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Designing for Lower Torso and Leg Anatomy
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
The tibialis anterior is the largest muscle at the front of the leg. It extends (dorsiflexes) the ankle and produces subtle contours of the anterior leg. The anterior leg muscles are active if you “walk on your heels.” When the tibialis anterior is weak, the foot “drops” while walking, increasing risks for tripping and falling and increasing the energy demands of walking. AFOs are frequently used for foot drop to keep the foot at a 90° angle with the anatomical leg and make walking safer and easier. Fibularis longus (a long, narrow muscle) extends from the fibular head (a prominence of the proximal fibula) around the posterior of the lateral ankle to the bottom of the foot near the big toe. Feel the fibularis longus’ action: (1) place your hand over the mid-portion of the muscle on the outside of your leg, (2) raise the outside edge of your foot off the floor to feel the muscle contract. Read more about ankle, foot, and toe muscles in Chapter 8.
Fundamentals of human gait and gait analysis
Published in Ivan Birch, Michael Nirenberg, Forensic Gait Analysis, 2020
Ambreen Chohan, Jim Richards, David Levine
Toe off occurs at approximately 60% of the gait cycle, and marks the transition from the stance phase to the swing phase of gait. Toe off is also sometimes referred to as terminal contact, as some pathologies can result in parts of the foot other than the toes being the last to leave the ground during walking. Ankle: Just after toe off, the ankle reaches peak plantarflexion. The calf muscles have relaxed before toe off, and tibialis anterior now dorsiflexes the foot to clear the ground during the swing phase of gait.Knee: By toe off, the knee has flexed to around half its peak swing phase amount. During this phase of the gait cycle the lower limb acts as a double pendulum, with knee flexion resulting from hip flexion as the foot is left behind. The eccentric contraction of rectus femoris prevents the knee from flexing excessively at higher walking speeds (Nene et al. 1999).Hip: The hip continues to undergo flexion as the foot leaves the ground, as the result of a combination of gravity, passive soft tissue tension and muscle contraction.Trunk: After toe off, the trunk, shoulders and arms all begin to move from their rotated positions back towards neutral positions, as the trunk rises and moves towards the side of the now supporting lower limb.
Biomechanical Adaptation in Ice Hockey Skating
Published in Youlian Hong, Routledge Handbook of Ergonomics in Sport and Exercise, 2013
David J. Pearsall, René A. Turcotte, Marc C. Levangie, Samuel Forget
During the swing or recovery phase, muscles contract to reposition the leg in proper position for the next stride. The sEMG activity of the adductor magnus muscle peaks at roughly 70 per cent of MDC during this phase, as it is the principal muscle responsible for the adduction of the lower limb (Chang et al., 2009). sEMG activity of the tibialis anterior muscle peaks during the swing phase, as it is responsible for dorsi flexing the ankle, for skate clearance and precontact stability (Dewan et al., 2004).
Lower limb muscle activation patterns in ice-hockey skating and associations with skating speed
Published in Sports Biomechanics, 2021
Sami Kaartinen, Mika Venojärvi, Kim J Lesch, Heikki Tikkanen, Paavo Vartiainen, Lauri Stenroth
Previous studies of muscle activity during skating in ice-hockey have indicated that the gluteus maximus (Pearsall et al., 2000) and the vasti muscles are active during the propulsion phase to extend, abduct and externally rotate the hip and extend the knee, respectively (Buckeridge et al., 2015; Chang et al., 2009). Hamstring muscles are reported to be most active during the gliding phase (isometric phase) of skating to increase the stiffness of the knee joint with co-activity of knee extensors (De Boer et al., 1987). Additionally, the biceps femoris shows high activity also during the propulsion phase in ice-hockey skating when extension of the hip occurs (Chang et al., 2009). The activity of the tibialis anterior is at its highest during the gliding phase to stabilise the ankle and during the recovery phase to dorsiflex the ankle (Goudreault, 2002).
Prevalence of sleep disorders and sleep problems in an elite super rugby union team
Published in Journal of Sports Sciences, 2019
Ian C. Dunican, Jennifer Walsh, Charles C. Higgins, Maddison J. Jones, Kathleen Maddison, John A. Caldwell, Hillman David, Peter R. Eastwood
Sleep studies were performed as per American Academy of Sleep Medicine (AASM) recommendations (Berry et al., 2012). Electroencephalogram (EEG), electrooculogram (EOG) and chin electromyogram (EMG) were measured using surface electrodes. Respiration was monitored with nasal prongs, an oronasal thermistor and thoracic and abdominal respiratory bands. Blood oxygen saturation (SaO2) and heart rate were monitored continuously from a pulse oximeter on the index finger and Electrocardiography (ECG). Leg movements were monitored by EMG electrodes placed over the tibialis anterior muscle. A position sensor, microphone and a live video feed via an infrared camera were used to monitor body position and snoring. A sleep technician monitored the recordings and video in each room for the duration of the study. Data were acquired using Compumedics Grael (Compumedics, Victoria, Australia) system and scored by an experienced sleep technician using Profusion (PSG4) software according to the AASM 2012 version 2.0 rules for the scoring of sleep and associated events (Berry et al., 2012).
Lower extremity biomechanics and muscle activity differ between ‘new’ and ‘dead’ pointe shoes in professional ballet dancers
Published in Sports Biomechanics, 2021
Jessica Aquino, Tal Amasay, Sue Shapiro, Yi-Tzu Kuo, Jatin P. Ambegaonkar
Furthermore, this inability to maintain stable posture may increase demands on the tibialis anterior muscle. Accordingly, we found that dancers also exhibited higher RMS-%MVC of the tibialis anterior muscle during arabesque in ‘dead’ pointe shoes, which could have resulted from the dancer having to work harder to maintain the balancing position. An increased activation of the tibialis anterior muscle during pointe suggests that the participant was likely compensating for lack of support in the pointe shoe which may eventually cause the participant to begin ‘falling over’ the pointe shoe or having an increased plantar flexion angle. The tibialis anterior muscle is responsible for dorsiflexion at the ankle and inversion. It is an antagonist to the peroneus longus, gastrocnemius and soleus as well as a synergist to the posterior tibialis during inversion. When one muscle fatigues, the surrounding muscles must compensate to maintain a certain posture or complete a certain movement. So, when the posterior tibialis muscle fatigues, the tibialis anterior compensates to stabilise the ankle joint during inversion. Repetitively increased muscle activation may lead to a quicker onset of fatiguing of the ankle stabiliser muscles which may lead to chronic tendon injuries, ankle instability and other ankle injuries ((Hopkins et al., 2012; Kannus, 1997). In ‘dead’ pointe shoes, our participants had higher muscle activity while performing arabesque and not in relevé. This could be related to nature of the arabesque task, which requires the dancer to stabilise on one leg. Higher level of muscle activity during arabesque in ‘dead’ pointe shoes may lead to chronic tendon and ankle injuries as well ankle instability.