Why does my sprinter run a different split on every rep of the same workout?
A spread of times across a set of reps is usually more useful than the fastest time in it, and logging the whole set is how you find out which.
A coach runs a sprinter through six reps of 60 metres at the same rest and the same effort, and six different times come back. None of them match, and it is tempting to call the odd one out a bad rep and move on. The pattern across all six is usually more useful than any single number in it.
Two different things look like the same problem
A split can change rep to rep for two reasons that feel identical from the sideline. One is real: the athlete is actually running slower because fatigue, focus or recovery is different from rep to rep. The other is not about the athlete at all. It is where the phone was set, how the finish line was drawn, or whether the athlete started a half step before the camera rolled. A one-tenth swing from setup noise looks exactly like a one-tenth swing from fatigue until you check the pattern across the set.
What usually drives the real swings
- Incomplete recovery, where the rest between reps is shorter than the work the body still has to do from the last one.
- A pacing choice, where the athlete runs the first rep hard to prove something and pays for it on the fourth.
- A changed start, where a false step or a different foot forward in the blocks changes the first ten metres before the sprint even begins.
- Surface and wind, if the reps are not all run in the same direction on the same stretch of track.
Logging the whole set, not the best rep
The Workout page on StatLap times reps with rest between them on the phone and sends the whole session to the athlete's training log, not just the one time somebody remembers. That matters here because a single good rep tells a coach nothing about whether a sprinter can repeat it. A log of six numbers in a row, kept over a season of workouts like this one, shows whether the spread between the fastest and slowest rep is shrinking. That spread, not the fastest time in the set, is usually the better measure of whether a sprinter is actually getting more consistent.
A phone timing a rep tells you the number, not the reason behind it. It cannot tell you whether a slow fourth rep was fatigue, a bad night's sleep, or a mental lapse. What it can do is hand you six real numbers instead of one remembered one, which is usually enough to start the right conversation with the athlete.
Time your next meet with the phones you already have
Timing, the Film Room and the speed gates are free forever, with no account. A Club plan, $71 a month, puts your meets on your own results page, and one plan covers every phone.
Related
Why don't my sprinter's practice times match their meet times?
Practice reps and meet races are started differently, timed differently and run under different pressure, so comparing them directly invents a slump that was never there.
Read →Why do your interval times never make it past practice?
A split shouted across the infield and scrawled on a clipboard is a time that exists for about a day, and the fix costs nothing.
Read →Can you time the splits between each hurdle, not just the whole race?
A finish time tells you the result. The splits between hurdles tell you where the race was actually won or lost.
Read →Try it: Sprint timer app: 40-yard dash and flying sprints with one phone