Waspy,
The fact is that the inertia of a mass requires a force to change its velocity, so a force (like that exerted by the turbine blade on the air mass) is imparted on a mass and the reaction force is measured.
If a mass is left at constant velocity, it will not change velocity until an unbalancing force is applied (Dr. Newton, first law) thus the force is applied to change velocity. Force comes first, at least according to Newton.