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ABSTRACT: 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 if medial compressible forefoot sole elements can reduce ankle inversion in a reactive lateral movement, and to evaluate those elements' influence on lower extremity's neuromuscular and mechanical adjustments. Foot placement and frontal plane ankle joint kinematics and kinetics were analyzed by 3-D motion analysis. Electromyographic data of mm. triceps surae, peroneus longus, and tibialis anterior were collected. This modified shoe reduced ankle inversion in comparison to 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 utilized.
Journal of applied biomechanics 08/2012; · 0.76 Impact Factor
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ABSTRACT: Load-dependant adjustments in lateral jumps are thought to rely on foot placement and on upper leg's kinematic and neuromuscular adaptations. The aim of this study was to elucidate task-specific adjustments during the initial impact phase under varying stretch-loads by the comparison of lateral jumps and lateral landings. Ten subjects performed lateral jumps and landings from four distances. Electromyographic (EMG) data of five lower extremity muscles were measured, whilst lower extremity kinematics and kinetics were analysed by 3D motion analysis. Lateral jumps were characterized by increased impact forces, higher lower extremity joint moments with exception of the initial knee abduction moment, greater sagittal knee and hip joint displacements, and a further exorotated foot placement. In lateral landings frontal ankle and hip joint displacements were greater. Thigh muscle and m. tibialis anterior (TA) pre-activity as well as initial post-impact EMG were higher in lateral jumps than in lateral landings, whilst during the reflex-induced phase thigh and shank muscle EMG, except for TA, were enhanced in lateral jumps. From these findings it can be concluded that task specificity in lateral jumps in contrast to lateral landings impedes a stretch-load adequate modulation of initial impact forces which particularly affects ankle joint loading. Foot placement seems to play a decisive role for limiting lateral ankle and medial knee joint loading. Therefore, in sports containing high-impact frontal plane movements a special emphasis in training routines should be paid to foot placement strategy in those movements. Such training interventions might contribute to injury prevention in lateral movements.
Arbeitsphysiologie 02/2011; 111(9):2327-37. · 2.15 Impact Factor
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Arbeitsphysiologie 07/2010; · 2.15 Impact Factor
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ABSTRACT: The classical stretch shortening cycle (SSC) describes sagittal joint flexion-extensions in motions like running or hopping. However, lateral movements are integral components of team sports and are associated with frontal plane joint displacements. The purpose of this study is to identify neuromuscular and kinematical mechanisms determining motor control and performance of reactive laterally conducted SSCs. Lateral jumps were performed from four distances in order to investigate the influence of lateral stretch loads on the lower extremity. Electromyographic (EMG) data of nine lower extremity muscles were collected. Foot, ankle, knee, and hip kinematics were recorded by 3-D motion analysis. High stretch loads were characterized by a greater foot exorotation during the initial phase of contact. In the sagittal plane knee and hip joint, displacements increased, whereas in the frontal plane only the hip joint displacement was significantly raised. In particular, frontal peak joint moments increased with stretch load. Thigh muscles' mean pre-activity amplitude was enhanced. It was possible to detect stretch reflexes in the thigh muscles, whereas in particular the short-latency reflex (SLR) was stretch load-dependently modulated. The results of the present study suggest that the foot exorotation seems to play a decisive role in the movement control of lateral jumps. The association between exorotation and increased sagittal joint displacements may be seen as a compensation strategy to shift load from the frontal to the sagittal plane. Lateral load compensation seems to strongly depend on upper leg's kinematic and neuromuscular adjustments, rather than on the ankle joint complex.
Arbeitsphysiologie 05/2010; 110(1):177-87. · 2.15 Impact Factor
