Trunk positioning has been shown to be associated with knee joint loading during athletic tasks, especially changes of direction. The purpose of the present study was to test whether a full-body compression suit (FBCS) would improve trunk positioning and knee joint control during lateral movements. Twelve female athletes performed lateral reactive jumps (LRJ) and unanticipated cuttings with and without the customized FBCS, while 3D kinematics and kinetics were measured. FBCS did not influence trunk positioning during LRJ and led to increased trunk lateral lean during cuttings (P < .001). However, while wearing FBCS, knee joint abduction and internal rotation angles were reduced during LRJ (P < .001 and P = .013, respectively), whereas knee joint moments were comparable during cuttings. FBCS cannot support the trunk segment during unanticipated dynamic movements. But, increased trunk lateral lean during cutting maneuvers was not high enough to elicit increased knee joint moments. On the contrary, knee joint abduction and internal rotation were reduced during LRJ, speaking for a better knee joint alignment with FBCS. Athletes seeking to improve trunk positioning may not benefit from a FBCS.
Guillaume Mornieux, Elmar Weltin, Monika Pauls, Franz Rott and Albert Gollhofer
Jana Fleischmann, Guillaume Mornieux, Dominic Gehring and Albert Gollhofer
Sideward movements are associated with high incidences of lateral ankle sprains. Special shoe constructions might be able to reduce these injuries during lateral movements. The purpose of this study was to investigate whether medial compressible forefoot sole elements can reduce ankle inversion in a reactive lateral movement, and to evaluate those elements’ influence on neuromuscular and mechanical adjustments in lower extremities. Foot placement and frontal plane ankle joint kinematics and kinetics were analyzed by 3-dimensional motion analysis. Electromyographic data of triceps surae, peroneus longus, and tibialis anterior were collected. This modified shoe reduced ankle inversion in comparison with a shoe with a standard sole construction. No differences in ankle inversion moments were found. With the modified shoe, foot placement occurred more internally rotated, and muscle activity of the lateral shank muscles was reduced. Hence, lateral ankle joint stability during reactive sideward movements can be improved by these compressible elements, and therefore lower lateral shank muscle activity is required. As those elements limit inversion, the strategy to control inversion angles via a high external foot rotation does not need to be used.
Caroline Divert, Heiner Baur, Guillaume Mornieux, Frank Mayer and Alain Belli
When mechanical parameters of running are measured, runners have to be accustomed to testing conditions. Nevertheless, habituated runners could still show slight evolutions of their patterns at the beginning of each new running bout. This study investigated runners' stiffness adjustments during shoe and barefoot running and stiffness evolutions of shoes. Twenty-two runners performed two 4-minute bouts at 3.61 m·s–1 shod and barefoot after a 4-min warm-up period. Vertical and leg stiffness decreased during the shoe condition but remained stable in the barefoot condition, p < 0.001. Moreover, an impactor test showed that shoe stiffness increased significantly during the first 4 minutes, p < 0.001. Beyond the 4th minute, shoe properties remained stable. Even if runners were accustomed to the testing condition, as running pattern remained stable during barefoot running, they adjusted their leg and vertical stiffness during shoe running. Moreover, as measurements were taken after a 4-min warm-up period, it could be assumed that shoe properties were stable. Then the stiffness adjustment observed during shoe running might be due to further habituations of the runners to the shod condition. To conclude, it makes sense to run at least 4 minutes before taking measurements in order to avoid runners' stiffness alteration due to shoe property modifications. However, runners could still adapt to the shoe.