# Acceleration curves

I know it’s accepted that as performance goes up, the distance it takes to reach top end speed gets longer. What are the main reasons for this? In other words, why does an 11.00 second 100 meter guy hit top speed sooner than a 9.95 guy? I know that the 9.95 guy will be faster to all points along the way, but why the difference where top end speed occurs?

I would maybe think in terms of absolute time and not distance. If athlete A and B reach top speed at the same time 6s in a 100m, but athlete A reaches 10m/s and athlete B reaches 11.5m/s, athlete B will be further ahead than athlete A.

I think Syrus is right. If you actually look at the curves, whether it be velocity vs distance or velocity vs time, the faster runner is usually (not always) going faster at any point (distance or time).The faster runners curve usually (not always) has a steeper acceleration curve AND the curve extends higher (faster). He simply continues accelerating and going ever faster while the slower runner plateus.

I was looking at some splits from the 2008 US Olympic Trials Womens’ 100 meters and was surprised to see the fastest segments occurring in the 50-70 meter zone. The final times ranged from 10.85-11.22 which is more than one second slower than the guys yet the fastest splits were in a similar zone. Just trying to understand why.

Top speed is usually achieved between 6-8s with varying degrees of abilities to maintain it. Speed still follows a parabolic curve. Thus typically you will see top speeds achieved between 50-70m for most trained individuals at the elite level. In recent times we have seen some of these segments stretch out to 8s. However, you need to also remember that those splits you are talking about are averages for 10m. The actual point at where the max speed and duration of it is unknown unless you have access to laser recordings. So when you get a split at 50m, 60m, 70m and the fastest split is 70m it could be the 60 or 50m where peak speed is achieved especially if the splits are close say 0.86, 0.85, 0.85. As there are errors with measurements you can’t say with 100% confidence where the peak speed was achieved as its an average measurement over a 10m segment.

Are you saying that it takes the same 6-8 seconds for the 13.00, 12.00, 11.00, and 10.00 performers to reach top speed? What about the thought that with women there is a greater contribution from speed endurance? I just assumed that as 100 meter time goes up, speed endurance becomes more of a factor?

This will be the case as speed follows a curve with variations in the steepness to the left upwards or to the right based on individual qualities. That is it builds up to a peak and degrades at varying differences. For the trained and experienced elite athletes that is trained 100m athletes all tend to fall in a given period the 40-50m (some females) 50-60m or 60-70m and recently even in the 70-80m splits (some males) with most between 50-70m (males and females being in this phase). Thus around that Now keep in mind the actual point could be at the 49m point or 71m point unless you have a laser on the individual you won’t be able to accurate determine the precise location. So what this means is you could have two elite females sprinters whom run 11.2s where one hits peak speed at 51m and the other 64m with the difference accounting for time being the variation in acceleration distance and speed maintenance. On the other hand as splits times are on average i.e. 0.92s for 50-60m and 0.92s for 50-60m it may appear as they are the same time but the measure isn’t sensitive to be precise enough. When you are talking about 12, 13, 14s sprinters they will obviously hit top speed much early because as mentioned the max speed is achieved earlier. Thus much of there time is spent slowing down and thus in a speed endurance phase. When you are looking at those USA splits the max speed could be being recorded anywhere over 20m even though it falls in the 50-60 and 60-70m split as this is an average for the ten m segment. With respect to men and women there are are men who run 10.3s and hit there peak between the 40-50m segment (lets say around 47m) and those that run 10.3s and hit there peak in the 50-60m segment (lets say 60m) thus you can see the variation in the required speed endurance qualities do so. Thus a 11.2s female may hit top speed in the same segment i…e 50-60m however it in reality could be 10m difference i…e the female could be hitting it at 50m and the male at 60m however the fastest split is recorded as 50-60m zone but its actually occurs at 50.1m for the female and 60m for the male. Hope that clears things up but if you think of it in this way you are born capable of say 8s of max energy but untrained you hit your top speed at say 5s over the years you train up to be able to use 7s of this max energy source. What this means is you run faster for longer. However, the final finishing time is dependant on having speed endurance in place. this is why you can have two males run 6.50s to 60m and one finishes in 9.95s and the other in 10.20s as there ability to maintain speed varies significantly. Just to confuse you a little more you could also have two sprinters who run 10.20s with one running 6.50s and the other 6.65s to 60m. Cheers