Strength training can improve muscle
strength. What would be the specific benefit from strengthening particular
muscle groups?
One may want to estimate benefit from changing the shape
or magnitude of a strength function (for example, pedaling by pushing sooner
and reaching maximum effort for a longer portion of a pedal stroke).
The Pedaling Modal may be able to help you decide if the training you are
contemplating is going to meet your expectations. The following examples
illustrate the concept.
"Quads" Only
Suppose we want to study the effect of pedaling
using different muscle groups. For example, suppose
that we wanted to study the effect of pedaling only with the
shin extensors, the "quads." The following table gives power
from pedaling with "quads" only:
Power From Base Case (Use all muscle groups) 
528.9 
watts 
Power From Test Case ("Quads" only) 
67.6 
watts 
Difference 
458.3 
watts 
% Difference 
87.1 
% 
This is a very large difference. (These values are hypothetical.
With more developed "quads" or less developed thigh extensors,
the results could be very different.) In the above
table, the base case was evaluated with default values for Thigh and Shin
Extensor and Flexor Fit Points. In the test case, Shin Extensor Fit Points
were at default value and Thigh Extensor and Flexor and Shin Flexor Fit
Points were set to {0,0,0,0}.
"Pushing" Only
We read anecdotal comments that a rider can only pedal by pushing on
the pedals. How does power from "pushing only" compare with pedaling
using all the muscles?
Power using all muscle groups 
525.9 
watts 
Power from Pushing Only 
440.1 
watts 
Difference 
85.8 
watts 
% Difference 
16.3 
% 
The relatively small difference would show that "pulling
up" is not nearly as important as "pushing down," but "pushing
only" neglects an important source of power. (These values are hypothetical.
your results could be very different.) In the above table, the base model
was evaluated with default values for Thigh and Shin Extensor and Flexor
Fit Points. In the "pushing only" case, Thigh and Shin Extensor
Fit Points were at their default values and Thigh and Shin Flexor Fit Points
were set to {0,0,0,0}.
Strength Training
So, you're going to work real hard in the gym this
winter, build up those quads, look like a real biker when you're done. What
results can you expect? The following table shows the before and after results
from changes to thigh and shin extensor and flexor strength functions.
For example, suppose a rider improves the strength of the
shin extensors (quads) by 50%. How much will this change a rider's theoretical
power output? This table shows the results of 50% stronger Quads:

Power 
Base Case 
525.9 
50% Stronger "Quads" 
545.0 
Difference 
19.1 
% 
3.6 
Same 50% increase but in the thigh extensors:

Power 
Base Case 
525.9 
50% Stronger Thigh Extensors 
706.0 
Difference 
180.1 
% 
34.2 
Results based on your data could be very different. 