Please take a look at the above image of a runner at the same phase of gait. This is an athlete that I've been working with for the past month. The image on the left is from day 1 and the image on the right was taken earlier today. In the past month he's gone from having a 5k pb of 21.02 to running a 5k in 19.05! This I feel is primarily due to improvements made in his technique. The 3 things that strike me here are:-
The chest is up and he's less hunched over in the right hand picture (as the red line shows). This allows for more hip extension meaning the glutes are able to fire more effectively at terminal stance. This also takes demand off of the lower back and by running more upright the pain in his lower back has actually diminished.
The head position is much better. As the yellow line shows on the left, his head is way out in front of his centre of mass, leading to an uneven weight distribution. On the right however, as the torso becomes more upright and the chest opens up, the head is getting closer to the centre of mass.
The heel lift. As the green line shows, he's raising his heel much more than a month ago, which allows more hamstring activation and therefore takes demand off of the hip flexors (for more information, see this past post.)
By Marc Brown