Hi, i´ve just finished my “Excel Software” about:
How to know the frequency and the lenght of strides to set the new PB.
It is a plan sheet with lot of formulas that helps to calculate how can you reduce your PB due Stride Lenght improve or Stride Frequency.
It´s a 869kb file ( .xls extension ).
I don´t know how can i post this file here…( i don´t have a site yet ).
But i can send you if you need.
All i can say is that my baby is very nice… 
Formula? Spread Sheet?? Give me a break.
The appropriate stride length and stride frequency is that which is natural for YOU only, based on good technique, relaxation, your build type, height, proportionate leg length, adequate strength, and flexibility.
Ok Charlie, i know what you mean
but i´m tell you that is just a way to look how you could reduce your times with just a proper train focused on “strides lenght” using the methods described by you in other threads.
Give me an available e-mail and i´ll send you the XLS file to your comments.
Sure. Send it to info@charliefrancis.com and I’ll have a look.
I am a sprint/hurdle coach that has worked with some stride length stuff in the past. I would be interested in seeing the program and more than glad to provide some feedback. Please send to cammiee2000@yahoo.com . 
Coachs, i know that each one of us have the appropriate stride length and stride frequency ( natural form ) but, every time i record my sprints i think the lenght strides are shorter than the optimum, its almost a funny way ( a mix between an elite sprinter and Forrest Gump style ) based on this, i would like to know if there´s a way to improve the lenght stride or it doesn´t matter ?
From my own experience (and the other athletes and coaches I see/and talk to training on the track) I would suggest: forget to worry about stride lenght, better don’t think about it at all for now.
When I started sprinting I thought the same: the 100 meters can be broken down to stride lenght x amount of strides. That might be mathematically correct, but thinking: if I can extend my strides by 1 inch and maintain stride frequency I’ll be faster might lead to suboptimal training like trying to practising a “technique of overstriding”.
Issues to focus on might be:
- flexibility (instead of focusing on a new PB in squats mainly make sure your range of motion improves and/or is sufficient - if you get stonger in sqatting, too, you did a lot right…)
- should lead to point two: relaxation at high speeds
- techique: concentrate on sprinting with your hips as high above the ground as possible (and as your strenght level allows)
- increase your strenght continuously
Sprinting is a complex thing and somehow every aspect depends on the other, too much to think about at 10, 11, 12 m/s…so sometimes you can only depend on a experienced coaches judgement and your improvement in times 
Maybe it does not sound satisfying, but fact is: if you run faster, your stride lenght will increase (if it’s too short now).
Remember Charlie giving Ben’s example - his times still dropped considerably, but it took him the same amount of steps to cover the 100 (his overall stride lenght was the same, although it changed within different sections of the 100m).
The only reliable factor about speed is minimal ground contact times - the things mentioned above should lead to that.
Hope it helps, but I guess some of the more experienced coaches can make it clearer.
Based on observations on sub11 female sprinters and their performances at Junior level, some improved in reducing stride length, some in increasing it. Every way is possible. But all improved significantly their contact time to stride length ratio, a good indicator of force efficiency. GCTime reduction alone isn’t enough for me, what do you think?
Sounds reasonable to me - but for better understanding: What could be the mistakes an athlete makes when GCT is reducing, but times are not? What is a possible scenario?
Common mistake would be not full action on the ground (noticable by too small knee angle at take-off or little foot extension. Merlene Ottey is the '90s was faster than in the '80s but had significantly longer GCT. There’s no rule here.
that’s very interesting! do you have any data on GCT compared to stride length of some elite male and/or female sprinters?
Thx - very interesting (especially with a prominent example like Ottey). A visible “too small knee angle at take-off or little foot extension” would also mean hip visibly closer to the ground, too, or am I wrong?
Sorry for bombarding you with questions.
Of course helps !! Tks a lot !! I´ll try relax while i´m running and work on this points. Tks Sly !!