there are a myriad of possibilities Mac2.
One must adhere to the criteria of Dynamic correspondence in order to ensure that the transfer is direct; i.e. specific
RE Verkhoshansky
- accentuated regions of force production (where in the amplitude/range of motion are the greatest forces produced/incurred)
- amplitude and direction of movement (range of motion and direction in which resistance must be overcome)
- dynamics of effort (the nature of the motion specific to the exercise with and without consideration of the forces involved)
- rate and time of maximum force production (how fast and for how long is the maximum force generated)
- regime of muscular work (type of muscular activity ergo overcoming, yielding, sustaining, ballistic, etcetera)
As far as exercise classification goes, I subscribe to Bondarchuk:
- general preparatory
- specialized preparatory
- specialized developmental
- competition
This all reflects the discussion of specific training.
Alternatively, the general organism strength that is developed regardless of the exercise serves as a means of indirect transfer.
Prowler pushes, assuming the weight, speed of movement, and distance covered is appropriate relative to offensive line/back run block, running back going through the mesh, linebacker blitz, and defensive line bull rush is an effective specialized drill.
Tires may also be used effectively assuming enough criteria are satisfied.
thus, we see that in so many instances it is not the means itself that is in question; but rather the method of execution.
Per your post, the prowler and tire can just as easily be used with efficacy for a American footballer as they can be used disastrously.
Unfortunate for most American footballers is that, from what I’ve seen, the latter is the common result.