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The Lower Extremities
Published in Melanie Franklyn, Peter Vee Sin Lee, Military Injury Biomechanics, 2017
The thigh encompasses the area between the pelvic bone and the knee. The femur, the largest and heaviest bone of the body, resides in the thigh and transmits the body weight from the pelvis to the tibia. The cylindrical shaped femoral head, which lies at the proximal end of the femur, articulates with the acetabulum. The femoral head is connected to the femoral shaft by a narrow neck, which lies at an approximate angle of 125° with the shaft (Moore et al. 2011). The distal portion of the femur diverges into a medial and a lateral condyle. The femoral condyles articulate with the proximal tibia condyles to form the knee joint.
Load-dependent mechanical demands of the lower extremity during the back and front squat
Published in Journal of Sports Sciences, 2020
John Krzyszkowski, Kristof Kipp
The squat is a commonly prescribed exercise in strength and conditioning programmes to develop power and strength in the lower extremity for sports such as track and field, volleyball, weightlifting, and powerlifting (Escamilla, Fleisig, Zheng et al., 2001; Schoenfeld, 2010). Both lower body strength and power are important physical qualities that improve athletic performance when developed properly. In particular, the squat strengthens the muscles of the thigh and hip, which are important contributors to dynamic movements such as weightlifting, sprinting, and jumping. Greater maximal squat performance is correlated with faster sprint times (Chaouachi et al., 2009; Comfort et al., 2012, 2014; McBride et al., 2009) higher vertical jump heights (Comfort et al., 2014; Nuzzo et al., 2008; Wisløff et al., 2004), and greater maximal power outputs (Baker & Steven, 1999). In addition, several studies suggest that improving squat performance improves various aspects of athletic performance (Adams et al., 1992; Chelly et al., 2009; Comfort et al., 2012; Seitz et al., 2014).
The time-continuous association between turnout and axial joint moments in the competitive Irish dance ‘fly’ landing
Published in Sports Biomechanics, 2021
Kelsi Wallace, Sofia Kalogeropoulou, Peter Lamb
Following the capture of the trials, marker reconstruction and labelling was performed in Vicon Nexus v2.7 (Vicon Motion Systems Ltd., Oxford, UK). A biomechanical model of the right leg and pelvis was created using Visual3D Professional v6 (C-motion, Inc., Germantown, MA). Local coordinate systems for the pelvis, thigh, shank, and foot were derived from the standing calibration trial. A functional hip joint was calculated based on a dynamic calibration movement using the Gillette algorithm (Schwartz & Rozumalski, 2005). Markers placed on the left and right iliac crests and greater trochanters were used to define the pelvis coordinate system. Left and right iliac crest and posterior superior iliac spine markers were used for tracking. The thigh was defined by the functional hip joint centre, greater trochanter and medial and lateral femoral epicondyles. Four markers were placed along the lateral aspect of the thigh in a staggered pattern for tracking. The shank was defined using medial and lateral femoral epicondyles and medial and lateral malleoli. Four markers placed along the lateral and anterior aspect of the shank were used for tracking. A virtual foot was created for ankle kinematics with its coordinate system aligned with the shank. Markers placed on the calcaneus, lateral aspect of the fifth metatarsal head and on the top of the shoe above the second metatarsal head were used for tracking the virtual foot. For kinetics, the foot was defined using the medial and lateral malleoli markers and the fifth metatarsal marker with the same markers used for tracking as the virtual foot. Inverse dynamics calculations were performed to determine knee and ankle joint moments. Internal joint moments were calculated; for clarity, internal axial moments indicate internal joint moments in the direction of internal rotation. Joint angles were calculated using an XYZ rotation sequence, and joint moments were resolved into the proximal segment’s coordinate system. Further processing and analyses were done in MATLAB R2020b (The MathWorks Inc., Natick, MA). Landing durations were defined according to foot contact on the force plate (70 N threshold). All trials were time-normalised to 101 frames. Three trials from one participant were removed due to errors in force measurement and six trials from another participant were removed due to occluded pelvis markers.