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Blood flow
Published in Peter R Hoskins, Kevin Martin, Abigail Thrush, Diagnostic Ultrasound, 2019
Changes in posture can lead to large changes in hydrostatic pressure in the venous system. When a person is lying supine, there is a relatively small pressure difference between the venous pressure at the ankle and at the right atrium. However, when standing there is a column of blood between the right atrium and veins at the ankle and this produces a significant pressure gradient which has to be overcome in order for blood to be returned to the heart. This can be achieved by the calf muscle pump mechanism assisted by the presence of the venous valves. The muscle compartments in the calf contain the deep veins and venous sinuses that act as blood reservoirs. When the deep muscles of the calf contract, thus causing compression of the veins, blood flow is forced out of the leg and prevented from returning by the venous valves. This also creates a pressure gradient between the superficial and deep veins in the calf causing blood to drain from the superficial to the deep venous system. If there is significant failure of the venous valves in either the superficial or deep venous system, reflux will occur, leading to a less-effective muscle pump and a higher pressure than normal in the veins following calf muscle contraction and relaxation. This may eventually lead to the development of venous ulcers.
Body Systems: The Basics
Published in Karen L. LaBat, Karen S. Ryan, Human Body, 2019
Some muscle features are relatively consistent from one muscle to the next. Muscles generally have a red or pink, “meaty” muscle belly, which is relatively thicker and at the muscle center. Muscle fibers form the belly. A tough thick band—a tendon; or a flat sheet—an aponeurosis, anchors the muscle (most often to bones) on either end. These two anchoring structures are formed from opaque, non-contractile connective tissue. They are the accumulation of all the fine connective tissue strands and coverings described in the five levels of muscle structure. While tendons are sturdy connections that facilitate motion, they are vulnerable to damage. Tendonitis is an inflammation (a combination of pain, swelling, and warmth in the tissues) or irritation of a tendon caused by repetitive motions or damage from minor impacts. If an athlete ruptures his/her Achilles tendon, which attaches the calf muscle to the heel bone (calcaneus), the result is pain and immediate loss of strength. Wearable products have been developed as aids in rehabilitation (the restoration of satisfactory function) for both tendonitis and tendon ruptures.
Bioinspired Nanomaterials for Bone Regeneration
Published in Šeila Selimovic, Nanopatterning and Nanoscale Devices for Biological Applications, 2017
Stress shielding and particulate wear are potential concerns with the use of non-degradable polymers such as poly(methyl methacrylate) (PMMA). In an attempt to control the degradation profile and improve the stability of the carrier against soft tissue compression, poly(lactide-co-glycolide) (PLGA) sponges or granules have been used to deliver rhBMP-2 for bone repair [5]. rhBMP-2-impregnated porous PLGA particles, implanted intramuscularly in nude mice, induced greater formation of new bone compared with active demineralized bone allograft [6]. Open-cell poly(L-lac-tide) (PLA) has been used to induce transverse process fusion in a canine model [7]. Recently, low-molecular-weight (LMW) PLGA, as a biodegradable slow delivery system for rhBMP-2, has been tested in the calf muscle of Wistar rats [5]. LMW PLGA accelerated the resorption rate, which in turn released rhBMP-2 at a faster rate, resulting in new bone formation 3 weeks after implantation [5]. To accelerate the resorption rate of the carrier, gelatin sponge coated with PLGA polymer has been used as a delivery system for rhBMP-2 to induce bone formation in the tibial diaphysis of dogs with internal plate fixation [8]. A major drawback of coated gelatin sponge is the need for a second surgical procedure to remove the internal fixation plate.
Validity, reliability, and normative data on calf muscle function in rugby union players from the Calf Raise application
Published in Sports Biomechanics, 2022
Kim Hébert-Losier, Te Manawa Ngawhika, Nicholas Gill, Carlos Balsalobre-Fernandez
This study was limited to male rugby union athletes and the results should not be generalised to female rugby union or sevens’ athletes given their unique requirements (Clarke et al., 2017; Sella et al., 2019). Although the data have the potential to inform the clinical management of injured players, our study involved uninjured players only to establish benchmark values and normative reference values. Therefore, individuals with a current Achilles tendon or calf muscle injury were excluded, and future research is needed to confirm the usefulness of the proposed calf muscle testing battery to establish the extent of injuries, track rehabilitation progress, and inform return-to-play decisions in rugby union. Finally, a set external load of 35 kg was used for the weighted power test based on prior research (Silbernagel et al., 2006), for ease of implementation, and to set a common benchmark load. Future work is required to determine whether implementing a relative load (e.g., percentage of body mass) would provide more meaningful outcomes than using an absolute load for rugby union players and ascertain generalisation across ages, levels, genders, and playing positions.
Contribution of the tibialis posterior and peroneus longus to inter-segment coordination of the foot during single-leg drop jump
Published in Sports Biomechanics, 2020
Hiroshi Akuzawa, Atsushi Imai, Satoshi Iizuka, Naoto Matsunaga, Koji Kaneoka
This study has some limitations. First, the sample size was small. Eleven participants might be insufficient to demonstrate a clinically meaningful correlation between TP and PL muscle activity and joint coordination of the foot segments. However, this is the first study to analyse the correlation between the calf muscle activities and the inter-segment coordination of the foot. Only a few studies have investigated muscle activity of the deep calf muscles using fine-wire electrodes and inter-segment coordination of the foot using the modified vector coding technique, respectively (Chang et al., 2008; Murley et al., 2009, 2014; Ringleb et al., 2007; Takabayashi et al., 2018). Thus, the results of this study are meaningful even though sample size is small. Second, this study is an observational study with healthy subjects. The result of this study can only speculate possibility of relationship between inter-segment pattern difference and injury, or clinical importance of the TP and PL muscle function for foot motion. Further prospective study is required to clarify them.
Effects of wearing lower leg compression sleeves on locomotion economy
Published in Journal of Sports Sciences, 2018
With respect to effects specifically utilizing lower leg compression garments we could only find five studies (Bieuzen et al., 2014; Del Coso et al., 2014; Menetrier, Mourot, Bouhaddi, Regnard, & Tordi, 2011; Sambaher, Aboodarda, Silvey, Button, & Behm, 2016; Stickford, Chapman, Johnston, & Stager, 2015). Muscular performance (including countermovement jump) and physiological variables did not differ between a calf compression and a control group wearing regular athletic socks after a half-ironman triathlon race (Del Coso et al., 2014). In contrast, 48 h after finishing simulated trail races of 5.2 km, athletes recovered faster when they utilized leg compression, as revealed by countermovement jumping height (Bieuzen et al., 2014). Due to large inter-individual differences in responses to calf compression, no systematic effects regarding running economy or gait variables could be observed during running at three different speeds (Stickford et al., 2015). Although tissue oxygen saturation of the gastrocnemius muscle was found to be higher after exercise with calf compression, running performance related benefits could not be verified (Menetrier et al., 2011). Only one of the aforementioned studies that utilized lower leg compression sleeves applied SEMG measurements on calf muscles. Contrary to the other studies, the participants were asked to perform a fatigue protocol of continuous drop jumps until task failure (Sambaher et al., 2016). One of the main outcomes was that the lower leg compression group revealed increased skin temperature as compared with controls. However, calf muscle SEMG did not differ between groups.