Variable or accommodating resistance training machines
And assuming that maximal bar speed is attempted, this produces a different peak velocity for the same force when using each external load type.
At higher velocities, the rate of change of force is quite low and alters little with each incremental change in speed.
However, in practice, most strength coaches use other types of external load for training and testing, with the most common being constant loads (like free weights).
Other training and testing equipment can include variable resistance (like machines using cams) or constant resistance, pneumatic machines (including Keiser machines).
The traditional, hyperbolic force velocity relationship properly describes the behavior of single muscle fibers but also seems to hold true for single joint movements.
The force velocity relationship of both upper- and lower-body multi-joint (compound) movements is not hyperbolic, but is in fact linear.