Strength Functions describe the power from the thighs and shins that is available to power the pedals.  Strength functions are explained and examples of their use are given.

Powering the Pedals, Powering the Model
A torque is a tendency to rotate.  Muscles rotate the thighs about the hip and rotate the shin about the knee.  The strength and speed of the motions of the thighs and shins  power the pedals.  Thighs and shins can move in two directions.  Muscles that bend the thigh and shin relative to the torso are called thigh and shin flexors.  Muscles that move the thighs and shins in the opposite direction are called thigh and shin extensors. The torque produced by the thigh or shin can be different at each point in the range of motion and depends on the speed of motion.  The torque at each point is described by a function here called a strength function.  The strength and direction of the thigh and shin extensors are represented by green arcs on the thigh and shin in Figure 1.   (Some readers may think of these strength functions as strength curves or moment functions or couples.) 

Strength functions are created from curves fitted to the list of Fit Points given to the model. The dots on the plot below are Fit Points given to the Model for this example. The numbers on the horizontal axis refer to the range of motion of the Shin (top plot, Theta5) and Thigh (bottom plot, Theta2). See Figure 1 for nomenclature.

Input 
Thigh and Shin Extensor and Flexor Fit Points are lists of points that the Pedaling Model uses to define the Thigh and Shin Extensor and Flexor strength functions. Such lists should have values spaced evenly over a range of motion and are in units of N m. 

Fit Points Example: 

          {0., 88., 200., 232., 240., 232., 200., 88., 0.} 

• The list begins and ends with "curly braces, {}"
• Each value must be separated by a comma.
• The model requires at least four points.
• Values can be zero; a "zero valued moment function." is {0,0,0,0}. 
  A number in front of the list has the effect of multiplying all the values in the list by this number, i.e., 2 {0., 88., 200., 232., 240., 232., 200., 88., 0.} would give the same result as {0.,166.,400.,464.,480.,464.,400.,164.,0.}.