The posture of elite athletes training to run invariably includes a forward body lean that helps produce faster times. The question with most sprinters is how far to take that lean, and what the posture should be for sprinters who want to maximize their speed. Leaning too far forward can force the sprinter to lose balance; not leaning far enough forward can prevent him or her from reaching top speed.
When running with speed, athletes need to develop a good body lean to get the most out of themselves. Sprinters who don't run with a good forward body lean are going to lose momentum as they sprint, instead of gaining momentum. To build speed and maintain it throughout the race, try to maintain a 45-degree forward body lean throughout your sprint.
Invariably, a runner will run with even more extreme body lean as she approaches the finish line. The sprinter will angle her upper body to get to the finish line when taking her final strides. This can give her a bit of an edge at the finish, but only if she doesn't start the lean too soon. That's because even the most powerful sprinters won't be able to hold their balance when leaning over at an angle greater than 45 degrees. Athletes who try to go past the 45-degree mark when sprinting earlier in the race will lose their balance and won't be able to maintain their speed.
While training, sprinters will try to practice their technique with an upright posture. That's because it is easier to practice getting into full stride with a high knee lift when standing upright. However, during a race itself, the forward lean of the sprint will help the sprinter accelerate with more momentum and move faster.