Search results for "Sports"
showing 10 items of 4839 documents
A reanalysis of spinal motion during vibration
1987
Calibrated film of the motion of the lumbar spine during vibration was reanalysed, making use of a number of computer based techniques to improve accuracy and reduce measurement noise. The results demonstrated resonant behaviour at about 4 Hz and indicated that at vibration levels of the order of 1 m/s2 there exists bending of the order of 1° (peak to peak) between adjacent vertebrae in the lumbar spine. The bending is complex and involves phase differences along the spine and possibly a rocking motion of the pelvis.
Profilin 1 Negatively Regulates Osteoclast Migration in Postnatal Skeletal Growth, Remodeling, and Homeostasis in Mice
2019
Profilin 1 (Pfn1), a regulator of actin polymerization, controls cell movement in a context-dependent manner. Pfn1 supports the locomotion of most adherent cells by assisting actin-filament elongation, as has been shown in skeletal progenitor cells in our previous study. However, because Pfn1 has also been known to inhibit migration of certain cells, including T cells, by suppressing branched-end elongation of actin filaments, we hypothesized that its roles in osteoclasts may be different from that of osteoblasts. By investigating the osteoclasts in culture, we first verified that Pfn1-knockdown (KD) enhances bone resorption in preosteoclastic RAW264.7 cells, despite having a comparable num…
Screw‐in‐screw fixation of fragility sacrum fractures provides high stability without loosening—biomechanical evaluation of a new concept
2020
Surgical treatment of fragility sacrum fractures with percutaneous sacroiliac (SI) screw fixation is associated with high failure rates. Turn-out is detected in up to 20% of the patients. The aim of this study was to evaluate a new screw-in-screw implant prototype for fragility sacrum fracture fixation. Twenty-seven artificial hemipelvises were assigned to three groups (n = 9) for instrumentation of an SI screw, the new screw-in-screw implant prototype, ora transsacral screw. Before implantation, a vertical osteotomy was set in zone 1 after Denis. All specimens were biomechanically tested to failure in upright position. Validated setup and test protocol were used for complex axial and torsi…
Range of Motion and Injury Occurrence in Elite Spanish Soccer Academies. Not Only a Hamstring Shortening-Related Problem.
2020
Sanz, A, Pablos, C, Ballester, R, Sanchez-Alarcos, JV, and Huertas, F. Range of motion and injury occurrence in elite Spanish soccer academies. Not only a hamstring shortening-related problem. J Strength Cond Res 34(7): 1924-1932, 2020-Age-related development of range of motion (ROM) during an active hip flexion (active straight leg raise) and its relationship with hamstring injury occurrence were examined in 1657 young male soccer players (9-18 years of age). Age-related differences in ROM showed a significant decrease from U9 to U11 (p = 0.001), from U11 to U13 (p0.005), and from U9 to U13 (p0.001), whereas ROM increased from U13 to U15 and from U13 to U18 (both p's0.001). Interestingly, …
Inter- and intra-tester reliability of selected clinical tests in examining patients with early phase lumbar spine and sacroiliac joint pain and dysf…
2010
AbstractOf all patients with low back pain (LBP), 85% are diagnosed as “non-specific lumbar pain”. It has been postulated that the only reliable test is a straight leg raise test for detecting sciatic pain, and for other diagnostic subgroups, tests are of varying value. Only a few standardized tests exist to test function, inspection, mobility, pain, muscle flexibility or stability for patients with early phase lumbar spine and sacroiliac joint pain and dysfunction in the non-laboratory setting. The aim of this study was therefore to examine the inter- and intra-tester reliability of selected standardized clinical tests. Fifteen eligible, consecutive and voluntary LBP patients (aged 18–56 y…
Enhanced prolylhydroxylase activity in the posterior annulus fibrosus of canine intervertebral discs following long-term running exercise
2010
The effect of long-term excercise on the intervertebral disc collagen concentration (hydroxyproline), collagen-synthesizing enzymes (prolyl-4-hydroxylase, PH, and galactosyl-hydroxylysyl glucosyltransferase, GGT) and hydroxypyridinium crosslinks was studied in ten female beagle dogs. The dogs were run on a treadmill for 1 year starting at the age of 15 weeks. The daily running distance was gradually increased to 40km, which distance the dogs ran for the final 15 weeks. Ten untrained dogs from the same breeding colony served as controls. The nucleus pulposus and anterior and posterior halves of the annulus fibrosus of C2-3, T10-12, L4-5 disc segments were analysed. Crosslinks were measured f…
Kinematics of the ulna during pronation and supination in a cadaver study: implications for elbow arthroplasty
2003
Objective. Aim of this study was to exactly describe and quantify kinematics of the ulna during pro- and supination. Design. Biomechanical study in fresh frozen cadavers. Background. A previous MRI study revealed a varus/valgus motion of the ulna averaging 7.1° during pro-/supination. Axial rotation, however, could not be quantified. Methods. Sixteen arms were examined in a new apparatus that fixed the humerus on a template and allowed forearm rotation. Motion of a Kirschner wire placed in the ulna was recorded in steps of 30° by two perpendicularly arranged charge coupled device cameras during pro- and supination. Results. From supination to pronation the ulna showed a semi-lunar evasive m…
Effects of internal kinetics and muscle activity during the wide and narrow barbell back squat
2017
Lahti, J. 2017. Effects of internal kinetics and muscle activity during the wide and narrow barbell back squat. Sports biology department, University of Jyväskylä. Master’s thesis. p. 102 (4 attachments). Introduction. The barbell back squat (BBS) is a commonly utilized strength exercise to support general preparedness for the demands in multiple sports. Recently, studies have shown various strength training exercises have the potential to recruit the regions of the hamstrings differently. Specifically, it is unknown if changing stance width under conditions where forward knee movement is restricted engages the hamstring regions differently and how this corresponds with measured 3-D net joi…
Improving the cementation of the tibial component in knee arthroplasty : a study of four techniques in the cadaver.
2021
Aims The main objective of this study is to analyze the penetration of bone cement in four different full cementation techniques of the tibial tray. Methods In order to determine the best tibial tray cementation technique, we applied cement to 40 cryopreserved donor tibiae by four different techniques: 1) double-layer cementation of the tibial component and tibial bone with bone restrictor; 2) metallic cementation of the tibial component without bone restrictor; 3) bone cementation of the tibia with bone restrictor; and 4) superficial bone cementation of the tibia and metallic keel cementation of the tibial component without bone restrictor. We performed CT exams of all 40 subjects, and mea…
Die Sonographie der Lendenwirbelsäule und des lumbosakralen Überganges - Sonoanatomie und Möglichkeiten der sonographisch gesteuerten Facettengelenks…
2008
QUESTION Is sonography helpful in facet joint infiltration of the lumbar spine? METHOD The sonoanatomy of the lumbar spine and the of lumbosacral junction was examined and described in a skeleton and in 10 volunteers. One representative cross section and 3 longitudinal sections were defined. According to these results (no neurological symptoms) the possibilities of ultrasound guided infiltration of the facet joints was examined in 78 patients (36 female, 42 male, average age 55 y., 38-78 y.) with chronic low back pain and increase of pain by hyperextension. 5 ml Carbostesin partially in combination with steroids were applied to each joint. In all cases the tip of the syringe could be placed…