I notice that most elite level sprinters take about 44-46 strides (male) and 46-47 (females). this is a very vague question with thousands of variables. But lets say you have a HS girls who sprints about 12.4 fat. What would the reduction of one stride possibly yield in regards to time? I will answer what I can but I believe the question can be adequately addressed in general terms without adding too many specifics.
Are you assuming that only her stride length would change and that her stride frequency would remain the same? If so, it’s relatively easy to calculate.
Best,
Christopher
I’m going to go out on a limb and say that a 12.4 girl is about 50 steps. If we assume the stride lengthens for good reasons (so her frequency doesn’t change), that’s good for a 2% savings, so about a quarter of a second.
Good questions. She has a good stride rate already and I wouldnt want to slow that. I have ideas on how to maintain that but any particular concepts and ideas you have on making significant strength gains, monitoring effectiveness of ground contact and the ancilliaries of this function, and hip strength would be appreciated.
Thanks by the way for both of your responses. It answered my question
A small word of caution, if the goal is to increase your runner’s strength and ability to apply force into the ground, thereby reducing the number of necessary strides for her to naturally cover 100m and try and calculate the improvement of her time, then so be it, that would seem to me to be a reasonable approach. If however, it’s simply a question of trying to increase the amplitude of her stride to eliminate one step across 100m, then I’d suggest maybe not doing that and concentrate on increasing her strength levels and her ability to apply force, then see where you stand on the number of strides over X distance.
As for the math, 12.4 FAT divided by # of strides over 100m gives you the time per stride. Once you have that, just reduce the # of strides by 1 and reverse the calculation. Time per stride multiplied by the desired number of strides = new FAT. That assumes (naively maybe?) that all other things remain equal.
So to use the numbers listed…
12.4 FAT / 50 steps = 0.24s which is the average time per stride over 100m.
reverse the math to get the new time
.24s * 49 steps = new (very guesstimated FAT) of 11.76
That’s a substantial reduction in time across 100m and is a good indicator of why taking one less step over 100m is such a difficult proposition. The amount of strength and efficiency increases necessary to make even a seemingly small reduction in steps is actually quite a large jump and should be looked at holistically I feel, and not in isolation, as there are a large number of factors in play that will influence the how and why of the results.
Janic you rounded 0.248/stride to 0.24 before multiplying by 49. Without the rounding, you get 12.15 (or a quarter of a second savings).
Which is pretty much your 2% hey? 
You’re absolutely correct though.
Man that is substantial. Ok important safety tip, don’t forget decimal places when doing math relating to athletic performance metrics!
The longer the stride length the faster the footfall will be, gravity says Usain bolt will stay in the air the same time as everyone else regardless of the stride length.
Do you take into account acceleration, shorter steps at the start?
It’s an estimate in answer to a thought experiment.
Best,
Christopher
Would increasing the length of the stride in the acceleration stage have a greater affect on the time than the maintenance stage.
This is a very difficult question to answer with any degree of reliability for the “average athlete.” For the beginner, they very often chop their strides short in the first 10 metres because it “feels faster” to take a million short steps than fewer long ones. ESTI has found that by getting novice athletes to take bigger steps within the first 10 metres their 10m time would be the same, but their 20m time would drop by at least a tenth. I have also found this to be true.
I believe when Ku2u#1 was working with one of his football athletes, a similar cue resulted in a similar drop in time. Basically, getting them to fully extend in the initial stage (with for example, the 8th step landing further than it did from the start line than when the athlete was chopping their stride) would result in them taking possibly one less stride (more likely 1/2 of a stride less) in a full race.
Of course, if you overdo it, put a bunch of sticks down and start screwing with their max velocity stride length, I think you’re going to do way more harm than good. I know people here have said Pierre Carraz works on stride length with Christophe Lemaitre, but I’d like to see what he’s doing in the context of the overall program. He has done a very nice job of progressing Lemaitre.
1 minute of video is pretty much worthless when trying to determine the overall picture, but from these videos there sure are a lot of cones on the track:
http://www.youtube.com/watch?v=17eTG3tGclQ
And cones on a curve!
http://www.youtube.com/watch?v=qIZa-cM7II8
I’d love to hear Carraz talk in depth about his methods.
Only time I’ve seen sticks used was in warm-ups to work on not overstriding and stepping down/not flying out the back
If you use a spacing of 1.4m to marking/stick for 3 spacings and really ‘attack’(accel)
to reach/extend for each spacing, once you come out of the third spacing and begin letting your natural flow and frequency of your ‘personal limb ratio makeup’ come into play by relaxing, its pretty much a given that you’ll get to 10 m mark in 8 strides…i too used this for myself to achieve 10m, 20m, 30m personal bests…at first i felt like it was too long and that i was overstriding, but i
reassured myself it wasnt overstriding since i was maintaining 4 strides a second off the start, flowing into 4.5 strides a second starting at around steps 7-8.
In the video below d.miller has lashawn merritt establishing stride length and speed/rhythmn coming out of the first 10m…however, given his elite status, he has him getting to 10m in approximately 6.8 steps(right on par with longest 100m elite striders-bolt, powell, lemaitre, gatlin)
www.youtube.com/watch?v=XOWCZEs7__c
The more i analyze videos of 100m the more i realize its pretty easy for elite male sprinters to hit 10m in 7 steps(give or take so much centimeters)…alot of the decathletes do it…
Decathletes 100m- www.youtube.com/watch?v=5L2eC2Sofhk
Heat 1- 10.91…7 strides at 10m
Heat 2- 10.89…7 strides at 10m
Heat 3- eaton 10.3x, hardee, the canadian…all 7 strides at 10m
Heat 4- 10.71…about 7.3 strides at 10m
Eaton training vid: www.youtube.com/watch?v=JqoqleB7Giw
At 0:40 seconds eaton is getting to 10m in 6.5 steps, which is very similar to merritt(albeit with merritt on the bend
So how many strides do elite level female athletes average by 10 & 20 meters. Would the females benefit from the same adjustments in the beginning of the race?
I read an article recently discussing the fact that 7.5 steps for the first 10m seemed to be the universal amount regardless of standard…
Shelly ann fraser pryce- 8 strides(foot contacts), 9 strides(knee raises) at 10m.
Florence griffith joyner- 8 strides(foot contacts), 9 strides(knee raises) at 10m
Carmelita jeter- 8 strides(foot contacts), 9 strides(knee raises) at 10m