Fiber-reinforced musculoskeletal soft tissues, such as the tendon, meniscus, and annulus fibrosus, are structurally and compositionally designed to transmit large mechanical forces and deformations over a lifespan. As a consequence, these tissues are highly prone to traumatic injury and degeneration. Moreover, no effective therapeutic options that restore the normal structure and function exist. Because the cells within these tissues ultimately govern the overall tissue health, it is imperative to investigate how the cells function within mechanically demanding environments in situ. However, currently there is a dearth of knowledge on how mechanical signals, such as strain, are transferred from tissue-level to the local matrix, cell, and subcellular structures in situ. Therefore, the objectives of this thesis were to investigate how applied mechanical strain is progressively transferred from the tissue to local matrix, cells, and nuclei in fiberreinforced tissues, and how this subsequently alters Ca²⁺ activities. The strain transfer behavior was found to be tissue-specific and heterogeneous. In addition, strain transfer from local matrix to cells and nuclei was dependent on fiber orientation and tissue type. In fibrocartilage tissues, such as the outer meniscus, proteoglycan-rich micro-domains (PG-rich µ-domains) emerged and grew in size with development and age. Interestingly, strain transfer to PG-rich µ-domains was significantly more attenuated than fibrous µdomains, where the cells within PG-rich µ-domains were subjected drastically strainshielded mechanical microenvironment. External strain applications recruited more cells to respond via Ca²⁺ oscillation both in situ and in vitro contexts. The PG cells were less responsive to the tissue-level mechanical perturbation than the fibrous cells in situ. Finally, the PG cells also exhibited highly distinctive baseline [Ca²⁺]i profile compared to the fibrous cells, suggesting PG-rich µ-domains may also impart other intrinsic regulatory factors for cell function. The findings of this thesis are significant at the basic science level because they greatly enhanced the current understanding of structure and function relationships of healthy load-bearing fiber-reinforced tissues across multiple length scales. The micro-mechanical and cellular benchmarks set in the current work are also particularly useful for future mechanobiology and tissue engineering investigations.