Stig Peter Magnusson

• Bachelor of Science, DMSc
• Bispebjerg Hospital, Copenhagen University

Background This protocol was developed to describe the design of a randomised controlled trial that will examine the clinical efficacy of a 6-week, novel, home-based stretching programme compared with usual care on the effect of symptoms experienced by patients with fibromyalgia. The hypothesis is that the total score of the Fibromyalgia Impact Que...

Injuries to the musculoskeletal system are frequent in elite sports and they are detrimental to athletic performance. This can be due to, for example, (1) overuse disorders of tendon (tendinopathy) that not only lower the training efficiency but also, in many cases, are career‐ending for the athlete due to pain; (2) acute muscle strain injury that...

Knowledge of how to treat chronic tendinopathy has advanced in recent years, but the treatment of early tendinopathy is not well understood. The main purpose of this prospective observational study was to investigate if changes occur in clinical and imaging outcomes over 12 weeks in elite athletes with recent debut of tendinopathy. Sixty‐five elite...

INTRODUCTION Patients with diabetes have an increased risk of developing tendon injuries, which may be due to prolonged weakening of connective tissue caused by metabolic imbalance. We investigated whether the current standard care for type 2 diabetes, which reduces blood sugar and lipid levels, also reduces the risk of tendon injuries. This had no...

Purpose To investigate power Doppler (PD) activity and tendon structure (between the injured and contralateral limb) in patients with unilateral patellar tendinopathy (PT) using ultrasonography (US). Secondly, the aim was to determine the intra‐rater reliability of the PD activity and tendon structure. Methods This study analyzed US baseline data...

Introduction Heavy‐load free‐flow resistance exercise (HL‐FFRE) is a widely used training modality. Recently, low‐load blood‐flow restricted resistance exercise (LL‐BFRRE) has gained attention in both athletic and clinical settings as an alternative when conventional HL‐FFRE is contraindicated or not tolerated. LL‐BFRRE has been shown to result in...

Background Lateral elbow tendinopathy is a disabling tendon overuse injury. It remains unknown if a corticosteroid injection (CSI) or tendon needling (TN) combined with heavy slow resistance (HSR) training is superior to HSR alone in treating lateral elbow tendinopathy. Purpose/Hypothesis The purpose was to investigate the effects of HSR combined...

Persistent muscle weakness, tendon elongation, and incomplete return to preinjury level are frequent sequelae after acute Achilles tendon rupture, and evidence-based knowledge of how to best rehabilitate the injury is largely absent in the literature. The objective of this review is to illuminate and discuss to what extent an Achilles tendon ruptur...

Purpose: To examine acromio-humeral distance (AHD) and shoulder isometric strength for external rotation (ER) and internal rotation (IR) in national elite badminton players. Methods: Seven elite badminton players with asymptomatic shoulders aged 24 ± 4 (mean ± SD) from the Danish national badminton team were investigated. Shoulder AHD, isometric...

Background T2* mapping has proven useful in tendon research and may have the ability to detect subtle changes at an early stage of tendinopathy. Purpose To investigate the difference in T2* between patients with early tendinopathy and healthy controls, and to investigate the relationship between T2* and clinical outcomes, tendon size, and mechanic...

Parkinson’s disease (PD) is a neurodegenerative disease and a multidisciplinary approach to rehabilitation has been suggested as the best clinical practice. However, very few studies have investigated the long-term e�ects of a multidisciplinary rehabilitation approach, particularly regarding whether this can slow the progression of PD. The purpose...

Tendon pathology (tendinopathy) typically occurs in specific regions of a tendon and growth in response to exercise also appears to be more pronounced in specific regions. In a previous study in animals we found evidence of regional differences in tendon turnover, but whether the turnover of human patellar tendon differs in different regions still...

Fibrillin‐1 mutations cause pathological changes in connective tissue that constitute the complex phenotype of Marfan syndrome. In this study, we used fibrillin‐1 hypomorphic and haploinsufficient mice (Fbn1mgr/mgR and Fbn1+/− mice, respectively) to investigate the impact of fibrillin‐1 deficiency alone or in combination with regular physical activ...

Visceral adipose tissue is an immunogenic tissue, which turns detrimental during obesity by activation of proinflammatory macrophages. During aging, chronic inflammation increases proportional to visceral adipose tissue (VAT) mass and associates with escalating morbidity and mortality. Here, we utilize a mouse model to investigate the inflammatory...

This review summarises the treatment of acute muscle injuries. Muscle injuries are frequent traumatic injuries caused by either excessive strain on the muscle tendon unit (strain injury) or a forceful blow to the muscle (contusion). An early start of rehabilitation after acute strain injuries is a key to shortening the time to return to sport. The...

Background: Arm paresis is present in 48% to 77% of acute stroke patients. Complete functional recovery is reported in only 12% to 34%. Although the arm recovery is most pronounced during the first 4 weeks poststroke, few studies examined the effect of upper extremity interventions during this period. Objective: To investigate the effect of elec...

Purpose: Hereditary connective tissue disorders (HCTDs), such as classic Ehlers-Danlos syndrome (cEDS) and Marfan syndrome (MS) share overlapping features like hypermobility and tissue fragility. In clinical practice it remains a challenge to distinguish children and adolescents with HCTD from healthy children. The purpose of this study was to inv...

Aging negatively affects collagen-rich tissue like tendons, but in vivo tendon mechanical properties and the influence of physical activity after the 8thdecade of life remains to be determined. This study aimed to compare in vivo patellar tendon mechanical properties in moderately old (OLD) and very old (VERY OLD) adults, and the effect of short te...

It is largely unknown how much heavy resistance exercise induces an acute increase in systolic blood pressure (SBP), and if such increase can be measured in a reliable manner with non-invasive equipment. To investigate test–retest (day-to-day) reproducibility of acute SBP response during heavy resistance exercise using a non-invasive methodology (N...

Statement of significance: Tendons are connective tissues that connect muscle to bone and carry some of the greatest mechanical loads in the body, which makes them common sites of injury. A tendon is essentially a biological rope formed by thin strands called fibrils made of the protein collagen. Tendon function relies on the strength of these fib...

Background and purpose: Older adults acutely hospitalized for medical illness typically have comorbidity and disability, and inhospital physical inactivity greatly increases the likelihood of developing new disability. Thus, assessment of the patients' mobility status is crucial for planning and carrying out targeted interventions that ensure mobi...

Background and purpose: Patients with hip osteoarthritis have impairments in muscle function (muscle strength and power) and hip range of motion (ROM), and it is commonly believed that effective clinical management of osteoarthritis should address these impairments to reduce pain and disability. Therefore, the purpose of this study was to compare...

Trabecular bone is viscoelastic under dynamic loading. However, it is unclear how tissue viscoelasticity controls viscoelasticity at the apparent-level. In this study, viscoelasticity of cylindrical human trabecular bone samples (n=11, male, age 18-78 years) from 11 proximal femurs were characterized using dynamic and stress-relaxation testing at t...

In this randomized study involving 50 amateur athletes with severe injury to thigh or calf muscles, a return to full activity was more rapid when the rehabilitation program was started 2 days rather than 9 days after injury.

Aims: To assess the live-versus-video, intrarater interday and interrater interday reliability of the test Segmental Assessment of Trunk Control (SATCo), which seeks to estimate the degree of sitting trunk control in children with cerebral palsy (CP). Method: Thirty-one children with CP between 9 months and 16 years of age (22 males, mean age 8y...

Muscle mass in humans is inversely associated with circulating levels of inflammatory cytokines, but the interaction between ageing and training on muscle composition and the intra-muscular signalling behind inflammation and contractile protein synthesis and degradation is unknown. We studied 15 healthy life-long endurance runners, 12 age-matched u...

Background: It is unknown how and when the proximal attachment of the patellar tendon matures; puberty may be key in ensuring normal tendon formation. The aim of this study was to investigate the features of the proximal patellar tendon attachment at different stages of skeletal maturity, to help gain an understanding of how and when the tendon at...

Advanced Glycation Endproducts (AGEs) accumulate in long?lived tissue proteins like collagen in bone and tendon causing modification of the biomechanical properties. This has been hypothesized to raise the risk of orthopedic injury such as bone fractures and tendon ruptures. We evaluated the relationship between AGE content in the diet and accumula...

Background: Upper limb paresis is one of the most frequent and persistent impairments following stroke. Only 12-34% of stroke patients achieve full recovery of upper limb functioning, which seems to be required to habitually use the affected arm in daily tasks. Although the recovery of upper limb functioning is most pronounced during the first 4 w...

Background: Life-long regular endurance exercise yields positive effects on cardiovascular and metabolic function, disease and mortality rate. Glycation may be a major mechanism behind age-related diseases. However, it remains unknown if skin autofluorescence (SAF), which reflects glycation, is related to arterial and metabolic function in life-lo...

Statement of significance: Connective tissues hold all parts of the body together and are mostly constructed from thin threads of the protein collagen (called fibrils). Connective tissues provide mechanical strength and one of the most demanding tissues in this regard are tendons, which transmit the forces generated by muscles. The length of the c...

Increased tendon cell nuclei density (TCND) has been proposed to induce tendon mechanical adaptations. However, it is unknown whether TCND is increased in tendon tissue after mechanical loading and whether such an increase can be quantified in a reliable manner. The aim of this study was to develop a reliable method for quantification of TCND and t...

Background: Non-steroidal anti-inflammatory drugs (NSAID) are used as pain killers during periods of unloading caused by traumatic occurrences or diseases. However, it is unknown how the tendon protein turnover and mechanical properties responds to unloading and subsequent loading in elderly humans, and especially whether NSAIDs affect tendon adap...

The purpose of this study was to evaluate the role of TGF-β1 in regulating tendon extracellular matrix (ECM) after acute exercise. Wistar rats exercised (n=15) on a treadmill for four consecutive days (60 min/day) or maintained normal cage activity. After each exercise bout, the peritendinous space of each Achilles tendon was injected with a TGF-β1...

Purpose: Following Achilles tendon rupture, running is often allowed after 6 months. However, tendon healing is slow and the metabolic status of the tendon at this point is unknown. The purpose of this study was to investigate tendon metabolism (glucose uptake) and vascularization at 3, 6 and 12 months after Achilles tendon rupture as measured usi...

The musculoskeletal system and its collagen rich tissue is important for ensuring architecture of skeletal muscle, energy storage in tendon and ligaments, joint surface protection, and for ensuring the transfer of muscular forces into resulting limb movement. Structure of tendon is stable and the metabolic activity is low, but mechanical loading an...

In recent years a number of methodological developments have improved the opportunities to study human tendon. Microdialysis enables sampling of interstitial fluid in the peritendon tissue, while sampling of human tendon biopsies allows direct analysis of tendon tissue for gene- and protein expression as well as protein synthesis rate. Further the...

Purpose: To investigate between-leg differences in hip and thigh muscle strength and leg extensor power in patients with unilateral hip osteoarthritis. Further, to compare between-leg differences in knee extensor strength and leg extensor power between patients and healthy peers. Methods: Seventy-two patients (60-87 years) with radiographic and...

Background Lack of regular physical activity is a risk factor for functional decline. In hip osteoarthritis, exercise therapy aims to improve patients' overall function. Systematic reviews have shown beneficial effects on pain and physical function from exercise therapy (1) but also that these positive effects are not sustained in the long term (2)...

Purpose: To determine intra- and interobserver reliability and precision of sonographic (US) scanning in measuring thickness of the Achilles tendon, plantar fascia, and heel fat pad in patients with heel pain. Methods: Seventeen consecutive patients referred with heel pain were included. Two evaluators blinded to the diagnosis performed independ...

Here we review the literature on how tendons respond and adapt to ageing and exercise. With respect to aging, there are considerable changes early in life, but this seems to be maturation rather than aging per se. In vitro data indicate that aging is associated with a decreased potential for cell proliferation and a reduction in the number of stem/...

Background: Non-steroidal anti-inflammatory drugs (NSAIDs) may enhance resistance training induced gain in skeletal muscle mass and strength, but it is unknown if NSAIDs affects muscle loss during periods of inactivity in elderly individuals. Thus, we studied the influence of NSAID treatment on human skeletal muscle during immobilization and rehab...

This observer-blinded, randomized controlled trial compared the short- and long-term effects of 4 months of supervised strength training (ST) in a local fitness center, supervised Nordic Walking (NW) in a local park, and unsupervised home-based exercise (HBE, control) on functional performance in 60+-year-old persons (n = 152) with hip osteoarthrit...

The musculoskeletal system and its connective tissue include the intramuscular connective tissue, the myotendinous junction, the tendon, the joints with their cartilage and ligaments, and the bone; they all together play a crucial role in maintaining the architecture of the skeletal muscle, ensuring force transmission, storing energy, protecting jo...

Diabetic patients have an increased risk of foot ulcers, and glycation of collagen may increase tissue stiffness. We hypothesized that the level of glycemic control (glycation) may affect Achilles tendon stiffness, which can influence gait pattern. We therefore investigated the relationship between collagen glycation, Achilles tendon stiffness para...

Synopsis Tendinopathy is a very common disorder in both recreational and elite athletes. Many individuals have recurrent symptoms that lead to chronic conditions and termination of sports activity. Exercise has become a popular and somewhat efficacious treatment regime, and isolated eccentric exercise has been particularly promoted. In this clinica...

Among the connective tissues, tendons are probably some of the simplest in terms of structure and function. The function of tendon is basically that of a rope transmitting uniaxial force from muscles across joints to generate movement. Tendons can often experience large loads with many repetitions, which may be part of the reason why they are commo...

Diabetes is a major risk factor for tendinopathy and tendon abnormalities are common in diabetic patients. The purpose of this study was to evaluate the effect of streptozotocin-induced (STZ, 60 mg⋅kg(-1)) diabetes and insulin therapy on tendon mechanical and cellular properties. Sprague Dawley rats (n=40) were divided into four groups: non-diabeti...

The free Achilles tendon is considered a homogenous structure that transmits muscular force in a linear manner. However, the tendon undergoes longitudinal rotation and is separated in mechanically independent segments with distinct mechanical and material tissue properties. The present review examines the hypothesis that the human Achilles tendon i...

Previous studies have shown that eccentric training has a positive effect on Achilles tendinopathy, but few randomized controlled trials have compared it with other loading-based treatment regimens. To evaluate the effectiveness of eccentric training (ECC) and heavy slow resistance training (HSR) among patients with midportion Achilles tendinopathy...

Lysyl oxidases (LOXs) are a family of copper- dependent oxido-deaminases that can modify the side-chain of lysyl residues in collagen and elastin, thereby leading to the spontaneous formation of non-reducible aldehyde-derived inter-polypeptide chain cross-links. The consequences of LOX inhibition in producing lathyrism are well documented but the c...

We examined whether diastolic left ventricular function in young and senior life-long endurance-runners was significantly different from sedentary age-matched controls, and if life-long endurance running appears to modify the age related decline in diastolic left ventricular function. The study comprised 17 senior athletes (age: 59-75 years, runnin...

Matters of fiber size and myonuclear domain; does size matter more than age? The relationship between fiber size and myonuclear content is understood poorly. Biopsy cross-sections from young and old trained and untrained healthy individuals were analyzed for fiber area and myonuclei, and 2 fiber size-dependent cluster analyses were performed. Compa...

The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength was measured in 20 healthy people at four knee joint an...

tendon and skeletal muscle function adapts to physical training of resistive nature, but it is unknown to what extent persons with genetically altered connective tissue - who have a higher than normal tendon extensibility - will obtain any effect upon their tendon and muscle when undergoing muscle strength training. We investigated patients with cl...

In the past twenty years, the use of ultrasound-based methods has become a standard approach to measure tendon mechanical properties in vivo. Yet, the multitude of methodological approaches adopted by various research groups probably contributes to the large variability of reported values. The technique of obtaining and relating tendon deformation...

(1) Objective Isolated human tendon cells form 3D tendon constructs that demonstrate collagen fibrillogenesis and feature structural similarities to tendon when cultured under tensile load. The exact role of circulating growth factors for collagen formation in tendon is sparsely examined. We investigated the influence of insulin-like growth factor...

There is a clinical overlap between classic Ehlers-Danlos syndrome (cEDS) and benign joint hypermobility syndrome (BJHS), with hypermobility as the main symptom. The purpose of this study was to investigate the role of type V collagen mutations and tendon pathology in these 2 syndromes. In patients (cEDS, n=7; BJHS, n=8) and controls (Ctrl, n=8), w...

Tendon pathology is related to metabolic disease and mechanical overloading, but the effect of metabolic disease on tendon mechanics is unknown. This study investigated the effect of diet and apolipoprotein E deficiency (ApoE(-/-)) on the mechanical properties and advanced glycation end products (AGEs) cross-linking of non-weight bearing mouse tail...

Objective: To investigate the reliability and agreement of measures of lower extremity muscle strength, power and functional performance in patients with hip osteoarthritis at different time intervals, and to compare these with the same measures in healthy peers. Design: Intra-rater test-retest separated by 1, 2, or 2.5 weeks in patients, and 1...

Life-long regular endurance exercise is known to counteract the deterioration of cardiovascular and metabolic function and overall mortality. Yet it remains unknown if life-long regular endurance exercise can influence the connective tissue accumulation of advanced glycation endproducts (AGEs) that is associated with aging and lifestyle-related dis...

Background Hip osteoarthritis (OA) is a leading cause of pain and functional limitations (1). Current international guidelines recommend exercise as part of the core management for people with Hip OA but the effects of exercise in people with Hip OA are sparsely investigated (2, 3). Objectives In an observer-blinded, randomized trial to compare the...

High-load eccentric exercises have been a key component in the conservative management of chronic Achilles tendinopathy. This study investigated the effects of a 12-week progressive, home-based eccentric rehabilitation program on ankle plantarflexors' glucose uptake (GU) and myoelectric activity, and Achilles tendon GU. A longitudinal study design...

Objective: Persistent weakness is a common problem after anterior cruciate ligament- (ACL-) reconstruction. This study investigated the effects of high-intensity (HRT) versus low-intensity (LRT) resistance training on leg extensor power and recovery of knee function after ACL-reconstruction. Methods: 31 males and 19 females were randomized to HR...

Achilles tendinopathy is a highly prevalent sports injury. Animal studies show a growth response in tendons in response to loading in the immature phase but not after puberty maturation. The aim of this investigation was to examine the structural and material properties in long distance runners who were either physically active (HAY) or inactive (L...

It is unknown whether loss in musculo-tendinous tissue during inactivity can be counteracted by growth hormone(GH), and whether GH accelerate rehabilitation in aging individuals. Elderly men (65-75 years; n=12) had one leg immobilized two weeks followed by six weeks re-training, and were randomly assigned to daily injections of recombinant GH(rhGH,...

To investigate the influence of lifelong endurance running on the satellite cell pool of type I and type II fibres in healthy human skeletal muscle. Muscle biopsies were collected from 15 healthy old trained men (O-Tr) who had been running 43±16 (mean±SD) kilometres a week for 28±9 years. 12 age-matched untrained men (O-Un) and a group of young tra...

Magnetic resonance imaging (MRI) has commonly been applied to determine tendon cross-sectional area (CSA) and length either to measure structural changes or to normalize mechanical measurements to stress and strain. The ability to reproduce CSA measurements on MRI images has been reported, but the accuracy in relation to actual tendon dimensions ha...

Introduction: Osteoarthritis (OA) is the most common form of arthritis and the most common chronic joint disease in individuals over the age of 65 years. The condition is often associated with significant pain, stiffness, fatigue, and has a strong impact on physical function, mobility and quality of life. Objectives: The aim of the present study wa...

Tendons are important load-bearing structures, which are frequently injured in both sports and work. Type I collagen fibrils are the primary components of tendons and carry most of the mechanical loads experienced by the tissue, however, knowledge of how load is transmitted between and within fibrils is limited. The presence of covalent enzymatic c...

Tendons connect muscle to bone and transmit enormous, repetitive forces during movement. The prevalence of tendon overuse‐injuries is high, and these conditions are often prolonged due to inadequate tissue regeneration. Whether this relates to a slow tissue turnover is unknown since current methods provide diverging estimates of tendon protein half...

This study explored the age‐related deterioration in stretch‐shortening cycle ( SSC ) muscle power and concurrent force–velocity properties in women and men across the adult life span. A total of 315 participants (women: n = 188; men: n = 127) aged 18–81 years performed maximal countermovement jumps on an instrumented force plate. Maximal SSC leg e...

Introduction: Gender differences exist with regards to ligament and tendon injuries. Lower collagen synthesis has been observed in exercising females vs. males, and in users of oral contraceptives (OC) vs non-users, but it is unknown if OC will influence tendon biomechanics of females undergoing regular training. Material and Method: 30 female athl...

Tendons are often injured and heal poorly. Whether this is caused by a slow tissue turnover is unknown, since existing data provide diverging estimates of tendon protein half-life that range from 2 mo to 200 yr. With the purpose of determining life-long turnover of human tendon tissue, we used the (14)C bomb-pulse method. This method takes advantag...

# INFERRING TENDON MECHANICAL PROPERTIES USING ULTRASOUND IMAGING {#article-title-2} to the editor: Ultrasound imaging has provided an invaluable tool for investigating muscle and tendon mechanics, particularly for measuring tissue strain. However, as Finni and colleagues ([1][1]) argue, some

Background: Collagen-rich tendons and ligaments are important for joint stability and force transmission, but the capacity to form new tendon is poorly understood. In the present study, we investigated mechanical strength, fibril size, and structure during development of tendon-like tissue from adult human tenocytes (termed tendon constructs) in v...

Background: The Achilles tendon is one of the strongest tendons in the human body, and yet it frequently ruptures, which is a substantial clinical problem. However, the cause of ruptures remains elusive. Hypothesis: Ruptured human Achilles tendon displays inferior biomechanical properties and altered collagen composition compared with noninjured...

The aim of this study was to examine the structural and mechanical properties of the patellar tendon in elite male badminton players with and without patellar tendinopathy. Seven players with unilateral patellar tendinopathy (PT group) on the lead extremity (used for forward lunge) and nine players with no current or previous patellar tendinopathy...

Overuse Achilles tendinopathy is a common and challenging problem in sports medicine. Little is known about the etiology of this disorder, and the development of a good animal model for overuse tendinopathy is essential for advancing insight into the disease mechanisms. Our aim was to test a previously proposed rat model for Achilles tendon overuse...