Why is my stride length so short and my acceleration so slow????

[quote]high school runner wrote: Also, I am extremely inflexible and I think I have poor hbiip mobility.

/quote]

stretch a whollllle lot

Your times are decent for hs 200 / 400. You attribute your weaknesses to short stride length and poor acceleration. However, don't confuse stride length as a cause of faster running, it is the result of faster running. Many coaches / trainers are still caught up in the 80's methods of speed training by trying to improve stride length and stride rate. Those are the results of faster running. We now know that speed is based on 3 components: the amount of specific force that can be generated at ground contact, the amount of time available to deliver that force, and how often a runner contacts the ground. Improve those functions and you will increase speed, stride length, and stride rate. Hip mobility is not directly related to any of the components of faster running (ie, muscular force at ground contact), so spending time with gadgets (elastic bands, parachutes, dragging weights / tires, etc) to "improve mobility" or improve acceleration is a waste of time. Think about it...when you add resistance, your ground contact is longer. That is the opposite of acceleration and speed. The fastest sprinters spend the least amount of time contacting the ground, but generate huge amounts of muscular force on contact. Think more of methods of training that will decrease ground contact-- plyos, short high quality sprints, and weight lifts that stimulate the fast twitch fibers (85% to 100% of 1rm). Good luck!