| 1. |
- Alghadir, A. H., et al.
(författare)
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Effect of quadriceps and hamstrings muscle cooling on standing balance in healthy young men
- 2017
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Ingår i: Journal of Musculoskeletal and Neuronal Interactions - JMNI. - : JMNI. - 1108-7161. ; 17:3, s. 176-182
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The present study compared the effect of quadriceps and hamstring muscle cooling on standing balance in healthy young men.Methods: Thirty healthy young men (18-30 years) participated in the study. The participants were randomly assigned to three groups (n=10 each): quadriceps cooling (QC), hamstring cooling (HC), or control group (no cooling). Participants in the QC and HC groups received 20 minutes of cooling using a cold pack (gel pack), placed on the anterior thigh (from the apex of the patella to the mid-thigh) and the posterior thigh (from the base of the popliteal fossa to the mid-thigh), respectively. Balance score including unilateral stance was measured at baseline and immediately after the application of the cold pack.Results: No significant difference in the balance score was noted in any group after the application of the cold pack (p>0.05). Similarly, no significant differences in post-test balance score were noted among the three groups (p>0.05).Conclusions: Cooling of the quadriceps and hamstring muscles has no immediate effect on standing balance in healthy young men. However, longitudinal studies are warranted to investigate the long-term effects of cooling these muscles on standing balance.
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| 2. |
- Backman, Ludvig, et al.
(författare)
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Endogenous substance P production in the Achilles tendon increases with loading in an in vivo model of tendinopathy : peptidergic elevation preceding tendinosis-like tissue changes
- 2011
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Ingår i: Journal of Musculoskeletal and Neuronal Interactions - JMNI. - : International Society of Musculoskeletal and Neuronal Interactions. - 1108-7161. ; 11:2, s. 133-140
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To quantify the intratendinous levels of substance P (SP) at different stages of overload in an established modelfor Achilles tendinopathy (rabbit). Also, to study the distribution of the SP-receptor, the NK-1R, and the source of SP, in thetendon. Methods: Animals were subjected to the overuse protocol for 1, 3 or 6 weeks. One additional group served as unexercisedcontrols. Immunoassay (EIA), immunohistochemistry (IHC), and in situ hybridisation (ISH) were performed.Results: EIA revealedincreased SP-levels in the Achilles tendon of the exercised limb in all the experimental groups as compared to in thecontrols (statistically significant; p=0.01). A similar trend in the unexercised Achilles tendon was observed but was not statisticallysignificant (p=0.14). IHC and in ISH illustrated reactions of both SP and NK-1R mainly in blood vessel walls, but the receptorwas also found on tenocytes.Conclusions: Achilles tendon SP-levels are elevated already after 1 week of loading. This showsthat increased SP-production precedes tendinosis, as tendinosis-like changes occur only after a minimum of 3 weeks of exercise,as shown in a recent study using this model. We propose that central neuronal mechanism may be involved as similar trends wereobserved in the contralateral Achilles tendon.
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| 6. |
- Degens, H, et al.
(författare)
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Application of skinned singel muscle fibres to determine myofilament function in ageing and disease
- 2007
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Ingår i: Journal of Musculoskeletal and Neuronal Interactions - JMNI. - 1108-7161. ; 7:1, s. 56-61
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Tidskriftsartikel (refereegranskat)abstract
- The chemically skinned fibre is a suitable preparation to determine whether alterations in myofilament function contributeto muscle dysfunction during ageing and disorders such as chronic obstructive pulmonary disease (COPD). In this preparationthe sarcolemma is chemically permeabilized and the myofilament lattice kept intact, functioning under controlled near-phys-iological conditions. As force generating capacity is an important determinant of muscle function and is related to fibre cross-sectional area (FCSA), we compared several methods employed by researchers to determine FCSA. Specific tension, forcedivided by FCSA, has a co-efficient of variation of 27%, 37%, or 30% when the FCSA was measured from the width and depthassuming an elliptical circumference, the width assuming a circular circumference, and the width while the fibre was suspend-ed in the air, respectively. The last method showed the closest relation with the FCSA in histological sections. The velocity ofmaximal unloaded shortening (V0) varied with fibre type, with fibres expressing the ‚/slow (type I) myosin heavy chain(MyHC) isoform being the slowest and fibres expressing the IIb MyHC isoform the fastest. While muscle weakness experi-enced after surgery could not be explained by changes in specific tension or FCSA of individual fibres, the preparationrevealed significant changes in myofilament function during ageing and COPD.
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| 7. |
- Elam, Cecilia, et al.
(författare)
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Effects of age on muscle power, postural control and functional capacity after short-term immobilization and retraining.
- 2022
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Ingår i: Journal of musculoskeletal & neuronal interactions. - 1108-7161. ; 22:4, s. 486-497
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effect of lower limb immobilization and retraining on postural control and muscle power in healthy old and young men.Twenty men, nine old (OM:67.3±4.4 years) and eleven young (YM:24.4±1.6 years) underwent 2 weeks of unilateral whole-leg casting, followed by 4 weeks of retraining. Measures included center of pressure (CoP) sway length and area during single- and double-leg stance, maximal leg extensor muscle power, habitual and maximal 10-m gait speed, sit-to-stand performance, and 2-min step test.After immobilization, leg extension muscle power decreased by 15% in OM (from 2.68±0.60 to 2.29±0.63 W/kg, p<0.05) and 17% in YM (4.37±0.76 to 3.63±0.69 W/kg, p<0.05). Double-leg CoP sway area increased by 45% in OM (218±82 to 317±145 mm2; p<0.05), with no change in YM (p=0.43). Physical function did not change after immobilization but sit-to-stand performance (+20%, p<0.05) and 2-min step test (+28%, p<0.05) increased in OM following retraining. In both groups, all parameters returned to baseline levels after retraining.Two weeks of lower limb immobilization led to decreases in maximal muscle power in both young and old, whereas postural control was impaired selectively in old men. All parameters were restored in both groups after 4 weeks of resistance-based retraining.
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| 8. |
- Karlsson, Magnus K
(författare)
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Physical activity, skeletal health and fractures in a long term perspective.
- 2004
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Ingår i: Journal of Musculoskeletal and Neuronal Interactions - Jmni. - 1108-7161. ; 4:1, s. 12-21
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Tidskriftsartikel (refereegranskat)abstract
- Exercise during adolescence, especially during the pre-pubertal years, builds a skeleton with a high bone mineral density (BMD) and possibly a larger skeleton with a different skeletal architecture. This would lead to a stronger skeleton more resistant to trauma. These changes could be of biological significance for fracture reduction, if they were maintained into old age where fragility fractures exponentially rise. The Achilles heel of exercise is its cessation. Most BMD benefits achieved by exercise appear to be eroded with cessation of exercise. Reduced exercise intensity after a period of high activity, may maintain some residual BMD benefits into old age. A decreased fracture rate in the population could perhaps be achieved by promoting a physically active life style with lifelong high activity. But what happens if the activity in former athletes is reduced to the same level as in individuals who never exercised? The null hypothesis that exercise has no effect on fracture rates in old age cannot be rejected on the basis of any published, randomised, prospective data. Instead we have to rely on retrospective observational and case control studies, all hypothesis-generating, not hypothesis-testing. Existing data suggest that there could be a reduced fracture risk in former athletes. This notion may be correct, but consistently replicated sampling bias may produce the same observation and any biological explanation for this fracture reduction is unclear. Residual structural skeletal benefits, improved muscle strength, coordination and balance are all traits possibly maintained in former athletes after their active career. These traits may possibly reduce the number of fractures in later life.
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| 10. |
- Lerner, Ulf H
(författare)
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Deletions of genes encoding calcitonin/alpha-CGRP, amylin and calcitonin receptor have given new and unexpected insights into the function of calcitonin receptors and calcitonin receptor-like receptors in bone.
- 2006
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Ingår i: Journal of musculoskeletal & neuronal interactions. - 1108-7161. ; 6:1, s. 87-95
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that skeletal nerves fibers may play important roles in neuro-osteogenic interactions. This view is partly based upon information obtained from immunohistochemical studies, chemical and surgical denervation experiments and clinical observations in patients with stroke and spinal cord injury, indicating the presence of a network of nerve fibers in the skeleton and that defective signalling in skeletal nerve fibers affects remodelling of bone. This view is also supported by data showing that functional receptors for signalling molecules in skeletal nerve fibers are expressed in bone cells and that activation of these receptors leads to profound effects on bone forming osteoblasts and bone resorbing osteoclasts. Convincing evidence for a role of neuronal signalling in bone metabolism has been provided by gene deletion approaches in which it has been shown that leptin-sensitive and neuropeptide Y-sensitive receptors in hypothalamus are important for bone remodelling in mice. Recently, gene deletion experiments have shown that calcitonin gene-related peptide (CGRP), one of the neuropeptides present in skeletal nerve fibers, is an important physiological regulator of bone formation at the level of osteoblast activity. CGRP belongs to the calcitonin (CT) family of peptides also including CT, amylin and adrenomedullin, as well as the recently described intermedin and calcitonin receptor-stimulating peptide. These peptides utilize two seven transmembrane G protein-coupled receptors - the calcitonin receptor (CTR) and the calcitonin receptor- like receptor (CRLR) - which can dimerize with three different single transmembrane proteins, making up the RAMP family. Associations between RAMPs and either CTR or CRLR give rise to seven distinct, molecularly characterized, receptors for CT, CGRP, amylin and adrenomedullin. Deletions of the genes for ligands in the CT family of peptides and for one of the receptors have revealed unexpected findings that have changed our view on the role of these peptides in bone remodelling. It was anticipated that deletions of the CT/alpha-CGRP and CTR genes would lead to bone loss, since CT has been shown to inhibit bone resorption in vitro and in vivo and has been used to treat patients with excessive bone resorption. Surprisingly, it was found that CT/alpha-CGRP-/- and CTR+/- mice have increased bone mass due to increased bone formation. Mice with deletion of the amylin gene, however, exhibited bone loss due to enhanced bone resorption. Selective deletion of the alpha-CGRP gene also leads to bone loss, but due to decreased bone formation. Thus, our understanding of the role of the CT family of peptides has been changed dramatically and much more data have to be gained before we fully understand the roles these peptides have in bone biology.
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