As of today, neither human surrogates such as crash test dummies and cadavers, nor mathematical models can take lower limb bracing into account. It is however reported that more than 50% of car drivers have time to anticipate an impending crash.

Based on an in-depth literature review, a mathematical representation of muscle tension was adapted from gait conditions to car crash conditions using available animal experiment results.

This mathematical representation uses 3 generic functions associated with 3 specific parameters to describe muscle mechanical responses.

Meanwhile, the human muscle/skeleton geometry of lower extremities was scaled to correspond to the thigh and leg lengths of the 50th percentile Hybrid III dummy model available in Pamsafe software.

For the model development, muscle paths were imposed using origins, insertions and a variable number of pulleys, in order to obtain proper muscle moment arms relative to the different joints whatever the position of the dummy.

A particular attention was paid to the knee extensors and to the patella.

The entire lower limb musculature was modeled using 18 equivalent muscles per limb, including both agonist and antagonist muscles responsible for the application of a load on a brake pedal or a foot-rest.

Dynamic cadaver experiments and volunteer tests were used both to determine the muscle activation coefficient set and to validate the contributions of passive and active muscle forces of the model.

Simulations show that muscle tension can significantly modify the dummy kinematics during a crash.