In the fourth installment on this blog series on running a fast forty yard dash, I’m going to address what you should do to start your run. Recent research (1) on the fastest runners in the world has indicated that the first two steps of an acceleration are distinctly different from the acceleration or ‘drive phase’ that occurs in the following steps. In the initial two steps, the athlete achieves their highest change in velocity over the course of the run and their stride characteristics are markedly different than the subsequent steps.
There are several goals that must be met over the first two steps of a forty yard dash to run as fast as possible. Among the more important goals are the following:
- Move center of mass ahead of the base of support as far as possible to create an efficient position to generate horizontal force application.
- Develop momentum in the most efficient means possible by taking advantage of the relationship between impulse and momentum.
- Position the athlete such that they can continue to accelerate efficiently beyond the first two steps.
- As a nice coincidence the techniques associated with each of these goals will help you achieve the others. Let’s take a look at how we can meet these goals and start off our forty yard dash with explosion.
As mentioned in the previous post in this blog series, the athlete’s center of mass should be well ahead of their base of support (their feet). This is a great position for generating horizontal force…it’s the same reason we lean in to a car or other heavy object when trying to push it forward. Such a position will also help to beneficially affect the athlete’s time that they’re able to push on the ground. When the heel recovery of the swing leg is kept low and the leg is fully extended at toe off, the time the athlete pushes back on the ground is optimal. The best way to develop momentum is via a high impulse. Impulse is the product of force and time. With this in mind, if we want to cause big changes in momentum and rapidly accelerate our body, the best way to do it is to apply huge forces over appropriately long periods of time. To do this the first couple steps should be characterized by big, complete pushes. Attempting to force an overly fast turnover during these initial steps will violate these principles and not adequately develop momentum or accelerate the athlete. It will also cause poor body positions which will later catch up with the athlete in the subsequent steps.
References
Mann, Ralph (2012). The Mechanics of Sprinting and Hurdling.