Thread by @dr_jump_uk

#ForceVectorTheory. A force is, by definition, a vector. The name of the theory is thus a tautology and should really just be “Force Theory”. I thus propose the new name #TheoryOfTheMagicalHorizontalForceMuscle which more accurately captures the fundamental idea behind the theory

Biomechanics 101 - understand the distinction between global (relative to the world) and local (relative to the athlete) frames of reference. When people refer to “horizontal” forces they generally mean in the global frame #TheoryOfTheMagicalHorizontalForceMuscle

When an athlete wants to apply more “horizontal” force, they will have more body lean. The athlete is more horizontal relative to the global frame. #TheoryOfTheMagicalHorizontalForceMuscle

The strategy for applying “horizontal” force is thus to change the orientation of the athlete relative to the global frame, not to change the orientation of the force relative to the athlete.

Put another way, if an athlete is stood upright and jumps upwards, the force is vertical relative to the athlete and vertical relative to the global frame. If the athlete jumps for distance they will lean their body forwards. In this case the force is still vertical relative to

the athlete, but the force has horizontal and vertical components relative to the global frame.

Our main strategy for increasing “horizontal” force is to change the angle of our body relative to the global frame, not to somehow project more force horizontally relative to our body’s local frame. #TheoryOfTheMagicalHorizontalForceMuscle

The classification of both hip thrust and long jumping (say) as horizontal activities is logically inconsistent.

For the hip thrust force is horizontal relative to the athlete but vertical relative to the global frame. For the long jump force is vertical relative to the athlete but horizontal (and vertical) relative to the global frame. #TheoryOfTheMagicalHorizontalForceMuscle

There is no need to appeal to the #TheoryOfTheMagicalHorizontalForceMuscle to explain why the hip thrust might improve the performance of some exercises more than others. Dynamic correspondence provides a framework whereby the mechanical similarity of movements can be compared.

DC is based on a considered analysis of similarities in how force is expressed in 2 movements. DC requires a recognition of global and local frames of reference.

Finally, I hate people talking about horizontal or vertical forces like they are different things. Yes, forces can be resolved into their horizontal and vertical components. However, this is a mathematical trick to make analysis easier.

A force is a vector (arrow): when there is more "horizontal" force the vector is more parallel to the ground. This helps us understand how athletes direct forces - the angle of the athlete's body will be similar to the angle of the force.

Talking about horizontal or vertical forces (or horizontal to vertical force ratios) just leads to the type of misunderstanding inherent in the #ForceVectorTheory