This is a video series on top speed. The videos cover physics, biomechanics, sprinting technique, and training strategies. The first video covers the physics of top speed and the primary factor that determines how fast someone can sprint.
Here is some supporting evidence for the first video. The graph below shows a model of vertical ground reaction force when the same athlete runs at different speeds. It shows how faster speeds require greater vertical force, which allows the small vertical jump on each foot contact to occur in a shorter time. The graph is from this study.
The next two videos discuss sprint mechanics and the interaction between force and mechanics. The key thing to understand is that mechanics rely on force production; the two cannot be separated. Some fundamentals such as posture and arm action can be changed in the short term and may produce immediate improvements in speed. But front side and back side mechanics are dependent on force. Greater force produces greater speed and more front side dominance, not the other way around. Note: In the videos I talk about "ideal mechanics." What I describe is a theoretically ideal technical model. In actuality no one actually follows that model perfectly, and it is physically impossible in some ways.
Next we cover some information that is important for interpreting much of the sprinting research. Understanding the concepts of force and impulse as well as the physics of acceleration is necessary to make sense of all the data from the various studies.
Speed Science 6 applies the understanding of impulse to the stride rate vs stride length discussion. This reveals the futility of intentionally trying to sprint with really long or really quick strides and brings us back to the fact that force production must be improved in order to increase speed.
Lastly, Speed Science 7 covers how to improve force production for sprinting by developing strength and explosiveness and managing the balance between the two. For more info read Long Term Athletic Development.