COMPARISON OF ANGLES AND THE CORRESPONDING MOMENTS IN KNEE AND HIP DURING RESTRICTED AND UNRESTRICTED SQUATS

The aim of this study is the comparison of angles and the corresponding moments in knee and hip during squatting. The five subjects performed restricted and unrestricted squats. The experimental set-up consisted of a motion capture system and two force plates. The loading conditions were 0, ¼ and ½ BW. The moments and the force were calculated using inverse dynamics. Overall, the maximal moments were observed in the knee during unrestricted squats and in the hip during restricted squats. Comparing the moments at a knee angle of 60º, the loading conditions have a larger influence than the type of execution. The moment in the knee is 10.4%, respectively 11.2% lower with ¼ and ½ body weight during restricted squats. In the hip, the moment is 15.5 %, respectively 14 % higher for the same conditions. The angle of the hip remains rather constant. This most likely implies a higher load to the lower back. Hence, the exercise instruction should be adapted to the aims and the training condition of the athlete

Veränderte Aktivierung der Vasti während dem Laufen als Merkmal des PFPS

Current literature discusses whether an earlier activation of the Vastus lateralis (VL) compared to the Vastus edialis obliquus (VMO) calculated relative to the heelstrike during running can be associated with the Patellofemoral Pain Syndrome (PFPS). The present study investigated the onset of the activity of both Vasti for a healthy control group (n = 12) and subjects suffering from PFPS (n = 14) during barefoot, shod running, and running with insoles (if available). Based on repeated measurements of the healthy subjects it was estimated that time differences between individual onsets of muscle activation and the later activation of the VMO related to the VL should be at least 25–30 ms to exclude to a high probability an interpretation biased by the given variance of the measurement performed with surface electrodes. The present results show that time differences of the onset of the activity of the Vasti between the two investigated groups were all between 5 and 10 ms on average, not significant, and not clearly distinguishable from the given variance of the measurement. Furthermore, using insoles did not result in a more simultaneous activation of the Vasti before heelstrike. Thus, an earlier activation of the VL compared to the VMO can not be considered as a single characteristic of patellofemoral pain. However, future work should investigate whether the muscular coordination of the Vasti in combination with the kinematics and kinetics of the lower extremity can biomechanically explain the occurrence of individual patellofemoral pain

Erfassen der Vor- und Rückfussbewegungen im Gehen und Laufen

The goal of the present work is to show how relative movements between (i) forefoot and rearfoot, and between (ii) rearfoot and lower leg can be measured and described during activities such as walking and running. For that purpose a 2-segment foot model is proposed (forefoot and rearfoot) composing of 9 markers to capture the foot movements. The results show considerable improvements of the 2-segment model compared to previous 1-segment models. This new model is particularly suited to demonstrate movement coupling between the rearfoot and the lower leg. Furthermore, the results with the new model show a remarkable plantarflexion between forefoot and rearfoot during take-off in walking and running. This movement can be considered as a deformation which reduces the leverage in comparison to an ideally rigid foot. This work constitutes a basis for improved three-dimensional description of the kinematics of the lower extremities during walking and running

Day-to-Day consistency of lower extremity kinematics during walking and running

Before conclusions can be drawn with respect to the quality of adaptations in human gait, the day-to-day consistency of the variables of interest must be known. The present study estimated the day-to-day consistency of kinematic variables collected during barefoot walking and running. Sixteen healthy subjects performed two gait analysis sessions based on skin markers. Test sessions were at least 1 week apart. In total, 48 ranges of motion were monitored for the hip, knee, ankle, and midfoot joint. Based on differences between the repeated gait analysis sessions, the day-to-day consistency was estimated. It was found that the day-to-day consistency was of the magnitude of 3 to 4 degrees for almost all ranges of motion independently of the test condition, the investigated joints, or the cardinal body plane. It was concluded that future studies on effects of interventions or on the characterization of pathological versus normative gait should consider the provided values of day-to-day consistency to improve their interpretation and conclusions