Additional file 1: Placement of inertial measurement units on the subject

A total of 12 IMUs were placed on the subject's sternum, pelvis, upper arms, forearms, thighs, shanks and feet as shown in the figure.

Velcro straps were used to fix the IMUs on the distal and lateral sides of the thighs, shanks and upper arms, on the dorsal sides of the distal parts of the forearms and behind the pelvis between the posterior superior iliac spines. One IMU was placed on the subject's sternum using a hook-and-loop fastener fold that was built into the subject's shirt. The foot IMUs were taped on the superior side of the metatarsi using athletic tape. The IMU placements were chosen based on prior experience in minimizing soft tissue error and matching orientation changes in the IMU to the orientation changes of the underlying bone.
Unlike in marker-based inverse kinematics, scaling the bony segments of the musculoskeletal model to the subject's dimensions is unnecessary in IMU-based inverse kinematics when no further analysis is done, and thus we did not scale the bony segments.