Experimental data set used in Baxter et al. 2020, MSSE 'data' contains motion capture data (collected using Motion Analysis Corp. with Cortex), post-processed motion capture data exported as C3D and ASCII files, and OpenSim analysis files. 'opensim' contains preprocessing MATLAB scripts and opensim specific MATLAB scripts to batch process experimental data 'analysis' contains MATLAB scripts used to analyze biomechanical data processed in opensim. 'Supplemental Digital Content 1.xlsm' is a macro'd spreadsheet to calculate Achilles tendon loading indices based on user defined weighting factors for tendon peak load, loading impulse, and loading rate Please cite Baxter JR, Corrigan P, Hullfish TJ, O’Rourke P, Silbernagel KG. Exercise Progression to Incrementally Load the Achilles Tendon. Medicine & Science in Sports & Exercise. doi: 10.1249/MSS.0000000000002459