An era is a commonly used word for a long period of time. When used in science, for example geology, an era denotes a clearly defined period of time of arbitrary but well-defined length, such as for example the Mesozoic Era from 252 Maâ66 Ma, delimited by a start event and an end event.
As you increase voltage to the muscle describe how it responds to the increased stimulus. As the voltage was increased from threshold to maximum voltage, there was a greater force in the muscle contraction. Once the maximum voltage (2500 mv) was reached, even if there was an increase in voltage, the force of the muscle contraction remained the same.
In this case the motor units are plotted in 10-g groups against the number of units in each group. As might be expected from the relatively large motor units found in the gastrocnemius muscle, the average tension per unit is higher (35 g per unit) with its largest units producing up to 120 g.