Effects of load distribution of upper and lower Limbs on the "Set" position posture in the sprint start

Engineering of Sport 15 - Proceedings from the 15th International Conference on the Engineering of Sport (ISEA 2024)

In short-distance races, the total race time is directly influenced by the “set” position posture. Related work on “set” position posture has shown that faster athletes exhibit two key characteristics in the placement of their center of body mass (CM): the height of CM (YCM) is closer to the ground and the horizontal projection of CM (XCM) is as forward as possible. Most prior works have focused on the lower limbs and relatively few have investigated the upper limbs, especially in terms of the ground reaction force related to the load applied to the upper limbs. We hypothesize that shifting the load distribution between the upper and lower limbs to the upper limb side during the “set” position would make the YCM lower and the XCM more forward (i.e., closer to the characteristics of faster athletes). In this study, we investigate the effects of greater load distribution to the upper limb side during the “set” position on the CM and muscle activities. Our results showed that increased upper limb loading could be one new strategy for achieving the characteristics of faster athletes and indicated that a need for in-depth exploration of additional postural and muscular characteristics that lead to an efficient start in front load conditions.