Originally, the force-vector theory may have stemmed from Verkhoshanky’s dynamic correspondence (read more about that HERE). Essentially, dynamic correspondence refers to increasing the working effect of the key movements of competition exercise through exercises that closely conform to the sporting movement (i.e. the training transfer effect). The working effect refers to increasing the maximal amount of force produced in a limited, or short time frame , and is otherwise known as the rate of force development.
There are two criterions of dynamic correspondence which give light to force-vector training. These are:
- Muscle groups of the training exercise must be the same as the competition exercise.
- Range of motion and the direction of movement of the training exercise must be the same as the competition exercise.
Force-vector training, therefore, allows coaches to identify training exercises that have greater specificity to the competition movements. For example, Contreras et al.  states that the since the hip thrust is performed in the anteroposterior force-vector (front to back), then it may have better transference to sports dependent upon horizontal force production (e.g. rugby, sprinting, football), as the horizontal force-vectors are anteroposterior when standing. In contrast, the squat may have a stronger transfer to the vertical jump due to its axial force-vector (top to bottom).
In two recent studies which examined the impact of force-vector training on athletic performance, both found greater improvements in the horizontal-orientated movements (sprinting and broad jumping) when training exercises were focussed on horizontal force-vectors [3, 4]. Likewise, greater improvements in the vertical-orientated movements (vertical jump) were observed when the training exercises were focussed on vertical force-vectors [3, 4].
Similarly, Contreras et al.  found a hip thrust group (horizontal-orientated exercise) made greater improvements in the standing broad jump, 10m and 20m sprint test (horizontal-orientated movements), compared to a front squat group (vertical-orientated exercise), who, in fact, showed greater improvements in vertical jump (vertical-orientated movements). Collectively, the findings from these studies support the force-vector theory.