| 1. |
- Ambrosio, Fabrisia, et al.
(författare)
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The effect of muscle loading on skeletal muscle regenerative potential : an update of current research findings relating to aging and neuromuscular pathology
- 2009
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Ingår i: American Journal of Physical Medicine & Rehabilitation. - Baltimore : Lippincott Williams & Wilkins. - 0894-9115 .- 1537-7385. ; 88:2, s. 145-155
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Forskningsöversikt (refereegranskat)abstract
- Skeletal muscle is a dynamic tissue with a remarkable ability to continuously respond to environmental stimuli. Among its adaptive responses is the widely investigated ability of skeletal muscle to regenerate after loading or injury or both. Although significant basic science efforts have been dedicated to better understand the underlying mechanism controlling skeletal muscle regeneration, there has been relatively little impact in the clinical approaches used to treat skeletal muscle injuries and wasting. The purpose of this review article is to provide an overview of the basic biology of satellite cell function in response to muscle loading and to relate these findings in the context of aging and neuromuscular pathology for the rehabilitation medicine specialist.
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| 2. |
- Andersson, Helena M., et al.
(författare)
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Neuromuscular fatigue and recovery in elite female soccer : effects of active recovery
- 2008
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Ingår i: Medicine & Science in Sports & Exercise. - : Ovid Technologies (Wolters Kluwer Health). - 0195-9131 .- 1530-0315. ; 40:2, s. 372-380
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To investigate the time course of recovery from neuromuscular fatigue and some biochemical changes between two female soccer matches separated by an active or passive recovery regime. METHODS: Countermovement jump (CMJ), sprint performance, maximal isokinetic knee flexion and extension, creatine kinase (CK), urea, uric acid, and perceived muscle soreness were measured in 17 elite female soccer players before, immediately after, 5, 21, 45, 51, and 69 h after a first match, and immediately after a second match. Eight players performed active recovery (submaximal cycling at 60% of HRpeak and low-intensity resistance training at < 50% 1RM) 22 and 46 h after the first match. RESULTS: In response to the first match, a significant decrease in sprint performance (-3.0 +/- 0.5%), CMJ (-4.4 +/- 0.8%), peak torque in knee extension (-7.1 +/- 1.9%) and flexion (-9.4 +/- 1.8%), and an increase in CK (+ 152 +/- 28%), urea (15 +/- 2), uric acid (+ 11 +/- 2%), and muscle soreness occurred. Sprint ability was first to return to baseline (5 h) followed by urea and uric acid (21 h), isokinetic knee extension (27 h) and flexion (51 h), CK, and muscle soreness (69 h), whereas CMJ was still reduced at the beginning of the second match. There were no significant differences in the recovery pattern between the active and passive recovery groups. The magnitude of the neuromuscular and biochemical changes after the second match was similar to that observed after the first match. CONCLUSION: The present study reveals differences in the recovery pattern of the various neuromuscular and biochemical parameters in response to a female soccer match. The active recovery had no effects on the recovery pattern of the four neuromuscular and three biochemical parameters.
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| 3. |
- Eliason, Gabriella, et al.
(författare)
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Physical performance and muscular characteristics in different stages of COPD
- 2009
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley-Blackwell Publishing Inc.. - 0905-7188 .- 1600-0838. ; 19:6, s. 865-870
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Tidskriftsartikel (refereegranskat)abstract
- This study has examined exercise capacity and muscle morphology in patients with different severities of chronic obstructive pulmonary disease (COPD). Twenty-three patients and 12 healthy matched controls were recruited. Based on the severity of airflow obstruction, patients were divided into two subgroups. Exercise capacity was determined using a 6-min walk test. Muscle fiber composition, fiber area and number of satellite cells/muscle fiber were determined in muscle biopsies using immunohistochemistry. A progressive decline in exercise capacity was noted with ascending disease severity. Furthermore, a correlation between reduction in exercise capacity and changes in muscle fiber composition was observed in COPD. The group with severe and very severe COPD had a lower proportion of type I and a higher proportion of type IIa fibers compared with the other groups. In severe and very severe COPD, a reduction in fiber area of type IIa fibers was also seen. The number of satellite cells/muscle fiber did not differ between the groups. In conclusion, a decline in exercise capacity occurs already in mild and moderate COPD, indicating that the 6-min walk test is a reliable indicator of disease severity. Furthermore, changes in skeletal muscle morphology are associated with disease severity while muscle regenerative capacity is not altered.
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| 4. |
- Eriksson, Anders, et al.
(författare)
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Skeletal muscle morphology in power-lifters with and without anabolic steroids
- 2005
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Ingår i: Histochemistry and Cell Biology. - : Springer Science and Business Media LLC. - 0948-6143 .- 1432-119X. ; 124:2, s. 167-175
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Tidskriftsartikel (refereegranskat)abstract
- The morphological appearance of the vastus lateralis (VL) muscle from high-level power-lifters on long-term anabolic steroid supplementation (PAS) and power-lifters never taking anabolic steroids (P) was compared. The effects of long- and short-term supplementation were compared. Enzyme-immunohistochemical investigations were performed to assess muscle fiber type composition, fiber area, number of myonuclei per fiber, internal myonuclei, myonuclear domains and proportion of satellite cells. The PAS group had larger type I, IIA, IIAB and IIC fiber areas (p<0.05). The number of myonuclei/fiber and the proportion of central nuclei were significantly higher in the PAS group (p<0.05). Similar results were seen in the trapezius muscle (T) but additionally, in T the proportion of fibers expressing developmental myosin isoforms was higher in the PAS group compared to the P group. Further, in VL, the PAS group had significantly larger nuclear domains in fibers containing > or = 5 myonuclei. The results of AS on VL morphology in this study were similar to previously reported short-term effects of AS on VL. The initial effects from AS appear to be maintained for several years.
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| 5. |
- Folkesson, Mattias, 1972-, et al.
(författare)
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Immunohistochemical changes in the expression of HSP27 in exercised human vastus lateralis muscle
- 2008
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Ingår i: Acta Physiologica. - : Blackwell Publishing. - 1748-1708 .- 1748-1716. ; 194:3, s. 215-222
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The role of HSP27 in the adaptive process of skeletal muscle to exercise, especially in humans, is not well understood. The objective of this study was to investigate immunohistochemical changes in HSP27 expression in human vastus lateralis muscle following resistance and endurance exercises.Methods: Two different exercise protocols were used: (1) one-leg ergometer cycling (EC, n = 6) consisting of two 30-min bouts at 40% and 75% of peak oxygen uptake, respectively, and (2) leg extension resistance exercise (RE, n = 9) including 10 sets of eight repetitions at a load corresponding to 70% of one maximal repetition (1RM). Immunohistochemistry using specific monoclonal antibodies was used to determine the location of HSP27 protein in muscle biopsies from human vastus lateralis.Results: Our results show that RE, but not EC, induced a significant appearance of scattered accumulations of HSP27 protein in muscle fibres from five of nine subjects. The number of fibres with accumulation of HSP27 in RE ranged from 0% to 32% with a mean of 6.3% of the total number of fibres.Conclusion: We conclude that this rapid HSP27 protein relocation after RE is an important player in the cellular remodelling of human muscle fibres in response to exercise involving high-force contractions, but not in response to endurance exercises.
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| 6. |
- Kadi, Fawzi, 1970-
(författare)
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Fysisk träning och telomerer
- 2008
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Ingår i: Svensk Idrottsforskning. - 1103-4629. ; :2, s. 20-21
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Kadi, Fawzi, 1970-
(författare)
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In response to Point: Counterpoint : "Satellite cell addition is/is not obligatory for skeletal muscle hypertrophy"
- 2007
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 103:3, s. 1105-1105
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this letter, the point: counterpoint issue (1, 5) is addressed solely by referring to studies in humans. The analysis of histological sections from skeletal muscle of power lifters with many years of practice leaves no doubt about the role of satellite cells as myonuclei donors in the hypertrophied muscle fibre. The larger the cross-sectional area of fibres, the higher the number of myonuclei per cross-section (2, 4). Importantly, the strong relationship between the cross-sectional area of fibres and the number of myonuclei (r = 0,86; p < 0.0001) is obtained with a range of areas between 2500 µm2 and 14000 µm2 (4). Existing myonuclei are able to sustain an initial hypertrophy of the muscle fibre as long as the transcriptional activity of existing myonuclei does not reach its maximum (2, 3, 5). Satellite cells become myonuclei donors when fibre size reaches the ceiling size (2, 3, 5). Additionally, we should not forget that satellite cells are also donors of myonuclei to newly generated myotubes (2, 4). The intensity of exercise and the initial fibre area of the subjects included in a training program are important factors governing whether daughter cells generated by satellite cell activation and proliferation provide new myonuclei to existing myofibres or to newly generated myotubes. Finally, in parallel with these events, some of the daughter cells can escape differentiation and facilitate renewal of the satellite cell pool. Efforts should be made to better understand key elements guiding the fate of satellite cells.
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| 8. |
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| 9. |
- Larsson, Barbro, 1952-, et al.
(författare)
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Surface electromyography and peak torque of repetitive maximum isokinetic plantar flexions in relation to aspects of muscle morphology
- 2006
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Ingår i: Journal of Electromyography & Kinesiology. - : Elsevier BV. - 1050-6411 .- 1873-5711. ; 16:3, s. 281-290
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the relationships between surface electromyography (EMG [Mean frequency of the power spectrum (MNF)]) and peak torque variables obtained during 100 maximum concentric plantar flexions with the right limb at 60 degrees s(-1) and different muscle morphological variables. Surface EMG was recorded from the right gastrocnemius lateralis and muscle biopsies were taken from the same site as the EMG electrodes were positioned. Muscle fibre area and fibre type composition were determined on serial muscle cross sections using both histochemistry (myofibrillar adenosine triphosphatase) and immunohistochemistry (monoclonal antibodies against specific myosin heavy chain isoforms). Forty-three female and nine male students participated in the study. Gastrocnemius lateralis contained predominantly type I fibres (50%) and type IIA fibres (40%) in both sexes and large individual differences were found. Principal component analysis (PCA) was used for the intercorrelation analyses, and projection to latent structures (PLS) was used for the multivariate regression analysis. MNF correlated positively with different fibre areas and with the proportion of type I fibres. Fibre areas and sex were the most important factors in the regression of maximum peak torque. High proportion of type I fibres and sex were the most important regressors of peak torque endurance normalised for lean body mass. More studies are needed to understand the complex interrelationships between intrinsic muscle properties and the frequency content of the surface EMG before theoretical models can be formulated that incorporate both fibre areas and fibre type proportions.
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| 10. |
- Mackey, A. L., et al.
(författare)
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Assessment of satellite cell number and activity status in human skeletal muscle biopsies
- 2009
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Ingår i: Muscle and Nerve. - : John Wiley & Sons. - 0148-639X .- 1097-4598. ; 40:3, s. 455-465
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Tidskriftsartikel (refereegranskat)abstract
- The primary aim of our study was to validate the assessment of myonuclear and satellite cell number in biopsies from human skeletal muscle. We found that 25 type I and 25 type II fibers are sufficient to estimate the mean number of myonuclei per fiber. In contrast, the assessment of satellite cells improved when more fibers were included. Second, we report that small differences in counting satellite cells using CD56 and Pax7 antibodies can be attributed to the different staining profiles. Third, we provide support for the use of Ki67 in evaluating the proportion of active satellite cells. We observed very few (up to 1.3%) active satellite cells in healthy adult skeletal muscle at rest, but they increased significantly (up to 7-fold) following muscle activity. This study provides valuable tools to assess the behavior of satellite cells, both in pathological conditions and in response to physiological stimuli.
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