  Experimental observations suggest that the force output of the skeletal
muscle tissue can be correlated to the intra-muscular pressure generated by the
muscle belly. However, pressure often proves difficult to measure through
in-vivo tests. Simulations on the other hand, offer a tool to model muscle
contractions and analyze the relationship between muscle force generation and
deformations as well as pressure outputs, enabling us to gain insight into
correlations among experimentally measurable quantities such as principal and
volumetric strains, and the force output. In this work, a correlation study is
performed using Pearson's and Spearman's correlation coefficients on the force
output of the skeletal muscle, the principal and volumetric strains experienced
by the muscle and the pressure developed within the muscle belly as the muscle
tissue undergoes isometric contractions due to varying activation profiles. The
study reveals strong correlations between force output and the strains at all
locations of the belly, irrespective of the type of activation profile used.
This observation enables estimation on the contribution of various muscle
groups to the total force by the experimentally measurable principal and
volumetric strains in the muscle belly. It is also observed that pressure does
not correlate well with force output due to stress relaxation near the boundary
of muscle belly.
