Aggregate reproducibility package for fixed-kinematics virtual external-wrench sensitivity of modeled L5-S1 joint reaction in one squat trial

This record contains the author-created public reproducibility layer for a deterministic, single-trial OpenSim sensitivity study. The study quantified how a precisely defined bilateral virtual translation of the external hand wrench affected the modeled L5-S1 joint-reaction resultant when measured kinematics, ground reactions, hand-force vectors, and force application points were held fixed. The archive includes author-created analysis scripts, aggregate CSV and JSON results, numerical manifests, quality-control documentation, public figures, and unit tests. It contains no FATLS model, motion, external-load, or OpenSim-output time series; no raw participant data; and no private analysis exports. Figure 2 is a rendered plot of condition-difference time series, but the underlying FATLS-derived series are not distributed. The work is a bounded model-sensitivity analysis. It does not simulate a physical bar, a Zercher squat, direct disc-contact force, tissue stress, or injury risk.