China 
Africa 
Explore chapters and articles related to this topic
Lower extremity injuries
Published in Youlian Hong, Roger Bartlett, Routledge Handbook of Biomechanics and Human Movement Science, 2008
William C. Whiting, Ronald F. Zernicke
When the knee is fully extended the patella rides high on the femur. As the knee flexes, the patella slides in the intercondylar groove in a movement termed patellar tracking. Effective patellar tracking depends on structural congruence between the patella and femur, the net effect of muscle forces (i.e., vastus medialis, vastus lateralis, vastus intermedius, and rectus femoris) and other structural considerations (e.g., Q-angle). As the patella tracks, contact pressures develop between the patella and femur. These pressures, determined by the contact forces and areas, vary with knee flexion (Figure 27.3). As the knee flexes, PF joint contact area increases and the knee flexes from full-extension, with most of the increase happening in the first 45–60˚ of flexion (Salsich et al., 2003). In addition to increasing in size, the contact area migrates superiorly on the retropatellar surface as the patella slides deeper into the intercondylar groove (Figure 27.3).
Effects of low load exercise with and without blood-flow restriction on microvascular oxygenation, muscle excitability and perceived pain
Published in European Journal of Sport Science, 2023
Mikkel I. Kolind, Søren Gam, Jeppe G. Phillip, Fernando Pareja-Blanco, Henrik B. Olsen, Ying Gao, Karen Søgaard, Jakob L. Nielsen
Thus, altogether, it appears important to characterize the level of microvascular oxygenation, muscle excitability, and blood-pooling in response to partial LL-BFR and LL-FF exercise performed to task failure. However, only a few studies have combined measurements of microvascular oxygenation and muscle excitability, and only one of these studies appears to have used protocols performed to failure (Ilett et al., 2019; Kacin & Strazar, 2011). Furthermore, previous findings have observed differences in intermuscular knee extensor microvascular hypoxia during submaximal cycling exercise (Koga et al., 2011), yet the effect of LL-BFR exercise performed to task failure on microvascular tissue oxygenation and/or blood-pooling has primarily been investigated in a single subdivision of the knee extensor muscle group, mostly vastus lateralis (VL) (Ganesan et al., 2015; Kacin & Strazar, 2011; Lauver et al., 2020). Investigating multiple subdivisions of the knee extensor muscle group simultaneously could provide valuable information on potential intermuscular differences in the physiological response with LL-BFR and LL-FF exercise. Potential exercise-induced intermuscular physiological differences may translate to differences in physiological adaptation (i.e. muscle strength) in response to longitudinal training. The VL muscle is the largest, strongest, and most investigated muscle of m. quadriceps. Yet, the less investigated vastus medialis (VM) may play an important role in counterbalancing the laterally directed contractile force of the VL, which is of functional importance for patella tracking and prevention of patellofemoral pain (Neptune, Wright, & van den Bogert, 2000; Tang et al., 2001). No study to date has measured muscle excitability and microvascular oxygenation of both the VL and VM during BFR exercise performed to task failure.