 82 and 83 percent of VO2 max after the first mile, which is closer to the intensity you'd expect from an experienced runner racing the first mile of a 5-K.
So should we all go out as fast as possible in every race? Not exactly. Moderately trained runners may benefit from a faster start because they're probably not starting fast enough in the first place. The researchers suggest that their study findings are probably most applicable to competitive open and master's division runners, not elites who already know how best to push themselves right from the gun or beginners who totally lack a sense of pacing. And even competitive runners shouldn't try the go-out-fast strategy in longer races, when other variables become more important than first-mile pace--like, say, finishing another 25.2 miles.
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