Strain rate tensor mapping can be conveniently computed from velocity encoded phase contrast imaging. It provides a tool to explore local tissue deformations including the magnitude and directions of the principal axes of deformations. The study of the variation of strain rate indices with force output (% Maximum Voluntary Contraction (MVC) can provide additional information similar to stress-strain relationships measured at the whole muscle level. Here, we present the methodological developments to extract 2D Strain rate indices as a function of %MVC in 6 normal young (3) and senior (3) subjects. An approximately linear variation of SR indices with %MVC force was seen in the range of 20-50% MVC in young and senior subjects.