News
Weight Stack Numbering Logic
We are often asked why the weight plates on our pin loaded range of machines are numbered instead of indicating the weight in kilogram. The rationale for this is as follows:
On only 3 pin loaded machines, i.e. the Lat Pull Down, Seated Row & Tricep Pushdown, does the weight of the weight plate roughly equate to the actual load worked against. Even then, a variance exists due to friction caused by the guide rods, pulleys, cables and bearings.
On all other machines the load varies considerably from the weight of the plates due to lever arms, variable resistance cams and complex pulley arrangements.
In the case of machines with complex pulley arrangements (e.g. Cable Crossover), the load lifted is half the weight of the plates, but this is then dramatically altered by the angle of pull between the cable and the working limb.
On all machines with lifting arms (e.g. Chest Press) or variable resistance cams (e.g. Leg Extension), the weight lifted is not only modified by the mechanical advantage of the cam or the lifting arm, but the load also changes through the movement. The load not only simply increases or decreases, but normally does both (e.g. the load may increase initially and then decrease again).
Furthermore, on compound movements, the extent of the change is determined by the range of movement, which in turn is influenced by multiple factors, including user size, degree of pre-stretch employed, finish position, user flexibility, grip used, speed of movement and technique.
In other words, it is only theoretically possible to correctly calculate the load lifted on a given machine, for a given person, for a given technique, through a given range of movement, at a given speed.
