To understand how these two sports might conflict, we need to
delve deeper into how muscles are controlled. Chad Waterbury had
this nice picture showing how a motor unit touches several
muscle fibres. I suggest those who don't know what motor units
are start reading up a little bit :-) Taking the biceps as an
example, this muscle has about 200 of these motor units to
stimulate all the muscle fibers. But you want to contract your
muscle, they don't all go fire at the same time. This is due to
the size principle, motor units of the smallest size will be
recruited first. For a more detailed explanation, I can
recommend Human Physiology: The Mechanism of Body Function As
this picture shows, your muscle fibers are divided into roughly
three groups. First the green ones are recruited: these are your
Type I fibers, meant for endurance. Then when you start to
recruit more motor units (by increasing the force of the
contraction), you recruit the yellow ones: these are your faster
Type II fibers, but as you can see the