Determination of joint efforts in the human body during maximum ramp pushing efforts

Determining with accuracy, the internal efforts in the human body is a great challenge in Biomechanics, particularly in Physical Therapy and Ergonomics. In this context, the present study develops a human body model that permits a non-invasive determination of the joint efforts produced by a seated subject performing maximum ramp pushing efforts. The joint interactions during these experiments are provided by a dynamic inverse model of the human body, using a symbolically generated recursive Newton–Euler formalism. The theoretical investigation is presented in two steps, with increasing complexity and relevance: 1. Quasi-static analysis: this approximates internal joint efforts, using static equations at each sample, without taking the postural chain dynamic effects into account. 2. Dynamic analysis: this takes the dynamic effects into consideration and thus presents the advantage of a more relevant description of the motion as well as a more accurate determination of the forces and torques produced at each joint during the transient effort.The dynamic model confirms some previous studies of the effects of biomechanical factors on the performance of the task and is proposed as an accurate method for determining the joint efforts in dynamic contexts. Finally, this application is a preliminary benchmark case that will be extended to: • physical therapy, in order to analyse the joint and muscle efforts in various motion contexts, particularly for patients with fibromyalgia and patients with lumbar diseases; • accidentology, in order to analyse and simulate car occupant dynamics before a crash.