Spatial distribution of fiber types in skeletal muscle: test for a random distribution

A statistical test is introduced for the assessment of fiber type grouping based on the number of neighboring fibers of different histochemical type. It is conceptually simple and can be applied to regular and irregular fiber patterns alike. One important feature of this test is that it has more power than existing ones, which means that deviations from a normal situation can be detected in an earlier stage than with any other method. The dependency of the outcome of the test on type-specific size differences is rather small. Moreover, a method is given to correct for this bias. With the aid of the test it is shown that in normal muscle tissue of young persons a slight segregation of fiber type is a common situation.