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Designing for Lower Torso and Leg Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The large superficial and posterior gluteus maximus fills out the curves of the buttocks (see Figure 5.15-D). It varies in bulk person to person requiring product size and form adjustments. Its primary function is to extend the thigh at the hip joint. The gluteus maximus originates on the external surfaces of the sacrum, SI joint, and adjacent portion of the ilium. It inserts low on the posterior femoral trochanter and iliotibial tract. To locate and palpate the action of the gluteus maximus: (1) steady yourself with one hand on a chair, (2) place your other hand with your thumb on the lateral iliac crest and your fingers spanning over the top of your buttocks, just below the iliac crest, (3) lift your leg straight back, moving from the hip not the low back, (4) feel the muscle contract. Portions of the gluteus maximus also laterally rotate, abduct, and adduct the thigh. Additional small, superficial lower torso muscles act with the small muscles originating inside the pelvis to move and position the thigh. These small muscles typically do not affect product shape or function.
The Mechanics of Gait
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
During the loading response, normal limb alignment is a posture of instability. The vector is anterior to the hip and posterior to the knee, inducing a flexor torque at both joints. The action of the hip extensors and hamstrings and, more significantly, the gluteus maximus and adductor magnus preserves stance stability. At the knee, the stabilizing force is the quadriceps.
Effects of knee flexion angles in supine bridge exercise on trunk and pelvic muscle activity
Published in Research in Sports Medicine, 2020
Indy Man Kit Ho, Lai Ping Cindy Ng, Kin on Leonardo Lee, Tze Chung Jim Luk
When compared to other lower limb full weight-bearing exercises such as full squat or deadlift, double-leg supine bridge exercise (SBE) is widely used clinically, especially during the early rehabilitation of hip and knee injuries (Garrison et al., 2014; Philippon et al., 2011). Moreover, a recent study showed that single-joint exercises such as prone hip extension and simple SBE could produce higher activation on gluteus maximus when compared to certain multi-joint exercises such as squat (Macadam & Feser, 2019). Therefore, it is believed that simple closed-chain and partial weight-bearing exercise such as SBE can be a good starting drill for untrained or injured people to learn gluteal activation when compared to complex multi-joint movements. In addition, clinically SBE can be easily prescribed either on the ground or treatment plinth. All these justify why SBE is a popular rehabilitative exercise for enhancing the lumbopelvic stability and strengthen the posterior trunk and hip muscles (Choi et al., 2015; Ishida et al., 2011; Lim & Kim, 2013).
Effects of fatigue on hamstrings and gluteus maximus shear modulus in hip extension and knee flexion submaximal contraction task
Published in Sports Biomechanics, 2023
Ricardo Pimenta, Pedro Almeida, José P. Correia, Paula M. Bruno, João R. Vaz
Regarding active shear modulus assessment, two previous studies were conducted on two hamstring muscles (i.e., BFlh and ST) using SWE in isometric KF submaximal tasks (Mendes et al., 2018, 2020). The first assessed hamstrings’ active shear modulus across several submaximal intensities and noted that the ST generally showed a greater active shear modulus compared to BFlh, especially at low intensities (i.e., <40% of maximal voluntary isometric contraction, MVIC) (Mendes et al., 2018). The second found that after a KF fatigue task at 20% of MVIC, the active shear modulus of the ST decreases without changes in BFlh shear modulus, thus increasing the BFlh/ST ratio (Mendes et al., 2020). Together, these two studies indicate that BFlh/ST active shear modulus ratio is sensitive to both contraction intensity and fatigue. However, as the hamstrings shear modulus pattern seems to be different between KF and HE exercises (Bourne et al., 2017; Fernandez-Gonzalo et al., 2016; Ono et al., 2011; Schuermans et al., 2014), it should be interesting to examine whether these findings also apply to HE exercises. In addition, several aspects were not considered in the aforementioned studies. Firstly, passive muscle shear modulus was not assessed; thus, the resting state of the tested muscles on HE remains unclear. Secondly, only the BFlh and ST were examined, and the effect of fatigue was not tested between hip- and knee-dominant tasks in other hamstring muscles (i.e., SM and BFsh). Furthermore, it is well known that HE involves a great contribution from gluteus maximus (GM) (Neto et al., 2020), which has been reported to be crucial in the acceleration phase of sprinting, playing a key role in the forward orientation ground force (horizontal force) production (Dorn et al., 2012; Hamner & Delp, 2013). It should be noted that the main mechanism of hamstring strain injury is the sprint (Brooks et al., 2006). However, it is unknown whether fatigue could alter the GM passive and active shear modulus and be considered in a load sharing mechanism, which could be important in understanding hamstring strain injuries and developing rehabilitation strategies.
Peak Forces and Force Generating Capacities of Lower Extremity Muscles During Dynamic Tasks in People With and Without Chronic Ankle Instability
Published in Sports Biomechanics, 2022
Hoon Kim, Riann Palmieri-Smith, Kristof Kipp
A primary finding of the current study was that people with CAI generated greater peak gluteus maximus forces than people in the CON group across all tasks. More specifically, people with CAI generated on average approximately 24% greater peak gluteus maximus forces during all landing and cutting tasks. This finding agrees with previous studies, which reported that people with CAI exhibit compensatory muscle activations at proximal joints (DeJong et al., 2020; K. Kim et al., 2019; Rios et al., 2015). For example, H. Kim et al. (2019) observed greater activations of knee and hip joint muscles (e.g., vastus lateralis, adductor longus, gluteus maximus, and gluteus medius) in CAI patients during the transition phase (i.e., after landing and before takeoff) of landing/cutting tasks (K. Kim et al., 2019). Similarly, Rios et al. (2015) reported that people with CAI activated muscles at proximal joints more during the single-leg stance phase of ball-kicking tasks than a group of healthy controls (Rios et al., 2015). Furthermore, DeJong et al. (2020) observed that the difference in ultrasound-based gluteus maximus muscle thickness, which is a purported surrogate of muscle activation, between resting and exercise conditions during a dynamic balance task were greater in a group of people with CAI than a group of healthy controls (DeJong et al., 2020; Mangum et al., 2018). The authors of these studies suggested that people with CAI adopt greater activation of proximal muscles as a compensatory strategy that aims to improve postural control and mitigate neuromuscular deficits at the ankle joint (DeJong et al., 2020; K. Kim et al., 2019; Rios et al., 2015). However, since muscle activation assessed via EMG or ultrasound only provide indirect, and somewhat tenuous, information about muscle forces, the current study provides more direct evidence that compensatory muscle function in people with CAI also extends to the generation of force in proximal muscles. Specifically, the greater gluteus maximus force in the current study bolsters previous assertions that people with CAI stabilise proximal joints and segments across the kinetic chain to help stabilise distal joints (Webster et al., 2016). This interpretation is supported by the fact that the gluteus maximus has an important role during the performance of athletic tasks because it prevents excessive hip adduction, trunk flexion angle, and femoral internal rotation angles, which may deleteriously affect ankle inversion through kinematic coupling (Buckthorpe et al., 2019; MacKinnon & Winter, 1993). Collectively, these findings therefore suggest that people with CAI exhibit neuromuscular differences in the function of proximal muscles, which may reflect a strategy to compensate for deficits at the ankle joint. Despite these findings, further studies should investigate association between proximal muscle forces and ankle joint kinematics to provide direct evidence about the compensatory mechanism.