Endre søk
Begrens søket
1234 101 - 150 of 191
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 101. Lexell, Jan
    et al.
    Downham, David
    Department of Physical Medicine, Umeå University.
    Sjöström, Michael
    Department of Neurology, Umeå university.
    Distribution of different fibre types in human skeletal muscles: A statistical and computational model for the study of fibre type grouping and early diagnosis of skeletal muscle fibre denervation and reinnervation1983Inngår i: Journal of the Neurological Sciences, ISSN 0022-510X, E-ISSN 1878-5883, Vol. 61, nr 3, s. 301-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To define fibre type grouping in terms of random and non-random arrangements of the two fibre types, type 1 (ST) and type 2 (FT), we adopted the measure of counting the number of "enclosed fibres". The statistical properties of the number of enclosed fibres, and the number and size of groups of enclosed fibres were studied in computer-simulated muscle cross-sections, using a model based upon hexagonal-shaped fibres. The effects on the results of differences in the sizes of the muscle fibres were considered. The applicability of the model, and the derived results and methods of analysis were tested on 10 samples from a cross-section of a whole human muscle. The results show that the model can be applied to various shapes and sizes of muscle samples and various sizes of muscle fibres. The number of enclosed fibres within a muscle sample is the best of the three measures of non-randomness considered. A test is also described for assessing whether or not the observed number of enclosed fibres is random at a given significance level.

  • 102. Lexell, Jan
    et al.
    Downham, David
    Department of Physical Medicine, Umeå University.
    Sjöström, Michael
    Department of Neurology, Umeå university.
    Distribution of different fibre types in human skeletal muscles: A statistical and computational study of the fibre type arrangement in m. vastus lateralis of young, healthy males1984Inngår i: Journal of the Neurological Sciences, ISSN 0022-510X, E-ISSN 1878-5883, Vol. 65, nr 3, s. 353-65Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To test whether the arrangement of fibre types in the human muscle (m. vastus lateralis) from clinically healthy and young males can be regarded as random, fascicles at different parts of the muscle and with different fibre type proportions were studied. The randomness of the arrangement of fibre types was assessed by the number of enclosed fibres in a fascicle and, on the basis of a model, tested by simulating muscle cross-sections using a microcomputer. The fibre type proportion was found to vary within a fascicle, so the original model for the test of randomness was modified to allow for different fibre type proportions on the border of the fascicle and internally. The effect of different sizes of the fibre types was also considered. The various aspects considered had only a marginal effect on the original model. For this muscle (m. vastus lateralis) the arrangement of fibre types was therefore considered random. Thus, a sample from this muscle, taken from individuals of the same sex and age group, can be tested for non-randomness, as an indication of a successive denervation and reinnervation process

  • 103. Lexell, Jan
    et al.
    Downham, David
    Department of Physical Medicine, Umeå University.
    Sjöström, Michael
    Department of Neurology, Umeå university.
    Distribution of different fibre types in human skeletal muscles: fibre type arrangement in m. vastus lateralis from three groups of healthy men between 15 and 83 years1986Inngår i: Journal of the Neurological Sciences, ISSN 0022-510X, E-ISSN 1878-5883, Vol. 72, nr 2-3, s. 211-22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of age on the fibre type arrangement in the human muscle m. vastus lateralis were studied. There were 10, 6 and 8 healthy men in the three age-groups with means 24, 52 and 77 years, respectively. For each fascicle considered, the numbers of type 1 (ST) and type 2 (FT) fibres on the boundary and internally, and the numbers of enclosed fibres of either type, were counted. The randomness of the fibre type arrangement was considered in terms of the numbers of enclosed fibres and assessed by a Monte Carlo significance test. Fibre type grouping was shown to increase with increasing age. The proportion of type 2 fibres on the boundary of a fascicle was consistently greater than internally, but the difference was less pronounced in the old group. It is argued that the process of denervation and reinnervation of individual fibres has started before the age of 50, is a major factor in a progressive reduction of fibres with increasing age and is probably caused by a continuous loss of motor neurons in the spinal cord.

  • 104. Lexell, Jan
    et al.
    Downham, David
    Department of Physical Medicine, Umeå University.
    Sjöström, Michael
    Department of Neurology, Umeå university.
    Morphological detection of neurogenic muscle disorders: can statistical methods aid diagnosis?1987Inngår i: Acta Neuropathologica, ISSN 0001-6322, E-ISSN 1432-0533, Vol. 75, nr 2, s. 109-15Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The light microscopical observation of groups of histochemically similar muscle fibres, referred to as fibre-type grouping, is commonly considered to be evidence of a denervation and reinnervation process affecting the spinal motor neurons or the peripheral nerves. It can be difficult to assess whether such groups have occurred by chance or are due to a slowly progressive pathological process in an early stage of development. Consequently, there is a need for one or more objective methods for assessing the fibre-type arrangement in healthy and diseased human muscles. The purposes here are to review the methods for the detection of fibre-type grouping that have been published in the last two decades, to describe some unsolved problems, and to indicate some likely lines of development

  • 105. Lexell, Jan
    et al.
    Downham, David Y
    Department of Rehabilitation, Lund University Hospital, Sweden.
    How to assess the reliability of measurements in rehabilitation2005Inngår i: American Journal of Physical Medicine & Rehabilitation, ISSN 0894-9115, E-ISSN 1537-7385, Vol. 84, nr 9, s. 719-23Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To evaluate the effects of rehabilitation interventions, we need reliable measurements. The measurements should also be sufficiently sensitive to enable the detection of clinically important changes. In recent years, the assessment of reliability in clinical practice and medical research has developed from the use of correlation coefficients to a comprehensive set of statistical methods. In this review, we present methods that can be used to assess reliability and describe how data from reliability analyses can aid the interpretation of results from rehabilitation interventions.

  • 106. Lexell, Jan
    et al.
    Dutta, C
    Geriatrics Program, National Institute on Aging, National Institutes of Health, Bethesda.
    Hadley, EC
    Geriatrics Program, National Institute on Aging, National Institutes of Health, Bethesda.
    Sarcopenia and physical performance in old age: overview1997Inngår i: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 5, nr Supplement, s. S5-S9Artikkel i tidsskrift (Fagfellevurdert)
  • 107. Lexell, Jan
    et al.
    Flansbjer, Ulla.Britt
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Muscle strength training, gait performance and physiotherapy after stroke2008Inngår i: Minerva Medica, ISSN 0026-4806, E-ISSN 1827-1669, Vol. 99, nr 4, s. 353-68Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hemiparesis after stroke, with muscle weakness and reduced gait performance, is a leading cause of long-term disability. To improve lower limb muscle strength and mobility post stroke, there is a need for effective training METHODS: This review summarises the effects of lower limb progressive resistance training ([PRT]; loads of 70% or more of the maximum strength) on muscle strength, muscle tone, gait performance and perceived participation after stroke. PRT is a safe and effective way to improve muscle strength post stroke, without negative effects on muscle tone. Furthermore, improvements in muscle strength positively influence gait performance and perceived participation. Current recommendations for stroke rehabilitation include strength training, which can also be an effective form of fitness training for subjects with minor weakness. Despite its proven effectiveness, further studies are needed to find the most appropriate time to start PRT post-stroke, to identify those stroke individuals that can benefit most from PRT and how to combined PRT with other physiotherapeutic stroke interventions

  • 108. Lexell, Jan
    et al.
    Flansbjer, Ulla-Britt
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Downham, David
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Knee muscle strength, gait performance, and perceived participation after stroke2006Inngår i: Archives of Physical Medicine and Rehabilitation, ISSN 0003-9993, E-ISSN 1532-821X, Vol. 87, nr 7, s. 974-80Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: To assess the relation between knee muscle strength, gait performance, and perceived participation in subjects with chronic mild to moderate poststroke hemiparesis. DESIGN: Descriptive analysis of convenience sample. SETTING: University hospital. PARTICIPANTS: Fifty men and women (mean age, 58+/-6.4y) 6 to 46 months poststroke. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Isokinetic concentric knee extension and flexion strength was measured at 60 degrees /s. Gait performance was assessed by Timed Up & Go, comfortable and fast gait speed, stair climbing ascend and descend, and 6-minute walk test. Perceived participation was assessed with the Stroke Impact Scale. RESULTS: There was a significant correlation (P < .01) between knee muscle strength and gait performance for the paretic but not for the nonparetic lower limb. Strength for the paretic limb explained 34% to 50% of the variance in gait performance; the addition of strength for the nonparetic limb explained at most a further 11% of the variance in gait performance. There was a significant correlation (P < .01) between gait performance and perceived participation; gait performance explained 28% to 40% of the variance in perceived participation. CONCLUSIONS: Knee muscle strength is a moderate to strong predictor of walking ability in individuals with chronic mild to moderate poststroke hemiparesis. Walking ability influences perceived participation, but the strengths of the relations indicate that other factors are also important

  • 109. Lexell, Jan
    et al.
    Flansbjer, Ulla-Britt
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Holmbäck, Anna Maria
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Downham, David
    Department of Rehabilitation, Lund University Hospital, Sweden.
    What change in isokinetic knee muscle strength can be detected in men and women with hemiparesis after stroke?2005Inngår i: Clinical Rehabilitation, ISSN 0269-2155, E-ISSN 1477-0873, Vol. 19, nr 5, s. 514-22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: To assess the intra-rater (between occasions) test-retest reliability of isokinetic knee muscle strength measurements in subjects with chronic poststroke hemiparesis and to define limits for the smallest change that indicates real (clinical) improvements for stroke patients. SUBJECTS: Fifty men and women (mean age 58 +/- 6.4 years) 6-46 months post stroke, able to walk at least 300 m with or without a unilateral assistive device. METHODS: Maximal concentric knee extension and flexion contractions at 60 degrees/s and 120 degrees/s, and maximal eccentric knee extension contractions at 60 degrees/s, with the paretic and nonparetic limbs, were performed seven days apart using a Biodex dynamometer. MEASURES: Reliability of the maximum peak torque measurements was evaluated with the intraclass correlation coefficient (ICC(2,1)), the Bland and Altman analyses, the standard error of measurement (SEM and SEM%) and the smallest real difference (SRD and SRD%). RESULTS: Test-retest agreements were high (ICC(2,1) 0.89-0.96) with no discernible systematic differences between limbs, angular velocities and modes. The SEM%, representing the smallest change that indicates a real (clinical) improvement for a group of subjects, was relatively small (8-20%). The SRD%, representing the smallest change that indicates a real improvement for a single subject ranged from 26% to 33% for concentric knee extension, from 39% to 55% for concentric knee flexion, and from 22% to 25% for eccentric knee extension. CONCLUSION: Isokinetic knee muscle strength can be reliably measured and used to detect real improvements following an intervention for single subjects as well as for groups of subjects with chronic mild to moderate hemiparesis after stroke.

  • 110. Lexell, Jan
    et al.
    Flansbjer, Ulla-Britt
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Holmbäck, Anna Maria
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Downham, David
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Patten, Carolynn
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Reliability of gait performance tests in men and women with hemiparesis after stroke.2005Inngår i: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 37, nr 2, s. 75-82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: To assess the reliability of 6 gait performance tests in individuals with chronic mild to moderate post-stroke hemiparesis. Design: An intra-rater (between occasions) test-retest reliability study. Subjects: Fifty men and women (mean age 58+/-6.4 years) 6-46 months post-stroke. METHODS: The Timed "Up & Go" test, the Comfortable and the Fast Gait Speed tests, the Stair Climbing ascend and descend tests and the 6-Minute Walk test were assessed 7 days apart. Reliability was evaluated with the intraclass correlation coefficient (ICC(2,1)), the Bland & Altman analysis, the standard error of measurement (SEM and SEM%) and the smallest real difference (SRD and SRD%). RESULTS: Test-retest agreements were high (ICC(2,1) 0.94-0.99) with no discernible systematic differences between the tests. The standard error of measurement (SEM%), representing the smallest change that indicates a real (clinical) improvement for a group of individuals, was small (< 9%). The smallest real difference (SRD%), representing the smallest change that indicates a real (clinical) improvement for a single individual, was also small (13-23%). CONCLUSION: These commonly used gait performance tests are highly reliable and can be recommended to evaluate improvements in various aspects of gait performance in individuals with chronic mild to moderate hemiparesis after stroke

  • 111. Lexell, Jan
    et al.
    Glenn, Mel B
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Ginseng2003Inngår i: The journal of head trauma rehabilitation, ISSN 0885-9701, E-ISSN 1550-509X, Vol. 18, nr 2, s. 196-200Artikkel i tidsskrift (Fagfellevurdert)
  • 112. Lexell, Jan
    et al.
    Henriksson-Larsén, K.
    Department of Neurology, University of Umeå.
    Sjöström, Michael
    Department of Neurology, University of Umeå.
    Distribution of different fibre types in human skeletal muscles: 2. A study of cross-sections of whole m. vastus lateralis1983Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 117, nr 1, s. 115-22Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to determine the total number of fibres and the extent to which the relative occurrence of different fibre types varies within m. vastus lateralis, 15 micrometers thick cross-sections of whole muscles were prepared. The total number of type 1 and type 2 fibres was determined in every 48th square millimetre of the section, and the results thus obtained were analysed using a computer program allowing an assessment of bivariate data in the form of contour plots. The total number of fibres varied both in proximal to distal direction in the same muscle and between individuals. No obvious correlation existed between the mean fibre area and the muscle cross-sectional area. The proportion of type 1 fibres in the whole muscle varied between individuals (from 44% to 57%) with a mean value for all five of 52%. The distribution of different fibre types varied within the muscle, mainly as a function of depth, with a predominance to type 2 fibres at the surface and type 1 fibres in deeper regions of the muscle. Thus, the fibre type distribution in m. vastus lateralis is not random. This must be taken into consideration when data on fibre type composition are compared with functional variables

  • 113. Lexell, Jan
    et al.
    Henriksson-Larsén, K.
    Department of Neurology, Umeå university.
    Wnblad, B.
    Department of Neurology, Umeå university.
    Sjöström, Michael
    Department of Neurology, Umeå university.
    Distribution of different fiber types in human skeletal muscles: effects of aging studied in whole muscle cross sections1983Inngår i: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 6, nr 8, s. 588-95Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effects of aging on the total number and size of fibers, and the proportion and distribution of type 1 (slow twitch) and type 2 (fast twitch) fibers were studied in cross sections (15 mu thick) of autopsied whole m. vastus lateralis from two age groups. Each group consisted of six, previously physically healthy males (mean age 72 +/- 1 years and 30 +/- 6 years, respectively). The size of the muscles of the older individuals was 18% smaller (P less than 0.01) and the total number of fibers was 25% lower (P less than 0.01) than those of the young individuals (mean number 364,000 +/- 50,000 vs 478,000 +/- 56,000). There was, however, no significant difference in the mean fiber size (indirectly determined) or the proportion of the two fiber types, though a preferential reduction in type 2 fiber number in the aged individuals was seen. The relative occurrence of the fiber types at various depths in the aged muscles was found to be more even than in muscles from the young individuals. The results suggest that the aging atrophy in m. vastus lateralis, at least up to the age of 70, is primarily the result of a loss of fibers.

  • 114. Lexell, Jan
    et al.
    Holmbäck, Anna Maria
    Department of Physical Therapy, Lund University.
    Porter, Michelle M
    Department of Physical Therapy, Lund University.
    Andersen, Jesper L
    Department of Physical Therapy, Lund University.
    Structure and function of the ankle dorsiflexor muscles in young and moderately active men and women2003Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 95, nr 6, s. 2416-24Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim was to investigate determinants of ankle dorsiflexor muscle (DF) strength and size in moderately active young men and women (n = 30; age 20-31 yr). Concentric (Con) and eccentric (Ecc) strength were measured isokinetically. Magnetic resonance imaging was used to determine the muscle cross-sectional area (CSA). Multiple biopsies were obtained from the tibialis anterior muscle to determine total numbers, areas (Area I and II) and proportions (Prop I and II) of type I and II fibers, respectively, and relative contents of myosin heavy chain (MHC) isoforms MHC1, MHC2a, and MHC2x. Women had lower Con and Ecc strength (24 and 27%; P < 0.01), smaller CSA (19%; P < 0.001), lower Ecc DF specific strength (strength/CSA) (10%; P < 0.01), and smaller Area I and Area II (21 and 31%; P < 0.01) than men. Prop I, MHC1, estimated total number of fibers, and Con DF specific strength were similar for both sexes. Con DF strength was up to 72% determined by CSA and Prop I, and Ecc DF strength was up to 81% determined by CSA, Prop I, and sex; variables other than CSA explained at most 9%. Body weight and fiber areas explained >50% of the variation in CSA. In conclusion, CSA was the predominant determinant of DF strength, CSA was to a great extent determined by the body weight and the sizes of muscle fibers, and sex differences in Ecc specific strength require further study.

  • 115. Lexell, Jan
    et al.
    Holmbäck, Anna-Maria
    Department of Physical Therapy, Lund University.
    Askaner, Krister
    Department of Physical Therapy, Lund University.
    Holtas, Stig
    Department of Physical Therapy, Lund University.
    Downham, David
    Department of Physical Therapy, Lund University.
    Assessment of contractile and noncontractile components in human skeletal muscle by magnetic resonance imaging2002Inngår i: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 25, nr 2, s. 251-258Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A magnetic resonance imaging (MRI) technique for the assessment of contractile and noncontractile components of human skeletal muscle is described, and the inter-rater and intra-rater test-retest reliability for repeated measurements from the same MR image are examined. Twenty cross-sectional MR images from the right lower leg were obtained from 30 healthy young men and women (mean age 24.1 years, SD 3.3). The anatomical cross-sectional area (aCSA; cm2), the cross-sectional area of noncontractile components (Noncon; cm2), the contractile cross-sectional area (cCSA = aCSA minus Noncon; cm2), and the relative amount of Noncon (%), of the ankle dorsiflexor muscle compartment were determined for each slice using a computer-based image analysis system. Reliability for repeated measurements of the slice with the largest aCSA for the 30 subjects was analyzed by two raters on two different occasions. Inter-rater reliability on both occasions, assessed by the intraclass correlation coefficient (ICC), was excellent for cCSA (ICC3.1 = 0.99) and Noncon (ICC(3.1) > 0.82). Intra-rater (between occasions) reliability was excellent for the two raters for measurements of cCSA (ICC1.1 = 0.99) and Noncon (ICC1.1 > 0.94). Bland and Altman analyses did not identify any clinically relevant bias in the measurements. Method errors were acceptable: within subjects coefficients of variation (CV) was less than 1.8% for cCSA and less than 16.3% for Noncon. It is concluded that repeated measurements of contractile and noncontractile components of the ankle dorsiflexor muscle compartment, obtained from the same MR image, are highly reliable

  • 116. Lexell, Jan
    et al.
    Holmbäck, Anna-Maria
    Department of Physical Therapy, Lund University.
    Downham, David
    Department of Mathematical Sciences, University of Liverpool.
    Porter, Michell M
    Faculty of Physical Education and Recreation Studies, University of Manitoba, Winnipeg, Manitoba.
    Ankle dorsiflexor muscle performance in healthy young men and women: reliability of eccentric peak torque and work measurements2001Inngår i: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 33, nr 2, s. 90-96Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aims of this study were: (i) to assess the test-retest intrarater reliability of eccentric ankle dorsiflexor muscle performance in young healthy men and women using the Biodex dynamometer; and (ii) to examine different statistical indices for the interpretation of reliability. Thirty men and women (age 22.5 +/- 2.5 years, mean +/- S.D.) performed three maximal eccentric contractions at 30 degrees/second and 90 degrees/second, with 7-10 days between test sessions. Reliability was evaluated with three intraclass correlation coefficients (ICC1,1, ICC2,1 and ICC3,1), and was excellent for peak torque (ICC 0.90-0.96) and good to excellent for work (ICC 0.69-0.83), with no discernible differences among the three ICCs. Method errors, assessed by the standard error of the measurement (S.E.M.) and S.E.M.%, were low. The Bland & Altman graphs and analyses indicated no significant systematic bias in the data. In conclusion, measurements of eccentric ankle dorsiflexor muscle performance in young healthy individuals using the Biodex are highly reliable.

  • 117. Lexell, Jan
    et al.
    Holmbäck, Anna-Maria
    Department of Physical Therapy, Lund University.
    Downham, David
    Department of Physical Therapy, Lund University.
    Porter, Michelle M
    Department of Physical Therapy, Lund University.
    Reliability of isokinetic ankle dorsiflexor strength measurements in healthy young men and women1999Inngår i: Scandinavian Journal of Rehabilitation Medicine, ISSN 0036-5505, E-ISSN 1940-2228, Vol. 31, nr 4, s. 229-39Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purposes of this study were: (i) to determine the test-retest reliability of isokinetic ankle dorsiflexor strength measurements in young healthy adults using the Biodex dynamometer, and (ii) to examine several statistical measures for the interpretation of reliability. Thirty men and women (mean age 23 +/- 3 years) performed three maximal concentric contractions at 30 degrees/s, 60 degrees/s, 90 degrees/s, 120 degrees/s and 150 degrees/s. Reliability of peak torque, work and torque at a specific time were assessed by calculating the intraclass correlation coefficient (ICC 2,1), Pearson product moment correlation coefficient (r), standard error of the measurement (SEM), method error (ME) and coefficient of variation (CV), and by plotting the differences between observations against their means. Isokinetic tests of ankle dorsiflexor strength in healthy young adults using the Biodex dynamometer were highly reliable (ICC 0.61-0.93). It is recommended that test-retest reliability analyses include the ICC and assessments of measurement errors (SEM, ME or CV), as well as graphs to indicate any systematic variations in the data.

  • 118. Lexell, Jan
    et al.
    Jacobsson, Lars
    Traumatiska hjärnskador2011Inngår i: Kognitiv medicin, Stockholm: Norstedts Förlag, 2011, s. 160-271Kapittel i bok, del av antologi (Fagfellevurdert)
  • 119. Lexell, Jan
    et al.
    Jarvis, JC
    Department of Neurology, University of Umeå.
    Currie, J
    Department of Neurology, University of Umeå.
    Downham, David
    Department of Neurology, University of Umeå.
    Salmons, S
    Department of Neurology, University of Umeå.
    Fibre type composition of rabbit tibialis anterior and extensor digitorum longus muscles1994Inngår i: Journal of Anatomy, ISSN 0021-8782, E-ISSN 1469-7580, Vol. 185, nr Pt 1, s. 95-101Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Rabbit tibialis anterior (TA) and extensor digitorum longus (EDL) muscles are used extensively in studies of stimulation-induced fibre type transformation, but the proportions and sizes of the 2 main fibre types, and the way in which they are distributed within the muscles, have never been described in any detail. In this study, transverse sections were processed by enzyme histochemical and immunohistochemical techniques and assessed morphometrically. The data were analysed by multivariate methods. In both TA and EDL muscles, the proportion of type 1 fibres varied significantly, and to a similar extent, within a cross-section, from lateral to medial and from superficial to deep parts. The fibre density, an indirect estimate of the mean muscle fibre area, also varied significantly, but not systematically, within a cross-section. For the EDL muscle, the proportion of type 1 fibres was consistently higher in the distal than in the proximal part of the muscle. The proportion of type 1 fibres was also significantly higher in the EDL than in the TA muscle for each of the 6 rabbits. There was no systematic variation between muscles from left and right limbs. The type proportions and fibre densities for both TA and EDL muscles differed significantly between individual rabbits, but not between sexes. The study provides a database that has hitherto been lacking on normal fibre type composition and its variation within and between these experimentally important muscles.

  • 120. Lexell, Jan
    et al.
    Jarvis, Jonathan
    Department of Human Anatomy and Cell Biology, University of Liverpool.
    Downham, David
    Department of Statistics & Computational Mathematics, University of Liverpool.
    Salmons, Stanley
    Department of Human Anatomy and Cell Biology, University of Liverpool.
    Quantitative morphology of stimulation-induced damage in rabbit fast-twitch skeletal muscles1992Inngår i: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 269, nr 2, s. 195-204Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to examine the contention that stimulation-induced damage, resulting in degeneration with subsequent regeneration, plays a major role in the transformation of fibre type brought about by chronic electrical stimulation. Data from histological and histochemical sections of 9-day-stimulated rabbit fast-twitch muscles were analysed with multivariate statistical techniques. Fibre degeneration and regeneration varied non-systematically between sample areas at any given cross-sectional level. In the extensor digitorum longus muscle, but not in the tibialis anterior, there was more degeneration in proximal than in distal portions of the muscle. The extensor digitorum longus muscle consistently showed more degeneration than the tibialis anterior muscle. Degeneration was less extensive for an intermittent pattern of stimulation that delivered half the aggregate number of impulses of continuous stimulation. Degeneration and regeneration varied markedly between individual rabbits in each of the groups. Sections that revealed the most degeneration and regeneration also had more fibres that reacted positively with an anti-neonatal antibody. Rigorous analysis of different sources of variation has helped to explain apparent conflicts in the literature. The incidence of muscle fibre damage in the stimulated tibialis anterior muscle is low, showing that the contribution of degenerative-regenerative phenomena to fibre type conversion in this muscle is insignificant.

  • 121. Lexell, Jan
    et al.
    Jarvis, Jonathan
    Department of Human Anatomy and Cell Biology, University of Liverpool.
    Downham, David
    Department of Human Anatomy and Cell Biology, University of Liverpool.
    Salmons, Stanley
    Department of Human Anatomy and Cell Biology, University of Liverpool.
    Stimulation-induced damage in rabbit fast-twitch skeletal muscles: a quantitative morphological study of the influence of pattern and1993Inngår i: Cell and Tissue Research, ISSN 0302-766X, E-ISSN 1432-0878, Vol. 273, nr 2, s. 57-62Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this study was to determine whether muscle fibre degeneration brought about by chronic low-frequency electrical stimulation was related to the pattern and frequency of stimulation. Rabbit fast-twitch muscles, tibialis anterior and extensor digitorum longus, were stimulated for 9 days with pulse trains ranging in frequency from 1.25 Hz to 10 Hz. Histological data from these muscles were analysed with multivariate statistical techniques. At the lower stimulation frequencies there was a significantly lower incidence of degenerating muscle fibres. Fibres that reacted positively with an antineonatal antibody were most numerous in the sections that revealed the most degeneration. The dependence on frequency was generally similar for the two muscles, but the extensor digitorum longus muscles showed more degeneration than the tibialis anterior at every frequency. Muscles subjected to 10 Hz intermittent stimulation showed significantly less degeneration than muscles stimulated with 5 Hz continuously, although the aggregate number of impulses delivered was the same. The incidence of degeneration in the extensor digitorum longus muscles stimulated at 1.25 Hz was indistinguishable from that in control, unstimulated muscles; for the tibialis anterior muscles, this was also true for stimulation at 2.5 Hz. We conclude that damage is not an inevitable consequence of electrical stimulation. The influence of pattern and frequency on damage should be taken into account when devising neuromuscular stimulation regimes for clinical use

  • 122. Lexell, Jan
    et al.
    Jaworowski, A
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Porter, Michele M
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Holmbäck, Anna-Maria
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Downham, David
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Enzyme activities in the tibialis anterior muscle of young moderately active men and women: Relationship with body composition, muscle cross-sectional area and fibre type composition2002Inngår i: Acta Physiologica Scandinavica, ISSN 0001-6772, E-ISSN 1365-201X, Vol. 176, nr 3, s. 215-25Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aims of this study were (i) to assess the differences between men and women in maximal activities of selected enzymes of aerobic and anaerobic pathways involved in skeletal muscle energy production, and (ii) to assess the relationships between maximal enzyme activities, body composition, muscle cross-sectional area (CSA) and fibre type composition. Muscle biopsies were obtained from the tibialis anterior (TA) muscle of 15 men and 15 women (age 20-31 years) with comparable physical activity levels. The muscle CSA was determined by magnetic resonance imaging (MRI). Maximal activities of lactate dehydrogenase (LDH), phosphofructokinase (PFK), beta-hydroxyacyl-coenzyme A dehydrogenase (HAD), succinate dehydrogenase (SDH) and citrate synthase (CS), were assayed spectrophotometrically. The proportion, mean area and relative area (proportion x area) of type 1 and type 2 fibres were determined from muscle biopsies prepared for enzyme histochemistry [myofibrillar adenosine triphosphatase (mATPase)]. The men were significantly taller (+6.6%; P < 0.001) and heavier (+19.1%; P < 0.001), had significantly larger muscle CSA (+19.0%; P < 0.001) and significantly larger areas and relative areas of both type 1 and type 2 fibres (+20.5-31.4%; P = 0.007 to P < 0.001). The men had significantly higher maximal enzyme activities than women for LDH (+27.6%; P = 0.007) and PFK (+25.5%; P = 0.003). There were no significant differences between the men and the women in the activities of HAD (+3.6%; ns), CS (+21.1%; P = 0.084) and SDH (+7.6%; ns). There were significant relationships between height and LDH (r = 0.41; P = 0.023), height and PFK (r = 0.41; P = 0.025), weight and LDH (r = 0.45; P = 0.013), and weight and PFK (r = 0.39; P = 0.032). The relationships were significant between the muscle CSA and the activities of LDH (r = 0.61; P < 0.001) and PFK (r = 0.56; P = 0.001), and between the relative area of type 2 fibres and the activities of LDH (r = 0.49; P = 0.006) and PFK (r = 0.42; P = 0.023). There were no significant relationships between HAD, CS and SDH, and height, weight, muscle CSA and fibre type composition, respectively. These data indicate that the higher maximal activities of LDH and PFK in men are related to the height, weight, muscle CSA and the relative area of type 2 fibres, which are all significantly larger in men than women.

  • 123.
    Lexell, Jan
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering. Department of Health Sciences, Lund University, Lund, Sweden. Department of Neuroscience, Rehabilitation Medicine, Uppsala University, Uppsala, Sweden. Department of Neurology and Rehabilitation Medicine, Skane University Hospital, Lund, Sweden.
    Jonasson, Stina B.
    Department of Health Sciences, Lund University, Lund, Sweden. Department of Neurology and Rehabilitation Medicine, Skane University Hospital, Lund, Sweden.
    Brogårdh, Christina
    Department of Health Sciences, Lund University, Lund, Sweden. Department of Neurology and Rehabilitation Medicine, Skane University Hospital, Lund, Sweden.
    Psychometric Properties of Three Fatigue Rating Scales in Individuals With Late Effects of Polio2018Inngår i: Annals of Rehabilitation Medicine, ISSN 2234-0645, Vol. 42, nr 5, s. 702-712Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective

    To evaluate the psychometric properties of the Fatigue Severity Scale (FSS), the Fatigue Impact Scale (FIS), and the Multidimensional Fatigue Inventory (MFI-20) in persons with late effects of polio (LEoP). More specifically, we explored the data completeness, scaling assumptions, targeting, reliability, and convergent validity.

    Methods

    A postal survey including FSS, FIS, and MFI-20 was administered to 77 persons with LEoP. Responders received a second survey after 3 weeks to enable test-retest reliability analyses.

    Results

    Sixty-one persons (mean age, 68 years; 54% women) responded to the survey (response rate 79%). Data quality of the rating scales was high (with 0%–0.5% missing item responses), the corrected item-total correlations exceeded 0.4 and the scales showed very little floor or ceiling effects (0%–6.6%). All scales had an acceptable reliability (Cronbach’s α ≥0.95) and test-retest reliability (intraclass correlation coefficient, ≥0.80). The standard error of measurement and the smallest detectable difference were 7%–10% and 20%–28% of the possible scoring range. All three scales were highly correlated (Spearman’s correlation coefficient rs=0.79–0.80; p<0.001).

    Conclusion

    The FSS, FIS, and MFI-20 exhibit sound psychometric properties in terms of data completeness, scaling assumptions, targeting, reliability, and convergent validity, suggesting that these three rating scales can be used to assess fatigue in persons with LEoP. As FSS has fewer items and therefore is less time consuming it may be the preferred scale. However, the choice of scale depends on the research question and the study design.

  • 124. Lexell, Jan
    et al.
    Kadi, Fawzi
    Department of Physical Education and Health, Örebro University.
    Charifi, Nadia
    Department of Physical Education and Health, Örebro University.
    Denis, Christian
    Department of Physical Education and Health, Örebro University.
    Satellite cells and myonuclei in young and elderly women and men2004Inngår i: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 29, nr 1, s. 120-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The overall aim of this study was to assess the effects of aging on the satellite cell population. Muscle biopsies were taken from the tibialis anterior muscle of healthy, moderately active young (age range, 20-32 years; n = 31) and elderly (age range, 70-83 years; n = 27) women and men with comparable physical activity pattern. Satellite cells and myonuclei were visualized using a monoclonal antibody against neural cell adhesion molecule and counterstained with Mayer's hematoxylin. An average of 211 (range, 192-241) muscle fibers were examined for each individual. Compared with the young women and men, the elderly subjects had a significantly lower (P < 0.011) number of satellite cells per muscle fiber but a significantly higher (P < 0.004) number of myonuclei per muscle fiber. The number of satellite cells relative to the total number of nuclei [satellite cells/(myonuclei + satellite cells)] was significantly lower in the elderly than in the young women and men. These results imply that a reduction in the satellite cell population occurs as a result of increasing age in healthy men and women

  • 125. Lexell, Jan
    et al.
    Kadi, Fawzi
    Department of Physical Education and Health, Örebro University.
    Charifi, Nadia
    Department of Physical Education and Health, Örebro University.
    Denis, Christian
    Department of Physical Education and Health, Örebro University.
    Andersen, Jesper L
    Department of Physical Education and Health, Örebro University.
    Schjerling, Peter
    Department of Physical Education and Health, Örebro University.
    Olsen, Steen
    Department of Physical Education and Health, Örebro University.
    Kjaer, Michael
    Department of Physical Education and Health, Örebro University.
    The behaviour of satellite cells in response to exercise: what have we learned from human studies?2005Inngår i: Pflügers Archiv: European Journal of Physiology, ISSN 0031-6768, E-ISSN 1432-2013, Vol. 451, nr 2, s. 319-27Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Understanding the complex role played by satellite cells in the adaptive response to exercise in human skeletal muscle has just begun. The development of reliable markers for the identification of satellite cell status (quiescence/activation/proliferation) is an important step towards the understanding of satellite cell behaviour in exercised human muscles. It is hypothesised currently that exercise in humans can induce (1) the activation of satellite cells without proliferation, (2) proliferation and withdrawal from differentiation, (3) proliferation and differentiation to provide myonuclei and (4) proliferation and differentiation to generate new muscle fibres or to repair segmental fibre injuries. In humans, the satellite cell pool can increase as early as 4 days following a single bout of exercise and is maintained at higher level following several weeks of training. Cessation of training is associated with a gradual reduction of the previously enhanced satellite cell pool. In the elderly, training counteracts the normal decline in satellite cell number seen with ageing. When the transcriptional activity of existing myonuclei reaches its maximum, daughter cells generated by satellite cell proliferation are involved in protein synthesis by enhancing the number of nuclear domains. Clearly, delineating the events and the mechanisms behind the activation of satellite cells both under physiological and pathological conditions in human skeletal muscles remains an important challenge.

  • 126.
    Lexell, Jan
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Krylborg, Eva
    Norrbottens Läns Landsting.
    Wallmark, Ingrid
    Norrbottens Läns Landsting.
    Engström, Mats
    Winternet.
    Sellin, Christina Karlenby
    Norrbottens Läns Landsting.
    Forsberg, Håkan
    Norrbottens Läns Landsting.
    Rönnblom, Anders
    Norrbottens Läns Landsting.
    Andersson, Susanne
    Norrbottens Läns Landsting.
    Lampinen, Josefine
    Norrbottens Läns Landsting.
    Östlin, Annica
    Norrbottens Läns Landsting.
    Rehabilitering vid dystrophia myotonica: Framgångsrikt försök med interdisciplinärt team i Norrbotten1999Inngår i: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 96, nr 40, s. 4337-40Artikkel i tidsskrift (Fagfellevurdert)
  • 127. Lexell, Jan
    et al.
    Lexell, Eva Månsson
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Iwarsson, S
    Department of Rehabilitation, Lund University Hospital, Sweden.
    The complexity of daily occupations in multiple sclerosis2006Inngår i: Scandinavian Journal of Occupational Therapy, ISSN 1103-8128, E-ISSN 1651-2014, Vol. 13, nr 4, s. 241-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aims of this study were to describe which self-care, productivity, and leisure occupations individuals with multiple sclerosis (MS) perceive as difficult to perform on admission to rehabilitation and the individuals' own perception of the importance of, performance of, and satisfaction with these occupations. Whether the reported self-care, productivity, and leisure occupations were related to sex, age, disease severity, and living arrangements was also investigated. Forty-seven men and women (mean age 49.4 years) were assessed with the Canadian Occupational Performance Measure (COPM) on admission to rehabilitation. The individuals reported 366 occupations (median 8, range 3-15), which were categorized as self-care (51%), productivity (30%), and leisure (19%). Three COPM subcategories--household management (26%), personal care (21%), and functional mobility (20%)--accounted for two-thirds of the reported occupations. All prioritized occupations (n = 238; (median 5, range 2-7) had high ratings for importance and the ratings for performance and satisfaction were generally low. Men reported significantly more occupations related to self-care than women, but no significant difference between the sexes could be found for productivity and leisure. No significant differences between the occupational areas were found when age, disease severity, or/and living arrangements were included in the analysis. In conclusion, individuals with MS perceive difficulties with occupations related to all aspects of daily life. This underscores the need to use assessment tools that capture the complexity of daily occupations.

  • 128. Lexell, Jan
    et al.
    Lindstedt, Marta
    Universitetssjukhuset i Lund.
    Tengvar, Christer
    Universitetssjukhuset i Lund.
    Sörbo, Ann
    Universitetssjukhuset i Lund.
    Farmakologiska möjligheter vid hjärnskadebehandling: rätt läkemedelsval kan optimera rehabiliteringsinsatserna2007Inngår i: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 104, nr 35, s. 2422-2426Artikkel i tidsskrift (Annet vitenskapelig)
  • 129. Lexell, Jan
    et al.
    Lindström, Britta
    Department of Community Medicine and Rehabilitation, Physiotherapy, Umeå University, Umeå, Sweden.
    Karlsson, Stefan J
    Department of Biomedical Engineering and Informatics, University Hospital, Umeå, Sweden.
    Isokinetic torque and surface electromyography during fatiguing muscle contractions in young and older men and women2006Inngår i: Isokinetics and exercise science, ISSN 0959-3020, E-ISSN 1878-5913, Vol. 14, nr 3, s. 225-234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The overall aim was to investigate the fatigue pattern and perceived fatigue during repetitive dynamic contractions in young and older men and women. Sixteen older men and women (mean age 73 ± 3 years) and 22 young men and women (mean age 28 ± 6 years) performed 100 repeated maximum concentric isokinetic knee extension contractions at 90°·s-1 (1.57 rad·s-1). Throughout the 100 contractions, peak torque (PT) and surface electromyography (EMG) signals from the rectus femoris muscle and the vastus lateralis muscle were recorded simultaneously, together with perceived fatigue (CR-10 scale of Borg). The mean frequency of the power spectrum (MNF) and the root mean square of the signal amplitude (RMS) of the EMG were affected by age and with a sex related difference but for PT the difference of the fatigue pattern was most evident between the sexes. In addition, the young men rated the highest fatigue. Based on EMG, PT and ratings of perceived fatigue it was concluded that the old men fatigued most, the old women fatigued least and the young men perceived greatest fatigue.

  • 130.
    Lexell, Jan
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap.
    Lindén, Anita
    Luleå tekniska universitet, Institutionen för hälsovetenskap.
    Lövgren-Engström, Ann-Louice
    Luleå tekniska universitet, Institutionen för hälsovetenskap.
    Larsson-Lund, Maria
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Hälsa och rehabilitering.
    Projektrapport Kognitek: delprojektet i Lund2008Rapport (Annet (populærvitenskap, debatt, mm))
  • 131. Lexell, Jan
    et al.
    Loes, M De
    Institute of Research, Swiss School of Sports, Macolin.
    Friidrottskongressen. Vårmötet i Göteborg 1-3 augusti1995Inngår i: Svensk idrottsmedicin, ISSN 1103-7652, Vol. 14, nr 5, s. 14-20Artikkel i tidsskrift (Annet vitenskapelig)
  • 132. Lexell, Jan
    et al.
    Malec, James F.
    Rehabilitation Hospital of Indiana and Indiana University School of Medicine.
    Jacobsson, Lars J.
    Medical Rehabilitation Section, Department of General Medicine, Kalix Hospitral.
    Mapping the Mayo-Portland Adaptability Inventory to the International Classification of Functioning, Disability and Health2012Inngår i: Journal of Rehabilitation Medicine, ISSN 1650-1977, E-ISSN 1651-2081, Vol. 44, nr 1, s. 65-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Objective: To examine the contents of the Mayo-Portland Adaptability Inventory (MPAI-4) by mapping it to the International Classification of Functioning, Disability and Health (ICF). Methods: Each of the 30 scoreable items in the MPAI-4 was mapped to the most precise ICF categories. Results: All 30 items could be mapped to components and categories in the ICF. A total of 88 meaningful concepts were identified. There were, on average, 2.9 meaningful concepts per item, and 65% of all concepts could be mapped. Items in the Ability and Adjustment subscales mapped to categories in both the Body Functions and Activity/Participation components of the ICF, whereas all except 1 in the Participation subscale were to categories in the Activity/Participation component. The items could also be mapped to 34 (13%) of the 258 Environmental Factors in the ICF. Conclusion: This mapping provides better definition through more concrete examples (as listed in the ICF) of the types of body functions, activities, and participation indicators that are represented by the 30 scoreable MPAI-4 items. This may assist users throughout the world in understanding the intent of each item, and support further development and the possibility to report results in the form of an ICF categorical profile, making it universally interpretable

  • 133. Lexell, Jan
    et al.
    Miller, Michael
    Department of Clinical Sciences, Division of Rehabilitation Medicine, Lund university.
    The interpolated twitch technique may be valid and reliable but limited2009Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 107, nr 1, s. 362, 367-368Artikkel i tidsskrift (Annet vitenskapelig)
  • 134. Lexell, Jan
    et al.
    Miller, Michael
    Department of Physical Therapy, Lund University.
    Downham, David
    Department of Physical Therapy, Lund University.
    Effects of superimposed electrical stimulation on perceived discomfort and torque increment size and variability2003Inngår i: Muscle and Nerve, ISSN 0148-639X, E-ISSN 1097-4598, Vol. 27, nr 1, s. 90-8Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Superimposed electrical stimulation techniques can be used to detect central activation failure (CAF), that is, incomplete central nervous system recruitment or suboptimal activation of motor units. The purpose of this study was to evaluate the effects of two stimulation parameters on perceived discomfort and torque increment size and variability. Discomfort was evaluated using a visual analog scale (0-100 mm) for pain. The rectus femoris muscle of the dominant leg of 24 young healthy men was stimulated during submaximal (80% maximal) voluntary contractions. The size and variability of torque increments and perceived discomfort were assessed following stimulation with: (1) pulse trains (100 HZ, 150 V, 0.2-ms pulse duration) of different lengths (50 ms and 100 ms); and (2) pulse trains (100 HZ, 100 ms, 150 V) with different pulse durations (0.2 ms and 0.1 ms). Pulse trains of 100 ms generated larger torque increments and produced less variability, but caused more discomfort than pulse trains of 50 ms. Average discomfort ratings for pulse trains of 100 ms were 43.1 mm, and of 50 ms were 53.2 mm. There was no difference in torque increment size or in variability between pulse trains with pulse durations of 0.1 ms and 0.2 ms, whereas discomfort was less for the shorter pulse durations; average discomfort ratings were 53.1 mm and 58.1 mm for pulse durations of 0.1 ms and 0.2 ms, respectively. Thus, the appropriate selection of stimulation parameters can reduce discomfort but maintain the ability to detect CAF.

  • 135. Lexell, Jan
    et al.
    Miller, Michael
    Department of Health Sciences, Lund University.
    Flansbjer, Ulla-Britt
    Department of Health Sciences, Lund University.
    Downham, David
    Department of Health Sciences, Lund University.
    Superimposed electrical stimulation: assessment of voluntary activation and perceived discomfort in healthy, moderately active older and younger women and men2006Inngår i: American Journal of Physical Medicine & Rehabilitation, ISSN 0894-9115, E-ISSN 1537-7385, Vol. 85, nr 12, s. 945-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    OBJECTIVE: An inability of the nervous system to fully activate the muscle is one factor that can contribute to age-related muscle weakness. Superimposed electrical stimulation can be used to determine voluntary muscle activation (VA). The aim of this study was to assess VA of the quadriceps muscle in healthy older and younger subjects. DESIGN: Electrical stimulation causes moderate discomfort in younger subjects, but no study has assessed discomfort in older subjects. The quadriceps muscle in 20 moderately active older subjects (mean age, 75 yrs) and 12 younger subjects (mean age, 25 yrs) was stimulated during two maximal voluntary contractions using a 100-Hz pulse train. A visual analog scale for pain (VAS-pain) was used to evaluate discomfort. RESULTS: Ability to activate the quadriceps muscle was generally very high, and there was no significant difference between the older (mean, 0.96) and younger (mean, 0.98) subjects. Discomfort did not differ between the older (mean VAS-pain score, 41 mm) and younger (mean VAS-pain score, 37 mm) subjects. CONCLUSIONS: Our results indicate that healthy, moderately active older subjects have the ability to almost complete VA of the quadriceps muscle and that discomfort during electrical stimulation is generally moderate.

  • 136. Lexell, Jan
    et al.
    Miller, Michael
    Department of Health Sciences, Lund University.
    Holmbäck, Anna-Maria
    Department of Health Sciences, Lund University.
    Downham, David
    Department of Health Sciences, Lund University.
    Voluntary activation and central activation failure in the knee extensors in young women and men2006Inngår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 16, nr 4, s. 274-81Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quadriceps muscle weakness is common after knee injuries. This weakness is caused, in part, by reduced voluntary activation (VA) because of central activation failure (CAF). Superimposed electrical stimulation techniques are used to assess VA and to detect CAF. The aim of this study was to assess VA during knee extension in young healthy women and men, and to evaluate subjective discomfort from the electrical stimulation. The quadriceps muscle in six young healthy women (mean age 22 years) and six young healthy men (mean age 29 years) was stimulated during maximal voluntary contractions using a 100 Hz pulse train. Data were collected from two test sessions separated by 6-8 days and each session comprised of two trials. A visual analog scale for pain (VAS-pain) was used to evaluate subjective discomfort. Overall, young healthy, moderately active men and women did have the ability to fully activate their knee extensors isometrically, but they did not achieve full activation on every trial. In those trials where a CAF was detected, the degree was small (mean less than 2%), and did not vary between the two test sessions. Subjective discomfort was generally moderate and tolerable (mean VAS-pain score 35 mm). These results will assist the clinical assessment of muscle weakness following a knee injury and facilitate the design and evaluation of appropriate rehabilitation interventions.

  • 137. Lexell, Jan
    et al.
    Månsson, Eva
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Performance of activities of daily living in multiple sclerosis2004Inngår i: Disability and Rehabilitation, ISSN 0963-8288, E-ISSN 1464-5165, Vol. 26, nr 10, s. 576-85Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    PURPOSE: To assess the performance of activities of daily living (ADL) in individuals with moderate to severe multiple sclerosis (MS). METHOD: A total of 12 men and 32 women with MS (Expanded Disability Status Scale, EDSS, 6.0-8.5) were studied. The performance of personal ADL (P-ADL) and instrumental ADL (I-ADL) was assessed with the Functional Independence Measure (FIM) and the Assessment of Motor and Process Skills (AMPS). RESULTS: Twenty-four of the 44 individuals were rated dependent in P-ADL by the FIM motor score, mainly due to limitations in some areas of self-care and in transfers and locomotion. Only three individuals were rated dependent by the FIM cognitive score, indicating no or little cognitive disability. Two thirds of the individuals who were rated independent/modified independent in P-ADL by the FIM were rated dependent in I-ADL by the AMPS. Only the FIM motor score was significantly related to the EDSS score, indicating that ADL performance and disease severity is weakly related. CONCLUSIONS: Moderate to severe MS reduces the ability to perform both P-ADL and I-ADL. An individual with MS can be independent in P-ADL but still unable to perform I-ADL satisfactorily. Assessments of both P-ADL and I-ADL are advocated to evaluate ADL performance in order to implement appropriate management strategies for individuals with MS.

  • 138. Lexell, Jan
    et al.
    Nilsson, E
    Multipel skleros - att mäta och utvärdera rehabilitering och behandling1999Inngår i: Svensk rehabilitering, ISSN 1403-4468, nr 3, s. 36-8Artikkel i tidsskrift (Annet vitenskapelig)
  • 139. Lexell, Jan
    et al.
    Nilsson, E
    Multipel skleros - multidisciplinärt teamarbete1999Inngår i: Svensk rehabilitering, ISSN 1403-4468, Vol. 1, nr 1, s. 12-14Artikkel i tidsskrift (Annet vitenskapelig)
  • 140. Lexell, Jan
    et al.
    Ohlson, U
    Hur påverkas den kvinnliga sexualiteten av ryggmärgsskada?1999Inngår i: Svensk rehabilitering, ISSN 1403-4468, nr 3, s. 18-20Artikkel i tidsskrift (Annet vitenskapelig)
  • 141. Lexell, Jan
    et al.
    Ohlson, U
    Lust och sexuell aktivitet hos kvinnor med ryggmärgsskada1999Inngår i: Svensk rehabilitering, ISSN 1403-4468, Vol. 1, nr 4, s. 44-46Artikkel i tidsskrift (Annet vitenskapelig)
  • 142. Lexell, Jan
    et al.
    Patten, Carolynn
    Rehabilitation R&D Center/153, VA Palo Alto.
    Brown, Heather E
    Rehabilitation R&D Center/153, VA Palo Alto.
    Weakness and strength training in persons with poststroke hemiplegia: Rationale, method, and efficacy2004Inngår i: Journal of rehabilitation research and development, ISSN 0748-7711, E-ISSN 1938-1352, Vol. 41, nr 3 A, s. 293-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several converging lines of contemporary evidence suggest that weakness presents a more serious compromise to movement function in poststroke hemiplegia than spasticity. This review examines the clinical and functional phenomena of weakness in poststroke hemiplegia, currently available evidence identifying physiologic substrates contri-buting to weakness, and reports of early investigations involving high-resistance training targeted at improving strength and the trans fer of strength to improvements in functional capacity. Based on this information, we describe some unsolved problems and indicate some likely lines of development to increase our knowledge regarding how resistance training can be included in effective stroke rehabilitation.

  • 143. Lexell, Jan
    et al.
    Patten, Carolynn
    Rehabilitation Research and Development Center, Department of Veterans.
    Kothari, Dhara
    Rehabilitation Research and Development Center, Department of Veterans.
    Whitney, Jennifer
    Rehabilitation Research and Development Center, Department of Veterans.
    Lum, Peter S
    Rehabilitation Research and Development Center, Department of Veterans.
    Reliability and responsiveness of elbow trajectory tracking in chronic poststroke hemiparesis2003Inngår i: Journal of rehabilitation research and development, ISSN 0748-7711, E-ISSN 1938-1352, Vol. 40, nr 6, s. 487-500Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study established the reliability of a novel upper-limb trajectory-tracking task for assessment of perceptual motor control in hemiparetic adults. Eleven persons with chronic poststroke hemiparesis (mean 58.6 months) and eleven nondisabled control subjects performed an elbow flexion-extension task against a low-resistance isotonic load at three speeds: 25 degrees/s, 45 degrees/s, and 65 degrees/s. Both arms (paretic and nonparetic or dominant and nondominant) were tested during two identical sessions separated by 1 week. Relative reliability (intraclass correlation coefficient [ICC]) ranged from 0.5 to 0.8 and absolute reliability (standard error of measurement [SEM%]) ranged between 19% to 36% across both subject groups. No systematic errors between test sessions were revealed. Smallest real differences (SRDs) were determined to be +/- 2 degrees to 3 degrees in nondisabled, +/- 2 degrees to 5 degrees in nonparetic and +/- 9 degrees in paretic arms. Responsiveness ratios derived with the use of the SRDs ranged between 1.91 to 2.45, indicating that this instrument is sensitive to clinically important change and suitable for demonstrating effects on upper-limb motor performance following clinical intervention.

  • 144. Lexell, Jan
    et al.
    Porter, Michelle M
    Faculty of Physical Education and Recreation Studies, University of Manitoba, Winnipeg, Manitoba.
    Holmbäck, Anna Maria
    Faculty of Physical Education and Recreation Studies, University of Manitoba, Winnipeg, Manitoba.
    Reliability of concentric ankle dorsiflexion fatigue testing2002Inngår i: Canadian Journal of Applied Physiology, ISSN 1066-7814, E-ISSN 1543-2718, Vol. 27, nr 2, s. 116-27Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to determine the reliability of an isokinetic test for ankle dorsiflexion fatigue on a Biodex dynamometer. Young (21 to 32 years), recreationally active men (n = 10) and women (n = 10) performed 50 concentric (60 degrees.s-1) dorsiflexion contractions, on two different occasions. Total work (TW), losses in work (work fatigue; WF), as well as relative losses in peak toruqe, an example being "3-3" which compared the first three to last three repetitions, were measured. The intra-class correlation coefficients (ICC2.1) and coefficients of variation (CV), as well as the Bland-Altman plots and analyses showed that the variables using peak torque and TW were more reliable than WF, with WF having a CV of 11.3% and the best peak torque variable, 3-3, having a CV of 5.6%. In conclusion, ankle dorsiflexion fatigue can be reliably assessed on a Biodex dynamometer

  • 145. Lexell, Jan
    et al.
    Porter, Michelle M
    Faculty of Physical Education and Recreation Studies, University of Manitoba, Winnipeg, Manitoba.
    Stuart, S
    Faculty of Physical Education and Recreation Studies, University of Manitoba, Winnipeg, Manitoba.
    Boij, M
    Department of Rehabilitation, Lund University Hospital, Sweden.
    Capillary supply of the tibialis anterior muscle in young, healthy, and moderately active men and women.2002Inngår i: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 92, nr 4, s. 1451-1457Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tibialis anterior muscle biopsies from moderately active men and women (21-30 yr; n = 30) were examined to determine potential gender differences in capillarization. The fiber type proportions [type I (T1) approximately 73%] were unaffected by gender. The men (M) had significantly (P < 0.001) larger fibers than the women (W), with a greater gender effect for type II (T2) fibers (P < 0.001). The M and W had similar capillary densities (CD approximately 390 capillaries/mm2), but the capillaries-to-fiber ratio (C/F) was higher in the M (M = 2.20 +/- 0.35, W = 1.66 +/- 0.32; P < 0.01). Capillary contacts (CC) were higher in T2 than T1 for the M (P < 0.01), but not W, and M had greater CC (P < 0.001). Both fiber area per capillary (FA/C) and fiber perimeter per capillary (FP/C) indicated that T1 fibers had greater capillarization than T2 fibers (P < 0.001). There were no gender differences in T1 FA/C and T2 FA/C or T1 FP/C, but a gender difference existed for T2 FP/C (M = 60.5 +/- 10.9, W = 70.6 +/- 13.4; P < 0.01). The gender difference for C/F could be explained by fiber size; however, the physiological implications of the difference in T2 FP/C remains to be determined. In conclusion, despite gender differences for fiber size, overall, capillarization was similar between the men and women.

  • 146. Lexell, Jan
    et al.
    Porter, Michelle M
    Faculty of Kinesiology, University of Western Ontario, London.
    Vandervoort, AA
    Faculty of Kinesiology, University of Western Ontario, London.
    Aging of human muscle: structure, function and adaptability1995Inngår i: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 5, nr 3, s. 129-142Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    With increasing age, human skeletal muscles gradually decrease in volume, mainly due to a reduced number of motor units and muscle fibers, and a reduced size of type 2 fibers. As a result, progressive weakening and impaired mobility occur. High-resistance strength training is beneficial, even in the very old, and could possibly reverse some of the detrimental effects of age-related weakness. The importance of exercise for older people affords an excellent opportunity for the medicine community as a major source of information and promotion of physical activity for this rapidly growing segment of the population. In this review, we summarize the current knowledge of the effects of aging on the human neuromuscular system, describe some of the major underlying mechanisms of the aging atrophy and focus on the importance of strength training to improve muscle function in older people.

  • 147. Lexell, Jan
    et al.
    Ratkevicius, A
    Department of Physiology and Biochemistry, Lithuanian Institute of Physical Education, Kaunas.
    Skurvydas, A
    Department of Physiology and Biochemistry, Lithuanian Institute of Physical Education, Kaunas.
    Povilonis, E
    Department of Physiology and Biochemistry, Lithuanian Institute of Physical Education, Kaunas.
    Quistorff, B
    Department of Physiology and Biochemistry, Lithuanian Institute of Physical Education, Kaunas.
    Effects of contraction duration on low-frequency fatigue in voluntary and electrically induced exercise of quadriceps muscle in humans1998Inngår i: European Journal of Applied Physiology and Occupational Physiology, ISSN 0301-5548, E-ISSN 1432-1025, Vol. 77, nr 5, s. 462-468Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aims of this study were to investigate if low-frequency fatigue (LFF) dependent on the duration of repeated muscle contractions and to compare LFF in voluntary and electrically induced exercise. Male subjects performed three 9-min periods of repeated isometric knee extensions at 40% maximal voluntary contraction with contraction plus relaxation periods of 30 plus 60 s, 15 plus 30 s and 5 plus 10 s in protocols 1, 2 and 3, respectively. The same exercise protocols were repeated using feedback-controlled electrical stimulation at 40% maximal tetanic torque. Before and 15 min after each exercise period, knee extension torque at 1, 7, 10, 15, 20, 50 and 100 Hz was assessed. During voluntary exercise, electromyogram root mean square (EMGrms) of the vastus lateralis muscle was evaluated. The 20-Hz torque:100-Hz torque (20:100 Hz torque) ratio was reduced more after electrically induced than after voluntary exercise (P < 0.05). During electrically induced exercise, the decrease in 20:100 Hz torque ratio was gradually (P < 0.05) reduced as the individual contractions shortened. During voluntary exercise, the decrease in 20:100 Hz torque ratio and the increase in EMGrms were greater in protocol 1 (P < 0.01) than in protocols 2 and 3, which did not differ from each other. In conclusion, our results showed that LFF is dependent on the duration of individual muscle contractions during repetitive isometric exercise and that the electrically induced exercise produced a more pronounced LFF compared to voluntary exercise of submaximal intensity. It is suggested that compensatory recruitment of faster-contracting motor units is an additional factor affecting the severity of LFF during voluntary exercise

  • 148. Lexell, Jan
    et al.
    Robertsson, E
    Umeå universitet.
    Stenström, E
    Umeå universitet.
    Effects of strength training in elderly women1992Inngår i: Journal of The American Geriatrics Society, ISSN 0002-8614, E-ISSN 1532-5415, Vol. 40, nr 2, s. 190-191Artikkel i tidsskrift (Fagfellevurdert)
  • 149. Lexell, Jan
    et al.
    Romner, Bertil
    Universitetssjukhuset i Lund, Neurokirurgiska kliniken.
    Tegner, Yelverton
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Idrott och skallskador: riktlinjer för omhändertagande och återgång till träning och tävling2000Inngår i: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 97, nr 43, s. 4848-53Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Head injuries in sports have received increased attention during the past decade. As explained in this article, the most recent guidelines for the management of head injuries in sports adopted by the American Academy of Neurology (AAN) have been adapted for the Swedish sports society. The guidelines include a grading scale of head injuries in sports, a sideline evaluation to aid physicians, coaches and athletes in the acute situation, and a management strategy for safe return to play after a head injury. The use of these guidelines will facilitate appropriate acute and subacute management and thereby prevent repeated head injuries that could lead to potentially catastrophic outcome or long-term cognitive sequelae

  • 150.
    Lexell, Jan
    et al.
    Luleå tekniska universitet, Institutionen för hälsovetenskap.
    Romner, Bertil
    Universitetssjukhuset i Lund, Neurokirurgiska kliniken.
    Tegner, Yelverton
    Luleå tekniska universitet, Institutionen för hälsovetenskap, Medicinsk vetenskap.
    Skallskador hos idrottare: nya svenska rekommendationer2001Inngår i: Svensk idrottsmedicin, ISSN 1103-7652, Vol. 20, nr 3, s. 4-11Artikkel i tidsskrift (Annet vitenskapelig)
1234 101 - 150 of 191
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf