The imposing mass of the trunk in relation to the whole body has an important impact on human motion. The objective of this study is to determine the influence of trunk's natural inclination - forward (FW) or backward (BW) with respect to the vertical - on body kinematics and stance limb kinetics during gait initiation. Twenty-five healthy males were divided based on their natural trunk inclination (FW or BW) during gait initiation. Instantaneous speed was calculated at the center of mass at the first heel strike. The antero-posterior impulse was calculated by integrating the antero-posterior ground reaction force in time. Ankle, knee, hip and thoraco-lumbar (L5) moments were calculated using inverse dynamics and only peaks of the joint moments were analyzed. Among all the investigated parameters, only joint moments present significant differences between the two groups. The knee extensor moment is 1.4 times higher (P<0.001) for the BW group, before the heel contact. At the hip, although the BW group displays a flexor moment 2.4 times higher (P<0.001) before the swing limb's heel-off, the FW group displays an extensor moment 3.1 times higher (P<0.01) during the swing phase. The three L5 extensor peaks after the toe-off are respectively 1.7 (P<0.001), 1.4 (P<0.001) and 1.7 (P<0.01) times higher for the FW group. The main results support the idea that the patterns described during steady-state gait are already observable during gait initiation. This study also provides reference data to further investigate stance limb kinetics in specific or pathologic populations during gait initiation. It will be of particular interest for elderly people, knowing that this population displays atypical trunk postures and present a high risk of falling during this forward stepping.

Teaching hypothetico-deductive clinical reasoning (CR) should be an essential part of the physiotherapy education system, but currently there are very few learning tools for teachers in the musculoskeletal discipline. The aim of this article was to describe and present the rules of a new game-based and structured didactic tool that can be used by teachers for ‘players’ (students and licensed clinicians) to learn systematic CR in musculoskeletal physiotherapy. Our tool is based on the ‘Happy Families’ card game, and we propose to use it as part of a classic musculoskeletal subjective examination-based hypothesis category framework and the International Classification of Functioning, Disability and Health model. It allows players to dynamically formulate hypotheses from clinical case studies. Each 'Family' of cards represents a hypothesis category. The game highlights the missing information and trains players to consider it in their CR. This game should efficiently structure all components of CR and is an interesting resource for all teachers. Its greatest strength is that it can be used with other category frameworks. Further studies are needed to assess the efficacy and efficiency of such a tool and to measure students’ actual progress in learning the CR.