taken from Fitmetrix.io
Running has three components: Fall, Pose and Pull. No matter how you run and what your running technique is, you go through these three at every stride of yours.
Each part has its own perfect form or way of being done correctly/efficiently. Regarding pull, there are a few issues in the recreational running community and one of them is late pull.
How to spot it in the video?
Simply, right after the moving foot passes the standing knee the back foot should be leaving the ground. If a video is taken from someone’s running, assuming each frame is around 30ms, in the next frame after the one in which the moving foot surpasses the standing knee the back foot should have left the ground, or the runner is making late-pull mistake.
Ok, got it but what problem does late pull cause?
First of all, note that even a simple tiny mistake at running can harm you over time. Because it repeats so many times, it wears you off until it clinically becomes an injury. Regarding late pull, it meddles with the perfect timing you can have in your stride if you just let the front foot [passively] fall under your body. What happens is due to the change in the dynamics of running caused by late pull, the front foot lands ahead of the body adding unnecessary pressure to the landing knee.
Other issue is, in most cases, those who have late pull, push their back foot off the ground. Perhaps because they keep a portion of their body weight behind (the back leg of course), they need to exert an extra force to take their foot off the ground. This push would be unnecessary if they removed that back foot just in time (as aforementioned: after the moving foot passes the standing knee).
How to identify and fix it?
In the same way that high temperature (fever) shows infection, cadence at running indicates such mistakes. If your cadence is below 180 strides per minute you are pushing off the ground and most likely you have late pull too (otherwise why you keep that foot behind if you do not want an effective push forward?!).
The other more accurate way of identifying it is to have a video form analysis which I can do for free during special offer periods like now (Jan 2016). You can also ask someone to take a video of your running form and send it to me. That would be always free of charge. Best way is to flick me an email to get started: firstname.lastname@example.org .
To fix late pull, there is one way. You should gain your propulsive force from gravity. Falling forward must become the only source of generating force to move ahead. That is what I teach at Progressive Running.