This is the first series of troubleshooting to repair inefficient or physically dangerous fast bowling technique.
The bowling action is complex and prone to breaking down. While we want bowler's to bowl with natural actions, in many cases when we see a flaw we will be quick to try to iron out. This is because injury, and reduction in pace and performance is often associated with the flaw.
One of the most common of these flaws is; as a bowler comes out of her bound and into her back foot contact (BFC). We often see the back leg sweeping underneath the body and then land in a position towards the return crease. As the action is a chain of events only one thing can happen: A misalignment between BFC and front foot contact (FFC).
A common error is to work with the the bowler to concentrate on where their back foot lands at the crease. This is laborious and non-effective. Instead we find that the root cause of this deficiency comes further back in the bowling process; In the approach to the bound. If we deal with the root cause, the symptoms right themselves without direct interventions being applied to the "problem area".
We use video to confirm that most bowlers who sweep their back foot under themselves in the bound are people whose feet fall underneath their bodies as they run into bowl.
So do we need a high tech solution to this issue?
No. The technical toolkit for the remedy couldn't be easier or cheaper for that matter: A piece of string!
Lay the piece of string on the floor between the start of the run up and the point on the crease that you wish for the feet to align in the delivery stride.
Ask the bowler to run up placing their feet either side of the stride and not to step on the string or cross the string with their feet.
This will train the bowler to maintain an appropriate gap between the feet as they run in. This is really important as the action of sweeping the feet under the body in the approach is one of the main reasons why the back foot wants to come under the body in the bound.
Retrain the body in the approach and often, you will see the body continue towards its target in the bound and into the delivery stride. All this without having to explicitly coach or work on that phase of the bowling action.
So there you have it: A bit of knowledge, one long piece of string and all of a sudden you become a more effective fast bowling coach.